Yard & Garden: July 24, 2020

This is the Q&A for the Yard and Garden show for July 24, 2020. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and it will run through July 31, 2020. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.

Guest Host: Bob Henrickson, Horticulture Program Coordinator for the Nebraska Statewide Arboretum

1. The first question of the show was regarding peppers that are in a garden next to a soybean field. The peppers are wilted now and the caller was wondering if this was from herbicide drift?

A. Herbicide injury doesn’t typically look like wilted plants, that will cause cupped leaves or leaves that are deformed. If the plant is wilting, it could be from root issues. Make sure that the soil is dry before watering again. It could be from too much water.

2. The second caller is also struggling with his pepper plants. They seem to be quite wilted as well. The wilting seems worse during the heat of the day. Could it be something else?

A. With more information, it seems that both pepper plants seem to be having troubles with heat stress, which is common this year, across the listening area. There really isn’t much to do to fix heat stress, water won’t necessarily help with heat stress. Give them time and they will pull through and be fine. Keep them watered, but don’t overwater.

3. A caller has a linden with skeletonized leaves. What is the problem?

A. Japanese beetles are likely causing the problem. You can use sevin or other insecticides. They will likely not kill the tree, but will make it look bad. Most of the damage for this year could be done already. Look at the tree for more green beetles with copper-colored wings or elytra. If you don’t see many beetles, forego the spraying for this year.

4. This caller has bagworms on her cedars in the pasture. Will those move to her windbreak trees this year?

A. They should be in their location for the year now. They typically only move around when they are very small, at this point in the year they shouldn’t move much.

5. When is a good time to cut peonies back?

A. The fall is the best time to cut peonies and clean the plants up. They will turn brown in late September to early October, that is when they should be pruned back. This allows the plants to build sugars all summer to help with early spring bloom next year.

6. The final question of the show was from a caller that has a weedy tree in her yard that looks like a palm tree. What could that be?

A. Without seeing the tree it is hard to tell for sure what it is. It could possibly be a tree of heaven or a pokeweed plant. It was advised that she send a picture to the Extension Office.

*Reference to commercial products or trade names does not imply endorsement by Nebraska Extension or bias against those not mentioned.

Yard & Garden: July 17, 2020

This is the Q&A for the Yard and Garden show for July 17, 2020. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and it will run through July 31, 2020. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.

Guest Host: Sarah Browning, Lancaster County Extension Educator

2015-07-17 10.51.40
Green June Beetles

1. The first question of the show was from a listener who brought green beetles into the studio for identification. These were found in his trees and he wants to know what they are and how they should be controlled?

A. The beetles were Green June Bugs. These are a native insect species that can be found on many different plants. They can be ravenous feeders in grapes and occasional feeders in vegetable gardens, but on trees they are not very damaging. If they feed on vegetable gardens or grapes, you can use sevin or eight on them.

2. This caller has a Linden tree that is 12 years old that is losing leaves now. The leaves turn brown as well. They did recently give it a deep watering, but that isn’t seeming to help. What is wrong with the tree?

A. Check the tree thoroughly for Japanese Beetles, it is one of their favorite plants to feed on. They will feed heavily causing the leaves to look like lace and then the leaves will turn brown. The trees can look fully brown by late summer. If it is, you would want to work with an arborist to spray the tree. Be very careful with what you spray lindens with and when you spray them to not harm pollinators. If the leaves don’t have holes in them, it could be from a stem girdling root which cannot really be fixed so late in life.

3. A caller has peppers that have white spots on them. What caused this?

A. This is likely due to drift from Roundup or another glyphosate product. Wind can drift the particles which will leave white, irregularly shaped spots randomly across the leaves. If it was from a disease it would be more tan or brown in color.

4. This caller has tomato plants that are loaded with green tomatoes that are not turning red. What is disrupting the maturation process of the vegetables?

A. When the temperatures are so hot, as they have been, the fruit ripening process is slowed down or stopped completely. They will mature when the temperatures break to cooler temperatures.

5. A caller wants to know when she can harvest wild flower seeds to reseed in a new area in  her landscape?

A. The seed needs to fully mature while still on the parent plant. Make sure the seed head is dried and brown, then you can cut off the stalk and move the seed to the new location. If you can easily shred the seed  head with your fingers, the seed is mature and can be reseeded in a new location.

6. This caller has tomatoes and beans with troubles in the garden. The tomatoes have brown leaves on the bottom of the plant, what is causing that? The beans have flowers on them but no fruit has been set, why are they not producing beans for harvest?

A. The tomatoes likely have early blight, it is a common fungal disease that we are seeing this year. You can just remove the infected leaves and discard them to reduce the disease. If the plants still have troubles, you can spray them with a copper fungicide if necessary.

As for the beans, the heat is likely delaying fruit set. In temperatures this hot, the flowers can develop but the pollen can be killed so fruit will not set. Give the plants a little more time and they will start producing beans once the temperatures cool off.

7. A caller has columbines that are in a garden bed overrun by weeds. She wants to redo the bed to help get rid of the weeds. When is the best time to dig them up and do some work then replant them?

A. The fall or spring would be a good time to dig up, divide, move, and redo the garden space. When the temperatures are cooler. When we move or divide plants we break their root system, making it harder for the plants to get the needed moisture to survive. It is best to do these things when it is cooler so the drought stress isn’t as high.

8. This caller has tiger lillies that were knocked over by the wind and broken. Can the seed be moved to another location?

A. Make sure that the seed matures on the plant. If the stems were broken so the plant is not still maintaining the seed, they may not be able to be reseeded to a new location because the seed wouldn’t be mature. If that is the case,  you can divide the plants and plant some in the new location. September would be a good time to do this.

9. Is there any post-emergence herbicide that can be used in an asparagus patch that won’t hurt the asparagus?

A. No, there isn’t anything for post-emergence. You can use preen that is labeled for use in the asparagus in the spring prior to germination of the annual weed seed and again in the middle of the summer. This will help with annual weeds. For perennial weeds you can use roundup or another glyphosate product early in the spring prior to emergence of the asparagus. You can also use it after the final harvest of the year. Cut out all of the stems of asparagus and pull mulch or the soil up over the stems so no green is showing, then spray the roundup over the bed to kill the weeds and not harm the asparagus.

10. This caller has an old lilac that has leaves that look bad. Can it be cut down now?

A. It can be cut back with a rejuvenation cutting in September. This is when the lilac is cut back to 6-8 inches above ground. This will help to rejuvenate the plant to newer, healthier growth. This method will disrupt the flowering for a year or two, but it will eventually flower again. The lilac can also be caned out every year by removing 1/3 of the largest, least productive canes every year to remove those canes that are not improving the health of the plant.

11. A caller asked why his tomatoes look good but have no fruits or flowers at this point? It was hit by herbicide drift a month ago, but they have grown out of that.

A. The heat is pushing back maturation of the fruits right now. However, if your plants have no fruits at all, the herbicide injury could have stunted the plants. The combination is pushing back maturation of the fruits. Eventually they will flower and produce fruits, just give it time.

12. The last caller of the day asked about green beans that are blooming but have no fruits. What is causing this?

A. The heat is likely delaying fruit set. In temperatures this hot, the flowers can develop but the pollen can be killed so fruit will not set. Give the plants a little more time and they will start producing beans once the temperatures cool off.

*Reference to commercial products or trade names does not imply endorsement by Nebraska Extension or bias against those not mentioned.

Yard & Garden: July 10, 2020

This is the Q&A for the Yard and Garden show for July 10, 2020. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and it will run through July 31, 2020. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.

Guest Host: Justin Evertson, Green Infrastructure Coordinator for the Nebraska Forest Service

1. The first question of the show was from a caller who has a 20 foot tall blue spruce that the top 5-6 feet is turning brown. What caused this and what can be done about it?

A. This is likely from a canker. Canker fungi are common in blue spruce trees and will often cause the top portion of the tree to die. The dead area should be cut out but then you will lose the apical dominance and the tree won’t grow upward much after removing the terminal bud. It will die back to a certain spot then stop, the rest of the tree will remain healthy.

2. This caller has tomatoes with leaves that are curling. What is causing this?

A. Unfortunately, we aren’t completely sure what is causing this damage, but it is widespread throughout the whole state this year. It could be from herbicide damage due to chemicals still being used later in the year with the cooler spring and sudden change of temperatures to very hot. There is also thought that it could be from the beet curly top virus. This could also be from watering issues such as over watering or underwatering. It would be best to just pull the plants out because if it is the virus it can spread to the other plants and if it is herbicide injury the produce would not be safe to consume. If the other plants look ok, this would be the best option.

3. A walk-in listener has an row of arborvitae that have developed brown spots in them this summer. What is causing this?

A. Arborvitae struggle with the extreme temperatures that Nebraska have. The damage looks mostly like environmental stress. Keep them sufficiently watered, but don’t overwater. Keep them mulched in. Depending on the amount of dieback, they may survive.

4. This caller planted broccoli in mid to late May, now the leaves are developing holes and there is no head developing yet. What is wrong with it?

A. It is likely that the broccoli was planted too late and may not develop the head. Broccoli is more of a cool season plant, they don’t grow well in this heat. The holes are likely due to one of the looper caterpillars that are common on broccoli. Sevin will help with that.

5. A caller has a large pine tree that is looking dead, quite suddenly. It is losing a lot of needles and has turned brown. What is wrong with it?

A. This is likely due to pine wilt disease. There is no cure for the disease and no way to prevent it prior to infection. The tree should be removed.

She also wondered if she could still spray for bagworms?

A. We are quickly nearing the end of the time frame for spraying for bagworms. They are best sprayed when the bags are 1/2 inch in length or less. As the bags get too big, the sprays become less effective. Spraying soon should be ok, but if you wait too long you may not see 100% coverage from the sprays. Use Tempo and spray in the next week for best control.

6. This caller has an apple tree that didn’t bloom this year and the leaves look bad. Will it survive and is there anything to do for the tree?

A. The frost likely injured the blooms. They will not produce apples this year if that is what happened. The plants will still survive. After discussion, it seems that the apple trees have rust on them, which is common. The spray time has passed. You can spray the trees next spring with a copper fungicide for the rust or use an orchard fruit tree spray through the season next year to work on insects and diseases in the trees.

7. A caller has a forsythia and a red twig dogwood that have grown too large for the area. When can they be pruned so they aren’t blocking windows?

A. If flowers are not critical, these plants can be pruned most anytime. Pruning right now would reduce the flowers for next year, since they are mostly set on for next year already. However, the best time for pruning the forsythia is just after it has finished blooming and the dogwood would be in the late winter. They can both be rejuvenated by pruning all the way back to the ground, about 6-8 inches above ground. The rejuvenation pruning should be done in the fall.

8. This caller has tomatoes and cucumbers with spots on the leaves. Is this a fungus and should a fungicide be used?

A. This could be from a fungus, it is hard to tell without seeing the plants. However, it is not the same fungus, these would have different types of fungi. Fungi are typically host specific. If there are just a few leaves that are damaged, those could be removed and destroyed. If the plant seems to have a lot of damaged leaves, a fungicide could be used if desired. Watering from below on the plants or earlier in the day if using overhead irrigation can help reduce the spread and incidence of the disease. If using a fungicide, be sure to read and follow the label and follow the PHI or pre-harvest interval. The PHI is how many days to wait for harvest after an application of a pesticide is made.

9. A caller has 3 river birches and a corkscrew weeping willow. After the late frost this spring, there are branches that are now dead, with no leaves. Will these plants survive?

A. It is unlikely that they will survive if they are not green now. It is likely that the late frost injured them and they cannot recover. If it is a few select branches, you might be able to remove them and the tree may be ok, but if the majority of the canopy has no green leaves on it, they will not survive. These plants can struggle with the extreme temperatures of Nebraska.

japanese beetle JAK582
Japanese Beetle, Photo from Jim Kalisch, UNL Entomologist Emeritus

10. What can be done about Japanese Beetles?

A. The plants that the Japanese beetles are found on can be sprayed with carbaryl, bifenthrin, or chlorantraniliprole. For organic options neem or pyola can be used. Don’t use the traps, they will bring in more beetles than what you already have. Grub controls can help a little with the population size. Be sure to avoid spraying the flowers of any plants.

11. This caller has a wild plum thicket along their driveway. It is spreading too much into the driveway. When can it be pruned back to avoid scratching cars that drive by?

A. The areas of the plum thicket that are creeping out of normal growth can be cut back most anytime. They are a tough plant and should be fine.

She also has a vegetable garden that is not growing well this year. It is the same location that she has gardened for years, but the plants just are not doing well. Can she add manure to it and if so, when?

A. You can add manure to the garden. For food safety guidelines, fresh manure should be applied 120 days prior to harvest of any crops, so we advise adding manure in the fall. However, since this has been a good garden space, I would suggest doing a soil test prior to soil amendments to know exactly what the problem is and know how to fix it.

12. A caller has a silver maple that lost limbs and has started to split from the recent storms. Can the tree be pulled back together with a cable?

A. It is best to work with an arborist on this, to ensure it is done correctly. However, the tree may be too large for a cable to effectively help with the split. It may be time to remove this tree. Silver maples are prone to decay from wounds such as this, it is likely the beginning of the end for the tree anyway.

13. The final question of the day is about a black hills spruce that is browning sporadically on the ends of branches throughout the tree. What is wrong with it?

A. This tree could have freeze damage on the tips of the branches from the late frost and snow this spring. It could also be from a disease called sirococcus or needle cast. It would be too late for treatment with either of these diseases, but they shouldn’t kill the tree. The brown areas can be pruned out and next spring, it might be good to spray the tree with a fungicide.

*Reference to commercial products or trade names does not imply endorsement by Nebraska Extension or bias against those not mentioned.

Yard & Garden: June 26, 2020

This is the Q&A for the Yard and Garden show for June 26, 2020. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and it will run through July 31, 2020. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.

Guest Host: Kyle Broderick, Plant Pathology Extension Educator

1. The first question of the show was from a caller who missed the answer last week on the show regarding controlling grass in her red raspberries.

A. Mulch will be the best option for this area. Red raspberries grow upright so they don’t shade out the weeds as much as black raspberries. Glyphosate or Roundup can be used carefully around the plants as well. Use some type of a barrier between the grass and raspberries if sprayed or use a sponging type of applicator or paint it on the grass.

2. A caller has a mandevilla with leaves that are turning yellow with black edges. She also has a gardenia that is getting yellow leaves with black edges. What is this and can she fix it?

A. These plants are growing in containers being watered often enough. Be sure to check the drainage when watering to ensure the drainage holes are not clogged. Water containers until water runs out of the drainage holes. If that isn’t happening there may be a clog which could lead to root rot because the plants would be sitting in water. Be sure to test the soil before watering to ensure it is dry. Stick your finger into the soil to see if the soil is dry, if it is still wet, do not water until it has dried.

3. This caller has a new lawn, she thinks it is fescue. It was planted last year and last fall it looked great. However, when the hot, dry weather began this year, a few patches in the lawn dried up and look dead now. The lawn was described as drying up almost overnight as soon as the heat started and there was a black coloration to the plants. What is wrong with the lawn?

A. This could be drought injury, grubs, or pythium blight. The new plants likely don’t have a full root system yet which would cause it to dry up faster in the heat. Watering 1-1.5 inches per week would help with drought or heat stress. If she pulls up the turf and there are no roots, it would be from grub damage. Grubs can be treated now with a lawn grub control such as Merit or Grubex. If she takes a handful of the blades and puts them into a baggie and leaves them overnight, she might notice a fishy odor that would indicate pythium blight. Pythium will go away on its own, it doesn’t harm the crown of the plant and it will regrow.

4. A caller planted new grass a year ago after a new home was built. It was growing good, but now there are some grass plants that turn brown and have stickers on them. Would that weed have been in the turf seed? How can it be managed?

A. These are likely sandburs growing. They were not in the grass seed, they were most likely from the soil. When a new home is built, the area that was undisturbed before has now been worked up. Sandburs live in rocky, bare soil areas where grass doesn’t grow. They would have already been there when the home was built. Sandburs are an annual grassy weed, similar to crabgrass. They can be controlled with crabgrass controls. In the spring use a crabgrass preemergence herbicide and now that the sandburs have already germinated for the year, Drive or another product containing quinclorac can be used.

5. This caller has a tree row at his house. There are old firs or pines that seem to be dying out and now he has planted a row of blue spruce. The blue spruces are turning brown, starting on the inside of the plant moving outward. The damage on these spruces is on the side facing the old trees. What is wrong with these trees and what can be done to help them?

A. The old trees could be nearing the end of their life and may just be dying of old age. This does happen. As for the blue spruces, it could be a needle cast disease which is common on spruce trees and is prevalent now. It is not effective to spray with fungicides now, but next spring they can be treated with chlorothalonil. They should be sprayed when the new needles are half expanded and then again 4 weeks later when the needles are fully expanded. There could also be some problems on the spruce trees from the location near the dying firs or pines. They are likely not getting the airflow they need and the needles are staying wet longer. This could be intensifying the needle cast disease.

6. A caller wants to know what our opinion is on transplanting trees now? He would be moving them with a tree spade.

A. Regardless of the size of the tree or how it is moved, it would be difficult to keep a tree alive in this heat. If planting from a container grown tree, there would not be much for a root system on the new tree so it would have difficulty getting water as often as needed. If it is brought in with a tree spade, many of the large roots will be cut and it would still be hard for the tree to get the moisture it needs. It is best to plant trees in the spring or fall, when it is cooler and rains more often to keep the tree well watered through the establishment period. They are best planted prior to Memorial Day and then again after Labor Day. We advise against planting in the summer months.

*Reference to commercial products or trade names does not imply endorsement by Nebraska Extension or bias against those not mentioned.

Yard & Garden: June 19, 2020

This is the Q&A for the Yard and Garden show for June 19, 2020. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and it will run through July 31, 2020. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.

Guest Host: John Porter, Extension Educator, Douglas & Sarpy Counties

1. The first question of the show was from a walk-in listener. He had a dwarf Aberta spruce tree that was shooting out long stems of larger growth that didn’t look like the original plant. What is wrong with it?

A. This is reversion. Dwarf Alberta spruce commonly reverts back to the blue spruce parents. The dwarf Alberta spruce actually came from cuttings and grafted trees from a mutation in the original spruce tree. It is unusual growth in the main plant that the plant breeders have taken to make a new tree that is new and interesting. However, even after years of maintaining those traits, another genetic mutation can occur sending it back to the original parent growth of larger and faster growing. Those reverting parts, or large, wild growing branches should be pruned back or eventually the tree will look mostly like the general blue spruce or white spruce.

2. A caller has red raspberries that have been established for 7-8 years. Now the patch has a lot of grass growing in among the raspberries. How can the grass be controlled?

A. Mulch will be the best option for this area. Red raspberries grow upright so they don’t shade out the weeds as much as black raspberries. Glyphosate or Roundup can be used carefully around the plants as well. Use some type of a barrier between the grass and raspberries if sprayed or use a sponging type of applicator or paint it on the grass.

She also wondered what to do with the old canes of the raspberry plants. Should they be cut out?

A. Yes, remove them. Raspberries have perennial roots but the canes are biennial. The first year of growth for a cane is to grow the leaves, the second year is when that cane produces berries, then after that the cane dies out. Canes should be removed during the dormant season after they have fruited.

She also has peony plants and would like to know when is best to prune those back?

A. Peonies should be left to grow throughout the year and cut back in the fall after they turn brown. They need the leaves to grow throughout the summer months to build sugars for the roots so they can bloom well next year. The flower stalks can be removed, but the leaves should be left to grow until fall.

3. A caller has blackberries growing in a garden space in the middle of his native grass prairie area. There are now canes coming up and spreading throughout the prairie. How can those be controlled?

A. Blackberries will send out runners from the main plant. These runners are still connected by underground roots, rhizomes, so spraying a chemical on them could kill the main plant as well. It is best to just dig out the plants in the grass. You could use glyphosate or Roundup on the runners, but you would need to cut the runner first to cut the tie to the main plant.

4. This caller has spruce trees that have the tips of the branches dying and those tips are hooked over like a shepherd’s crook. They also have one that the top has died. What is wrong with these trees?

A. The tips of the branches look like the damage from a disease called sirococcus. To control Sirococcus shoot blight, apply a fungicide such as chlorothalonil (Daconil, Bravo) when new shoots are ½ to two inches long, typically in May; and repeat every 3 to 4 weeks if frequent rains occur. For more information, visit this Nebraska Forest Service publication on Diseases of Evergreen Trees. You would be a little late to spray now for this year, but could treat it next spring.

As for the top dieback, that is likely canker, a common disease in spruces. You will have to cut 6-8 inches below the dead area to get rid of that. This will remove the apical dominance in your tree and cause it to grow wider rather than upright. You can train a new leader by keeping one shoot growing more upright and taller than the others.

5. Is there a certain pH that is recommended for vegetable gardens?

A. The general recommendation is to have a pH close to neutral which is 7.0 The best growth from a vegetable garden is when the pH is 5.8-6.5 Below 5.5 or above 7.5 generally requires soil modification. To get the pH you can get a soil sample kit from your local Extension Office and send it in with a sample from your garden. For more information on how to do a soil sample, visit this NebGuide For more information on fertility requirements for your garden, visit this NebGuide

She also wondered about cedar apple rust and what to use to treat the cedar trees from this?

A. It is not necessary to treat cedar trees for cedar-apple rust because the galls on the trees do not harm the tree. If you have susceptible apple trees nearby, those should be sprayed when the orange galls are seen on the trees.

6. When is the best time to transplant roses?

A. Late fall is the best time to move roses, after they have gone dormant. They can be difficult to move, so be sure to take as much of the rootball as you can get.

How can you kill scrub trees growing around the roses?

A. Cut the trees off and paint the stump with glyphosate, or Roundup. You could also use the ‘Glove of Death’ method. This is when you wear a chemical-resistant glove and then put a cloth glove over that. Then, dip a few fingers of the gloved hand into Glyphosate and rub those fingers along the stem and leaves of the trees to kill them.

7. How can you manage grass in the vegetable garden?

A. Mulch would be the best option. No pesticides are labeled for use in the home garden without a Restricted Use pesticide license.

8. This caller has pampas grass that has grown large and now has a dead center. What can he do to get rid of the dead center?

A. The best option would be to dig up he pampas grass and divide it and then replant the new sections. This will eliminate the dead center. The fall would be the best time to do this.

9. A caller has a maple tree that was planted 3 years ago. Last year and again this year it has leafed out but the top third of the tree will lose all the leaves early in the summer and never regrow those leaves. What is wrong with it?

A. Unfortunately, it is likely that this tree is dying and will not recover. This is most likely caused by a root issue. A large root may have been injured when it was transplanted to this location or it could have a root rot issue. After discussions, she was watering the tree all night once a week. This is too much water for the tree. A newly planted tree would have a small rootball and would only need to be watered for about 20-30 minutes once a week, even a full grown tree would only need to be watered for about an hour at the slow trickle method. This tree was likely sitting in water for a few days after this long watering which would have caused the roots to rot and this will cause dieback from the top of the tree first followed by full tree death. It would be best to remove this tree and start over.

10. This caller has a pin oak tree with branches that hang over the sidewalk. When can she prune it and where should she prune the branches?

A. Oaks are prevalent to a disease caused oak wilt that is caused by a beetle spreading the disease when it feeds on a tree. The beetles are attracted to wounded trees, pruning the tree causes a wound. Because of this, oaks should not be pruned in the summer months. They are best pruned in the later fall. Prune back to the trunk, just outside of the branch collar. If you don’t want to cut all the way back, you can cut back to a side branch that is at least 1/2 the size of the branch that is being removed. Do not just cut to a random location in the middle of the branch.

11. A caller has thistles in her pasture. She went out to cut them the other day and noticed something had been feeding on the thistles. What was that?

A. There are some insects used to manage thistles, the thistle tortoise beetle is one. It is likely that this was feeding on the thistles which will help to control the population of the thistles.

12. This caller has 12 tomatoes, 2 of them have curling leaves at the top of the plant. What is causing this?

A. Unfortunately, we aren’t completely sure what is causing this damage, but it is widespread throughout the whole state this year. It could be from herbicide damage due to chemicals still being used later in the year with the cooler spring and sudden change of temperatures to very hot. There is also thought that it could be from the beet curly top virus. This could also be from watering issues such as over watering or underwatering. It would be best to just pull the plants out because if it is the virus it can spread to the other plants and if it is herbicide injury the produce would not be safe to consume. If the other plants look ok, this would be the best option. This condition is one that is being constantly discussed in Nebraska Extension this year.

13. The final caller of the show has an American Elm tree that 1/2 of it has leafed out and the other half has died. What is wrong with it?

A. It is likely that this plant has Dutch Elm Disease, just like the elm we discussed on the show last week. There is no control or prevention for this disease. American elms were mostly wiped out in the 1960’s due to this disease but a few have survived or came up naturally. The American elms that are still alive will eventually die due to the disease, it will get to them. He can send a sample into the UNL Plant Pest Diagnostic lab for confirmation, but if it is Dutch Elm disease, the tree should be removed.

*Reference to commercial products or trade names does not imply endorsement by Nebraska Extension or bias against those not mentioned.

Yard & Garden: June 12, 2020

This is the Q&A for the Yard and Garden show for June 12, 2020. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and it will run through July 31, 2020. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.

Guest Host: No guest host due to COVID-19 and social distancing

1. The first caller of the show has tomatoes that only grew to about 1 foot tall and then they died back from the top. What is wrong with them?

A. It could be that they need to be watered more effectively. He has the plants mulched with grass and is watering, but just using a hose-end sprayer. When just watering with a hose like that the top couple inches of soil get wet then it spreads out rather than down, so the plants aren’t getting enough water to their roots. It could also be from a disease, but it is hard to tell from just a description.

2. A caller has watermelon radish plants that are going to seed. Can she cut the flower stalks off so they continue to grow? The radishes are not very large yet.

A. These plants are not going to grow much longer. When we get to hot weather the cool season crops will go to seed or bolt and will not live long, radishes are one of those plants. She said she had to replant later in the year due to frost damage in late April/early May, that is just too late to plant radishes for a good crop. She could try again in the fall or plant earlier next spring.

3. A caller has an American elm tree that has a few branches that are dying off. He has cages of rabbits underneath the tree and wondered if too much nitrogen was being applied to the roots or if the roots are reaching up to under the chicken coop with high nitrogen?

A. It is more likely that this tree has developed Dutch Elm Disease and will likely die. There is no control or prevention for this disease. American elms were mostly wiped out in the 1960’s due to this disease but a few have survived or came up naturally. The American elms that are still alive will eventually die due to the disease, it will get to them. He can send a sample into the UNL Plant Pest Diagnostic lab for confirmation, but if it is Dutch Elm disease, the tree should be removed.

4. This caller is actually from Oklahoma, but was doing work in the area to call in. He was wondering what we do for squash bugs?

A. Squash bugs can be difficult to control in a garden and most of the time once they are in your garden, they will always be there. For chemical controls, sevin, eight, or bifenthrin are all labeled for use in the vegetable garden. Be sure to watch the PHI, pre-harvest interval, or amount of days to wait from application until harvest. For squash bugs make sure you are spraying thoroughly on the underside of the leaves where the eggs are laid to kill larvae just as they emerge. You can also squash the copper-colored, football shaped eggs as you find them on the underside of the leaves. Be sure to clean up the garden in the fall to eliminate the overwintering site.

5. This caller had 3 questions. First, when and how short can a spirea be pruned?

A. It is a spring blooming spirea, so it should be pruned within a few weeks after blooming has completed for the year. Up to 1/3 of the plant can be removed in one season. So if it is 3 feet tall, you can remove 1 foot of the growth. Be sure to prune back to a side branch. Continual shearing will leave heavy growth at the base of the plant with spindly growth on top. Spireas can be renewed with a rejuvenation pruning where it is cut back to 6-8 inches above the ground. This should be done in the fall and not every year. You will not see blooms the year following a rejuvenation pruning.

How do you prune lilacs? It is overgrown.

A. If the lilac is overgrown, it can be pruned through a rejuvenation pruning in the fall, like suggested with spireas. Otherwise, it should be pruned within a few weeks after blooming has been completed in the spring.

His final question was about tree black walnut. The tree was pruned at a random location mid-way through the branch. It has now died back further than where it was pruned. What is wrong with it?

A. Be sure to make a good pruning cut. Branches either need to be pruned back to the trunk, just outside of the branch collar, or to a side branch. The side branch needs to be at least 1/2 the size of the branch being removed.

6. A caller has poppies that she received from the Yukon. These poppies are blooming now and she wants to dead head so they continue to bloom, but she also wants to save the seed to start some new plants. Can she cut the flower heads off before they fully dry to save the seed?

A. The seed needs to be allowed to fully mature on the plant. So, unfortunately, you will have to choose between dead heading and allowing the seed to mature on the plant. If they are picked too soon, some may germinate, but the rate will be low.

7. An emailed question regarding the listeners garden which was hit by herbicide drift. Will the produce from this garden be safe to consume?

A. There is no way to know for sure when or if the produce will be safe to eat. It is better to throw it out and start over when in doubt.

8. This caller was curious about collecting seed from winter onions, or walking onions. She tried last year but they didn’t grow at her house after she took the above ground bulbs from her sisters plants. What does she need to do differently to get these onions to grow?

A. These also need to be allowed to fully mature on the plant, like the poppies. The stems with the above ground bulblets on them will dry up and fall over. When they are falling over the bulblets are mature and can be picked up and planted in new locations. If the bulblets were picked off the plant prior to this, they were not fully mature and wouldn’t develop into new plants.

9. A caller has oak trees that the branches are dying from the bottom up. What can be done?

A. These are likely pin oak trees and it is very common in pin oak trees. The lower branches could be dying due to lack of sunlight. It could also be due to a few diseases. If the branches are dead with no leaves, they should be removed to keep them from falling. If this continues, a sample could be submitted either by photo to me or a sample to the diagnostic lab at UNL, linked above.

10. This caller has tomato plants that were cut off at the ground level but the plant was left behind. What caused that? How can this be stopped?

A. This was likely due to cutworms. They can be managed by using sevin or diatomaceous earth around the base of the plant when they are planted. You can also wrap the base of the plant with aluminum foil to prevent feeding. This caller took the plants inside the next day and placed them in water and in soil to try to re-root them, it worked for some. Great idea, if caught early enough!

She also wondered if diatomaceous earth is effective for squash bugs?

A. It would not be as effective for squash bug adults. It can be used for squash bug nymphs.

Bagworm4
Bagworm

11. A caller sprayed his evergreen trees with Tempo to treat for bagworms and it rained just a few hours later. Will he need to respray?

A. The label states that it is rainfast after 24 hours, it is likely that this application was mostly washed off. The label also states that it can be reapplied every 7-10 days, so it would be best to wait about 7 days before reapplying. It would still be within the timeframe for spraying bagworms at that time.

12. This caller has been able to hand-pick bagworms off of her small tree through the year. Does she also need to spray?

A. If you are able to continue to pick the bagworms off as you see any new bags form, you wouldn’t have to. If you see a large amount of small, black caterpillars or if a large quantity of bags form on the tree, you can spray.

13. How often can you spray Eight to control squash bugs?

A. Remember to always read and follow the label when using pesticides. It would likely be fine to spray every 10-14 days through the season, but one label I looked at said every 3 days if necessary. Just be sure to follow what your label states and also follow the PHI, pre-harvest interval, or amount of days to wait from application until harvest.

14. A caller has an oak with old scars where limbs were removed by previous home owners. One of the wounds is weeping. What is causing this weeping? What can be done about it?

A. This is likely due to a bacterial infection of the heartwood, called wet wood disease. Those pruning scars did not fully seal over and it has allowed the bacteria to enter the tree. It is minimal damage to the tree and won’t kill the tree. There is nothing to do to stop the weeping, but again it doesn’t really hurt the tree.

15. The final question of the day was from a caller who has cucumber plants with leaves that are drying up and dying. What is causing the browning which starts on the outside edge of the leaves? Can anything be sprayed on the plants to stop the damage?

A. This is likely either environmental stress or a slight fungal disease. The environmental stress could be due to the heat or drought stress if they aren’t receiving sufficient irrigation through this hot, windy weather. It could also be from a fungus, there are many that affect cucumbers. A fungicide, such as copper, could be used to reduce the spread. Without a picture, it is hard to determine for sure what is affecting these plants.

*Reference to commercial products or trade names does not imply endorsement by Nebraska Extension or bias against those not mentioned.

Yard & Garden: June 5, 2020

This is the Q&A for the Yard and Garden show for June 5, 2020. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and it will run through July 31, 2020. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.

Guest Host: No guest host due to COVID-19 and social distancing

1. The first caller of the show would like to know when the proper time is to spray for bagworms?

A. After they have hatched, which is different every year, based on temperatures. It is typically around the middle of June. This week, the UNL Entomology department reported that bagworms have hatched in the Lincoln and Omaha area so if they haven’t hatched in Southeast Nebraska yet, they likely will in a week or so. We should be in the spray window for the next few weeks.

2. A caller has large trees in her yard that are shedding large amounts of leaves recently. What is causing this? Will the tree be ok?

A. This could be from a variety of factors. In some cases, the trees may have put on a large flush of leaves this spring. With the extreme heat and humidity recently, they dropped the extra leaves. They could also be leaves that have a minor leaf spot disease that has caused a large amount to drop off. Either way, the trees are still in good health with a full canopy of leaves and should be fine for future growth.

3. When can a large hosta be divided?

A. At this point for the year, it would be best to wait until next spring. It is now hot and windy so it would be very hard for the plant to tolerate being divided and replanted. Hostas are best divided in the spring before hot weather but after they have emerged well.

4. This caller has potato plants growing and now the edges of the leaves are curling up and turning brown. What is wrong with them?

A. The caller is watering his potatoes correctly, but does not use mulch. This could be one of two fungal diseases brown leaf spot or early leaf blight. Fungicides such as mancozeb or chlorothalonil can be used to control this, but the wet weather recently is likely the reason it is showing up. Mulching the plants will also help so that the spores don’t splash from the soil back up to the leaves of the plant. Be sure to clean up the garden at the end of the year and rotate the potatoes around to different areas of the garden each year.

2019-06-07 10.05.02
Herbicide injury on Tomato

5. A caller has tomatoes that the top leaves are tight and deformed. What is causing this and do they need to be replanted?

A. This is likely from herbicide drift, it is hard to say for sure without seeing the plants, but it sounds most like herbicide drift. This has started to become a problem again this year due to the change in weather. As we warm up, we see more problems with 2,4-D and dicamba products that turn to a gas and move to non-target plants. Tomatoes are very sensitive to drift from 2,4-D or Dicamba products. They should grow out of the damage, however because we don’t know exactly what product hit these tomatoes there is no way to know for sure when the product will be out of the tomatoes. I can’t say when or if these tomato plants will be safe for consumption this year.

6. This caller grew cucumber plants last year and the vines took over her small garden. Can she cut them back to keep them away from her other plants?

A. Yes, the vines can be cut to reduce the growth slightly. I wouldn’t cut too much off because that can reduce the yields. It might be better for her to use a bush cucumber in future years that will not spread as far. She can also try using a trellis to have the cucumbers grow up rather than out.

7. A caller has sapling trees growing up in her chain link fence. What can she do to kill them?

A. These should be cut off and treated with a stump treatment, painting a herbicide on the freshly cut stump. Roundup would be the best to use in this heat and around other plants. She asked about using a brush killer and this can be used, but shouldn’t be used too close to desired plants. Always read and follow the label when using pesticides

8. This caller was curious if bagworms would run their natural course and if he would be able to quit spraying his trees eventually?

A. Unfortunately, bagworms are here to stay. They will never fully go away. Bagworms, like all insects, go through peaks and valleys in their population and right now we are nearing the peak. This means we have very high populations that are doing damage to our plants. When the bagworm population drops, you may be able to discontinue spraying for a few years if the population isn’t large in your trees. For now, you will want to spray with the high populations.

9. What are the orange things on the cedars and what plants will they damage?

A. These are the galls of cedar-apple rust. This disease needs 2 hosts to complete its lifecycle. The galls are hard, gray/brown structures on the cedar trees over the winter. In the spring, when it rains, these galls open up to allow the spores to move to the apple trees. When the galls open up they are orange structures that resemble an octopus due to all the telial horns around the gall. The disease causes no problems to the cedar trees, but will cause lesions on the leaves and fruits of apple trees. If you have a susceptible apple tree, now is the time to spray with a fungicide to prevent the disease from affecting your tree. For more information, view this NebGuide.

10. Is there any reason to spray fruit trees this year since the blossoms all froze and no fruit will develop?

A. It wouldn’t be necessary, if you want to take a year off of spraying. The trees will still develop some damage on the leaves, but it shouldn’t kill the tree. For fruit trees in Nebraska, you can either spray throughout the entire summer to combat all the problems or you can not spray and have some problems. If there will be no fruit, it wouldn’t be necessary to spray the tree.

11. A caller has an old rose that bloomed but now the leaves look to be drying up. What is wrong with it?

A. It is hard to tell for sure without seeing the plant. There are a few different fungal diseases that could be affecting the roses now after all the rain we have seen recently. It may also be that the plants were shocked by the sudden onset of hot, humid, windy environmental conditions after the cool spring. They could also have damage from rose slugs, which are out right now. He also said they are surrounded by brome grass which could be causing competition issues. Most of these problems will fade on their own. If it is a fungal disease, there are rose specific fungicides that can be used. Rose slugs are minor problems and will go away as fast as they appeared, without chemicals.

12. The final question of the day was a caller who had planted a butterfly milkweed. overnight it was pulled out of the ground so he replanted it and it was again uprooted the next night. What is causing this? It is only on the new butterfly milkweed plant.

A. I assume this is damage from a squirrel or other type of wildlife. The best defense against wildlife damage would be to put a fence around the plants being damaged. There would be nothing else that would be very effective, or proven to work through research, in this case.

 

Yard & Garden: May 29, 2020

This is the Q&A for the Yard and Garden show for May 29, 2020. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and it will run through July 31, 2020. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.

Guest Host: No guest host due to COVID-19 and social distancing

1. The first caller of the show has tomato plants that now is developing “skinny” leaves. What is wrong with them?

A. The leaves are skinny and deformed. This is likely from herbicide drift, it is hard to say for sure without seeing the plants, but it sounds most like herbicide drift. This has started to become a problem again this year due to the change in weather. As we warm up, we see more problems with 2,4-D and dicamba products that turn to a gas and move to non-target plants. Tomatoes are very sensitive to drift from 2,4-D or Dicamba products. They should grow out of the damage, however because we don’t know exactly what product hit these tomatoes there is no way to know for sure when the product will be out of the tomatoes. I can’t say when or if these tomato plants will be safe for consumption this year.

2. This caller has a very large hosta. When can it be divided?

A. Early spring is the best time to divide hostas, once they have emerged from the ground but before the heat of the summer. It might be a little late to divide the plants this year due to the hot weather expected next week. If they are divided now, be sure to keep them well watered.

3. When can oaks and maples be pruned?

A. The new pruning recommendations show that pruning is best if done in late spring, so late May to early June for Nebraska. Now would be a good time for most trees, however, oaks are susceptible to oak wilt if pruned during the summer months. It is best to wait until fall, September or October, to prune oak trees to avoid this disease. Maples, can have a heavy sap flow in the spring, they can be pruned now, but may leak sap, sometimes large quantities. They would be better to prune in the fall also.

4. A caller was going to use Grass-B-Gon on some weeds she recently hand-pulled to reduce the hand-pulling in the future. How long should the regrowth be before she applies the grass killing product to her landscape beds?

A. As long as you start to see some new, green regrowth, the product should work. According to the label, it should be applied anytime weeds are actively growing, which would be when you see them green up again around your landscape plants.

5. This caller is on her second round of planting tomatoes and they are turning yellow again. She planted the first in late April and then again recently. In the new planting one plant is starting to turn yellow. She is using straw mulch on most of the plants but is using grass mulch on the one plant that is turning yellow. What is wrong with her plants?

A. The first round of plants were planted too soon and we saw quite a bit of cold weather later in the season this year than many other years. She did cover the plants on the sides, but left the top exposed. Frost would have settled down onto the plants and killed them. The new plants are doing fine except the one plant that has grass clippings on it. The lawn has been treated with broadleaf weed control as well as crabgrass control this year. The labels will tell you not to use the clippings on the garden for the season or for a period of time. If that isn’t being followed and this is the one plant that is looking bad, I would assume that the grass clippings are the problem. Be sure to use clean grass clippings or use straw for all of the plants.

6. A caller pulled 3 mature barberry bushes with a pickup truck and then decided to replant them after all. What should be done to keep them alive? Should they be fertilized?

A. Pulling these plants out with a pickup truck and chains would have drastically damaged the cambium layer which can reduce the flow of water and other nutrients through the plant. They were also kept out of the ground for a week before being replanted. These plants could pull through if they are tough, but you will need to make sure they are kept moderately watered. Don’t overwater, but don’t allow the plants to dry out either. A slow trickle for about 10 minutes a couple of times per week will help to rebuild the roots. Do not fertilize them. Fertilizing a stressed plant can further stress the plant. Only time will tell if they can survive.

7. This caller has lilacs that are looking bad and didn’t bloom well. What can be done to help them? When can they be pruned?

A. Sounds like this lilac is in need of a rejuvenation pruning. This is where you cut the plant off about 6-8 inches above the ground level to rejuvenate the growth. It will reduce insect problems and push new, young growth to provide better blooming and have a healthier plant. This can be done in the fall for best results.

8. A caller had bagworms on her cedars last year. She also noticed a lot of praying mantis egg cases, she knows they are a good predator.  Are the praying mantis’ helping to control the bagworms?

A. Praying mantis’ are not a major predator of bagworms. They prefer feeding on aphids and others.

She also wondered about her forsythia that was injured by the late frost this year. It didn’t bloom this year and she had to cut back some of the branches. Will it bloom next year now or did this damage the blooms for next year as well?

A. The blossoms are set on the new growth that will form this summer. As long as they are pruned back within about 3 weeks after their bloom period, they will still bloom next year. This is why we prune forsythia just after they bloom rather than in the late winter. This forsythia should still bloom next year.

She had one final question, how can she control a clover-type weed growing profusely in her iris beds?

A. This will be difficult to do without harming the iris plants. She could spray with Roundup using a piece of cardboard as a barrier between the weeds and the iris plants or she could use the “glove of death”. This is when you wear a chemical-resistant glove and then put a cloth glove over that. Then, dip a few fingers of the gloved hand into Glyphosate and rub those fingers along the stem and leaves of the bindweed to kill it.

9. What can be done to control elm saplings in a windbreak?

A. You can go through and cut off the trees and follow that up with a stump treatment using either 2,4-D or a glyphosate product, such as Roundup. The Roundup would be better this late into the year to avoid volatilization issues from the 2,4-D in the heat. Use the concentrate and just paint it on to the freshly cut stump for best control. Do NOT use Tordon, that will likely kill the spruce trees, and it is against label directions.

10. A caller planted grass in the spring. It is getting to about 2 inches tall now. When can he spray the weeds coming in with the grass?

A. You should wait until after 3 times mowing the new lawn before any herbicides should be applied to the grass to avoid injury. However, by that time, it will be too hot to use any 2,4-D products, which will turn into a gas and move to non-target plants and injure them in temperatures above 80-85 degrees. It would be better to just wait it out and spray in the fall to manage the weeds after the turf is more established. The fall is a better time to treat for perennial broadleaf weeds because it is when the plant is taking nutrients back into the root system and it will take more of the herbicide with it. Spray twice in the fall, once in mid-September and again in early to mid-October.

11. This caller has a hydrangea that didn’t look like it was going to live through the late frosts this spring. She did notice that it is finally coming up but it is only about 3 inches tall and is setting blossoms on. Should she remove those or let the plant bloom at such a small size?

A. It would be best to remove those blooms to allow the plant to grow a bit more before trying to bloom. All the energy in that plant would push into flower production, at such a small size, it would be best to allow the plant to build leaves and the root system to help it so it comes back next year.

12. A caller wants to know what to do to keep iris blooms from falling over?

A. Sometimes if the flower is too heavy it can fall over a bit. There are metal rings you can purchase to put in flower beds around plants that fall over to keep them upright, but nothing else will work for this. The flower is just too heavy for the stalk.

13. If branches on a tree or shrub are already dead can they be pruned off now?

A. Yes, dead branches should be removed as soon as they are noticed to prevent injury or damage from a falling branch.

14. The final call of the show asked if they should be fertilizing lilacs that were planted 3 years ago?

A. Fertlilizer doesn’t need to be used on plants that are growing just fine. Most trees and shrubs can get the nutrients they need to survive from our soils. The best thing is to do a soil test prior to adding any soil amendments, nutrients can build up to a too high level which can also damage the plant.

*Reference to commercial products or trade names does not imply endorsement by Nebraska Extension or bias against those not mentioned.

Yard & Garden: May 22, 2020

This is the Q&A for the Yard and Garden show for May 22, 2020. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and it will run through July 31, 2020. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.

Guest Host: No guest host due to COVID-19 and social distancing

1. The first caller of the show wants to know how much manure he should apply on his garden?

A. Manure should not be applied to a garden during the growing season. For food safety reasons, it should only be applied in the fall. The guidelines recommend waiting 120 days after adding manure before vegetables should be harvested from the garden if the edible portion of the plants come into contact with the soil. If fertilizer is necessary, general fertilizers for a garden would be sufficient. If unsure how much to add, a soil test should be done so that you don’t apply too much fertilizer.

2. This caller wants to know if castor beans are poisonous? She is mainly concerned for her dog who may eat the plant if she plants it.

A. Yes, the seeds of castor beans are poisonous. If she can ensure to pull the bean pods off throughout the season, it should be ok. However, it would be best to double check with her vet to be sure for the dog’s safety.

3. Is it too late to plant potatoes? How about sweet potatoes?

A. It is getting a bit late to plant potatoes for this year. Sweet potatoes are still fine to plant, though. They should be planted in mid-May to early June for best success.

4. A caller has an Empress clematis that is not blooming after 3 years of growth. Why is that?

A. This could be from cold weather damaging the blooms. If the blossoms were just about ready to open up as the snow came or cold temperatures, it could have injured them. It does take a few years for the flowering to reach its full potential, so that could be part of it as well. Finally, make sure that the clematis is not getting too much Nitrogen fertilizer overflow from a lawn. Too much nitrogen can make the plant very healthy but not produce flowers.

5. This caller is looking for a plant to place on the south and west sides of a brick house that only get 1-2 feet wide. What can be planted in this location?

A. This is a difficult location due to the heat, it is in full sun and will receive reflective heat from the brick house. Also, the size will be hard to fit into. She could look at some sedums, there are some smaller varieties and they like hot, dry locations. Salvia may be ok, but it would have to be pinched back through the summer to keep the plants smaller. Daylilies also could work, but may grow too large. Missouri primrose or penstemons could be a smaller choice that would grow well in this location.

6. A caller has cedars that have poison ivy and virginia creeper, also called woodbine, growing up through the trees. What can he do to control the vines?

A. You can’t spray the vines as they are growing on the cedars, it will harm or possibly kill the cedars. It is best to cut them off near the ground and then treat the stump with a brush killer. Do not use Tordon, it is not labeled for use there and it can spread to the roots of the cedars. If you cannot get to the poison ivy or are highly sensitive to the plants, you may want to call a lawn spray company to spray it for you to keep you from developing a rash.

7. This caller started tomatoes inside and they have now been transplanted into the garden but the bottom couple of leaves are turning yellow. What is causing this?

A. This is likely due to environmental conditions. It has been cool for tomatoes. As long as the top of the plant is maintaining healthy, green leaves, the plants should be fine. If the bottom leaves die back, they can be removed.

8. A caller has noticed that the bagworms are just emerging from their bags and it looks like they have started to chew on the needles of his trees. Should he wait a little longer to spray them or should he do it now?

A. Give them a little more time to ensure that all have hatched before spraying. If you spray too soon, you will miss those that are later to hatch. Watch for very small bags to begin to form on the tree, that is a good time to start spraying, before the bags are more than 1/2 inch in length.

9. This caller has a weeping willow tree that is 4 years old and still isn’t growing well, it is planted in full sun. What is wrong with it?

A. Be patient, it may take a little while to get over the transplant shock. Also, be more diligent when watering the tree. It should be watered once a week with a slow trickle for about 20-30 minutes. If the tree isn’t receiving this, it could be part of the problem.

10. Why are the peonies not blooming yet? They usually are blooming by now.

A. The cold weather is pushing back their bloom time. Also, the snow or freezing temperatures in late April to early May could have damaged the buds. Give them time to bloom a little later this year.

11. A caller has tomatoes that were damaged in the freeze this year. The leaves wilted and fell off but the stalk is still green. Will they come back or should they be replanted?

A. It would be best to replant. Those plants have no leaves to build sugars to grow, it is likely that they won’t live through this.

12. When should you stop harvesting asparagus?

A. When the spears start to get very spindly, it is best to stop harvesting your asparagus. Also, the spears will start developing the ferns quickly on those spindly spears, that is another indication to stop harvesting to allow the plants to grow for the rest of the season.

2014-04-23 10.45.50
Winterkill on Arborvitae

13. The last question of the show this week was from a man who is struggling to get American arborvitae to grow here. He planted some last year, some more this spring, and is watering every day but some are not greening up. What is the problem?

A. Watering could be an issue. Rather than just watering each tree a short period of time every day, it would be better to water slowly for longer periods of time, but less often. We need to encourage the roots of the trees to grow deep for best longevity. Water the trees once a week for 15-20 minutes each time would be better. Also, add mulch around the trees to help with competition and root growth. Some of these trees may have had issues with winter desiccation, which is common in arborvitae trees. Watering over the winter, once a month on warmer days, will help them get through. Evergreen trees still transpire through the winter, if transpiration is more than the water they take in through their roots, desiccation can occur. Anti-desiccant products can be sprayed on the trees through the winter to help as well.

*Reference to commercial products or trade names does not imply endorsement by Nebraska Extension or bias against those not mentioned.

Yard & Garden: May 15, 2020

This is the Q&A for the Yard and Garden show for May 15, 2020. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and it will run through July 31, 2020. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.

Guest Host: No guest host due to COVID-19 and social distancing

1. The first caller of the show wants to know how to plant the flowering plants he received from the Lower Big Blue NRD in Beatrice on the show last week? How far apart to space them and what type of growing environment should they be planted in?

A. Give the plants plenty of space, they are all large shrubs or small trees. The selection included Nanking cherry, redosier dogwood, lilac, crabapple, and caragana. They all need at least 8 feet of width and height. They all take full sun, but the redosier or red twig dogwood can take part shade. They could be planted on the interior of a windbreak to add to it or throughout a landscape.

2. A caller received a hydrangea plant as a gift for Mother’s Day. The flowers are now droopy. Should it be planted outside or what can be done to improve the flowers?

A. Yes, plant it outdoors. It can be planted in a container, but that would need to be protected over the winter months. Otherwise, plant it outdoors in part sun. The plant may also be finishing up the bloom period for this year, so remove those spent blossoms when they begin to turn brown.

3. This caller has iris borer. Should she dig up the plants now to remove the highly infected, mushy areas?

A. Leave them for now but clean out the mushy rhizomes as much as you can and spray the plants with an imidacloprid product to kill the larvae. Dig up the plants in the fall and clean them out. Next spring spray the plants earlier to prevent more damage. Also, be sure to clean off the dead leaves in the fall, this will destroy their overwintering location.

4. A caller has strawberries with a leaf spot disease. What can be done with them? He is already harvesting.

A. To prevent further spread and reduce diseases in the future, use soaker hoses to water rather than watering over the top of the plants. Also, make sure you have mulch around the plants which can also help reduce the spread of diseases. Captan can be used through the season for leaf spot disease. Spray every 10 days through the season, next year start before they begin to bloom. Be sure to follow the PHI listed on the product for strawberries. The PHI is the Pre-Harvest Interval, the amount of time to wait after applying a chemical before harvesting.

5. A caller has cedar-apple rust on his cedars that is harming them and causing the branches to turn orange. What can he do for it?

A. Cedar-apple rust is not damaging to cedar trees. If the branches are becoming covered in orange, it could be cedar-quince rust which can cause problems on cedar trees. You can spray the trees with Captan, Daconil, or Mancozeb to treat cedar-quince rust.

6. This caller has beans and popcorn that was planted from seed a while ago but it has not sprouted yet. Why is that?

A. It has been too cold for them yet. The soil temperatures are hovering just below 60 degrees and most of our warm season plants need at least 60 degree soil temperatures to grow well. Give them time, they should sprout in the next week or so as the weather warms up more.

7. A caller has Elephant Ear that was in the garage over the winter. She planted it in a lick tub before the last weekend with the cold temperatures. It has not yet sprouted, will it be ok or is it likely done?

A. It is still quite chilly for something like an elephant ear. Even though the plant had not yet emerged before the frost events last weekend, the lick tub may not have protected it enough since it is a bulb that needs to be dug up every year. Give it time, it might be ok though. It is hard to tell for sure yet.

8. This caller has wild violets in her yard. She had it treated twice in the fall and they are still coming up. What can be done about that?

A. Wild violets are very difficult to manage. They cannot be eliminated in a single treatment or even in multiple treatments in one year. It will take time and reapplications to really knock them back. 2 applications in the fall will be most effective. Apply a 2,4-D product in mid-September and again in mid-October for best control. Because we don’t know when the lawn was sprayed, or exactly what was spryed on it, it is hard to tell for sure why the plants are still so bad. Diligence with this plant would be best.

She also wanted to know how to control nutsedge in her lawn.

A. Nutsedge can be controlled with a sedge-specific chemical such as sedgehammer or sedge ender among others. Apply these chemicals before the longest day of the year, June 21st, to help reduce the population for next year. It isn’t a preemergence herbicide, but it will reduce the growth for future seasons.

Her final question was how to control weeds through the summer in an area that she has planned to overseed this fall?

A. Keep mowing the area will help reduce the flower and seed production through the year. She can continually spray roundup on the area throughout the summer to keep them down as well. Spray the Roundup 2 weeks ahead of overseeding to help kill it off before planting. She could use mesotrione, found in Tenacity, at seeding to help with weeds and not harm the seeding.

9. Why are the peonies not blooming yet?

A. With all of the cold weather we have had, it has slowed the growth of plants such as peonies. They are behind their normal blooming time for the year due to the snow and frost so late this spring. Give them time to flower a little later. They likely will not bloom by Memorial Day this year because of how cold it has been this spring. However, depending on the stage of development of the flowers when the snow and frost occurred, the blooms may have been damaged and may not open up this year. Give the plants time to recover into mid-June before giving up on the blossoms.

10. This caller is trying to grow rhubarb. It will start growing in the spring but then just stops growing larger and isn’t getting very large stalks. What is the problem?

A. It might be good to try a soil test to see how the soil nutrient levels and pH are where the plants are growing. You could try some fertilizer to help it grow larger. These plants were purchased from a flea market, from another grower, it might be that the plants were older and maybe not as productive. Try to start a new patch with new plants purchased from a nursery or garden center.

japanese beetle JAK582
Japanese Beetle, Image from Jim Kalisch, Retired from UNL Entomology

11. A caller has linden trees that had a problem with Japanese beetles last year. What can be done to control them this year?

A. After they have finished blooming, the trees can be sprayed with bifenthrin or chlorantraniliprole. Make sure you can get to the top of the tree for best control. He may need to call an arborist to spray the trees more thoroughly. Treating the yard for grubs can help. Don’t put a trap in your yard, this just brings more in from the surrounding locations.

12. This caller is wondering why her iris’ are not blooming? The plants of the same variety are blooming on one side of her house but not the other. Why is that?

A. The cooler weather is causing many of our plants to slow down or not bloom when they normally would be blooming. If the iris are blooming on one side of the house and not the other, and they are the same variety, this could be due to the microclimate on the sides of the house. One side may warm up sooner in the day causing those plants to warm up more and bloom sooner. Maybe the wind is hitting the one side more causing those plants to stay cooler longer. Give them time, they should all bloom eventually.

She also wondered why her celery is yellow. Is it due to the cold damage or is she overwatering?

A. It could be due to the cold weather. She is watering every other day for 2 hours per day with a sprinkler, this could be too much water. Monitor how much water is actually applied during that time by using a catch can. Vegetable gardens need about 1 inch of water per week. I would assume this celery is getting more than that.

13. Why are there so many seed stalks in the rhubarb plants this year?

A. The cold temperatures this spring are unusual and have “confused” the plants. This has pushed the plants to produce seed stalks. When rhubarb plants begin to produce seed stalks they push their energy into seed production and not into leaf and stalk production. To push that energy back into the stalk production we desire from rhubarb, cut the seed stalks off of the plant.

14. The final caller of the day has onions that are turning white and falling over. He didn’t cover them in the freezing weather last weekend. Is it cold weather injury that is causing this damage?

A. It is likely that this is from the cold temperatures. Even onions can be injured by temperatures in the low 30’s like what we saw. If there is green in the lower leaves, they might regrow.

*Reference to commercial products or trade names does not imply endorsement by Nebraska Extension or bias against those not mentioned.