Yard and Garden: May 29, 2015

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This is the Q&A for the Yard and Garden show for May 29, 2015. 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, 2015. 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 Fech, Extension Educator in Douglas & Sarpy Counties

1. A caller had fine webbing on her tomatoes, what is it and how can it be controlled? She also wondered about using blossom set on her tomatoes?

A: The fine webbing on the tomatoes would be spidermites. These can be controlled with a strong spray of water on the plants to knock the mites off and kill them. As for the blossom set, is not recommended as it does not have strong research to back the effectiveness of it.

2. A lady had a river birch and a dogwood shrub that are not leafing out at the top. Why is this?

A: The plants are going through environmental stress. This spring has been warm followed by very cold to warmer again and now just cool, cloudy, rainy weather. That follows 3 years of stressful environmental conditions starting with the drought in 2015. Many of our plants are experiencing a degree of winterkill due to these events, where the top of the plant is not leafing out but the bottom of the plant is. Many of our plants will eventually fully leaf out or just have some dead branches through them. With the dogwood, those dead branches can be pruned back, but wait 2 more weeks to see if any more of the plant comes back. With the river birch, it is not advised to top a tree, so the pruning practices will be more difficult and it would be best to consult an arborist for that.

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3. A caller has an Austrian Pine where the new growth is browning and lighter green, whereas the rest of the tree is dark colored. What is wrong with it?

A: The needles at this point are not fully elongated due to the late spring events. Give the tree time to fully come out of the winter dormancy period to determine the color differences. If at that point there is still a problem, email me or your local extension office for more information.

4. This caller has a Japanese Lilac tree that has brown branches with no leaves on them. What should be done with those branches?

A: Scrape the branches with a fingernail or pocket knife to see if there is any green tissue under the bark in the cambium layer. If underneath is brown it is a dead branch. Either way, wait until around June 15 to see if the branches will come back from winter dormancy. If not, then the dead branches can be removed at that point. Don’t remove any live tissue from the tree at that time of the year.

5. A caller wanted to know if you can get multiple cuttings from a broccoli plant?

A: Broccoli is a tough plant to grow in Nebraska because in typical years it gets too hot too soon in the summer to provide an efficient harvest. It is suggested to grow broccoli as a fall crop. This year, however, is a good year for broccoli in the spring due to the slow warm up we have seen. As long as you only cut out the broccoli florets, you can leave the leaves and provide additional side buds that can be harvested for broccoli meals.

6. This caller has a large silver maple in their yard and now they are finding multiple small seedlings of maples all around their landscape. How can those seedlings be controlled?

A: Mowing them off is the best practice or pruning them out while they are small and easier to control. Do not spray them with any chemicals for control because they could be suckers coming up off of the roots of the main plant and any chemical applied to root suckers can kill the entire tree. These seedlings could also be from the seeds that fall from the trees in samaras that resemble helicopters, but determining the difference is very difficult and it is just easier to only cut the seedlings rather than treat them with a chemical and risk harming the main tree that is enjoyed in your yard.

7. This caller has cherry trees that have suckers coming out from the base of the plant. What can be done to control those?

A: These suckers will have to pruned off repeatedly with pruners not the lawnmower. They are attached to the main plant and any chemical attempts would harm and possibly kill the main cherry tree. Typically, trees will begin to sucker when they are stressed. Ensure that the tree is well taken care of and healthy by providing it with a mulch ring 2-3 inches deep and as wide as they can make it. Water the tree at a slow trickle for 30-60 minutes one time a week during the hot part of the summer and only once every two weeks during the spring and fall.

8. This woman was wondering if now was the time to prune her snowball bush that is just finishing up the blooming period? She also wanted to know if this was the time to apply weed and feed to her lawn?

A: Now would be a great time to prune that spring blooming shrub. The rule of thumb is to prune spring blooming shrubs after they finish blooming for the year and prune summer blooming shrubs late in the winter before growth begins for the year. Now is the time to fertilize your lawn, but avoid using weed and feed products. The problem with a weed and feed product is that the weed control part of that needs to stay on the leaves and the feed portion needs to stay off of the leaves. It is a better practice to fertilize the entire lawn with only a fertilizer and spot spray with 2,4-D products only on the weeds in the lawn.

9. This caller’s daughter lives in Lincoln where flooding was a problem and she has a drainage ditch that has caused water to sit and is now concerned with mosquitoes. What can be done?

A: If the water is stagnant and there is no way to remove the water, it is best to use larvicides that are found in mosquito dunks that can be purchased at many box stores and garden centers. These mosquito dunks are not harmful to other wildlife or people.

10. This lady has a tree that has deer rubs on it. She placed a tree wrap tube on the tree and was curious about removal of the tree wrap.

A: The tree wraps and tubes are a great way to keep deer from damaging young, thin barked trees. They should only be left on for the winter months and then removed during the spring and summer. If left on they can girdle the tree if it gets too tight on the trunk and it can be a location for insects and diseases to get into the tree.

tree wrapping

11. This caller has Ponderosa Pines that have brown needles that cover 80-90% of the tree. It is only a problem on 2 of the many Ponderosa Pines that are all planted together. They have been planted for about 5 years and have shown this browning over the entire tree for 2-3 years. What can be done for this problem?

A: This could be a root issue dealing with stem girdling roots or a watering issue. It is hard to determine, but might possibly be due to low watering. Water the plants slowly for 30-60 minutes weekly in the summer and once every two weeks during the spring and fall. These trees may not make it through, if it is a root issue digging them up after they have completely died would help solve the problem.

12. The final caller this week wanted to know how late in the season they should harvest their asparagus plants?

A: They do need a period through the summer to rest from being harvested so they can build sugars to help them get growing next spring. It is best to quit harvesting when the stalks develop ferns, when they get small and spindly, and/or when they get woody. This will give the plant plenty of time to recover from this years harvest and prepare for next years harvest.

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Weather Effects on our Plants

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This year has been a bit unsteady regarding growing conditions for many plants. I have been getting a lot of questions regarding the death in many plants this spring and the lack of growth in many of our plants as well. I wanted to take this time to go over this issue with all of you.

This spring we have been seeing quite a bit of dieback on many different perennial plants and shrubs. Roses and spireas are suffering from what we call winterkill. Winterkill occurs commonly in the winter months when plants are exposed to cold, drying winds. The winterkill was extremely hard on these plants this year and has caused the tops of them to die. What we are seeing in our landscapes is plants that only have leaves at the bottom of the plant with no leaves and brittle branches at the top of the plant. Many other shrubs are experiencing the same problem. These dead branches can be pruned out of the plant. If the plant affected was a rose, it could have more problems if the dieback occurred below the graft union that many roses posses. If it died below the graft union, it should be replaced with a new rose.

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We are also seeing a great deal of loss in willow trees. Many willow trees, throughout the state, are dying entirely or losing the top or many branches throughout the tree. This is attributed to many years of tough growing conditions. In 2012 our plants faced severe drought and three weeks of temperatures in the 100’s. This is very hard on our plants and it takes 3-5 years of normal growing conditions for a plant to recover from a drought like this. This drought was followed by the winter of 2013-2014, which was very dry, cold, and windy. That winter caused many of our plants, especially arborvitae, to die due to the desiccation they faced. Finally, we have had a very uneven warm up this spring that followed a quick drop in temperatures last November, when temperatures fell to only 5 degrees Fahrenheit.

It is very hard on plants to go through so drastic extremes during their growing season and to have it hit them for multiple years at a time. This is the reason for so much death and dieback in so many different plants.

A lot of our plants are also very slow to warm up this spring. Butterfly bush, privet, hibiscus, and beauty bush have still not broken dormancy this spring. We at Nebraska Extension are suggesting waiting until the beginning of June before giving up entirely on these plants.

Many of our vegetable plants, if they have already been planted, may not be growing very well at this point. They are slow to grow well in this cool, cloudy weather. They will catch up when it warms up.

Keep an eye on all of your plants for diseases that are sure to be a problem with this weather. Leaf diseases and fruit diseases could be a problem this year as many are common in wet, cloudy weather. Watch leaves for leaf spots to remove those leaves as soon as you begin seeing a spot on them. When you need to water, be sure to water your plants from the bottom rather than overhead to reduce spreading these diseases.

Yard and Garden: May 22, 2015

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This is the Q&A for the Yard and Garden show for May 15, 2015. 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, 2015. 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: Kevin Korus, Diagnostician for the UNL Plant & Pest Diagnostic Lab

1. A caller with a river birch that is 5-6 years old was planted with 3 trunks and now it has 5 trunks. Should those be removed or will it harm the tree?

A: River birch trees are commonly grown as a multi-trunked tree. If additional trunks appear, they can be left on or cut off with no problems for the tree, as long as they don’t grow too large before they are removed. If the trunks to be removed have grown to be 1/3 of the tree or more or the trunks are 1/2 the size or larger than the main trunk, you would not want to remove these as that would be removing too much of the tree in one growing season and can cause more problems to the tree than benefits. If they are not in the way, I would suggest leaving all 5 trunks.

2. A gentleman wanted to know how and when to prune blackberries and raspberries. He has raspberries that have died from the top downward on some branches with green growth at the base of the plant. What should he do about this?

A: The top dieback would likely be due to water stress or winterkill which occurs during the winter months when we see little moisture. As for general pruning, there is a great guide from the University of Missouri Extension to describe the many practices of pruning brambles, Pruning Raspberries, Blackberries, Gooseberries, Currants, and Elderberries.

3. This caller has amaryllis bulbs that were growing great and now the leaves are starting to turn yellow. What is the cause of this and how can she stop it from happening?

A: This plant is likely in need of a fertilizer treatment. They should receive regular fertilization with a houseplant fertilizer. Also make sure that the plant isn’t sitting in water. Amaryllis plants should be watered when the top two inches of soil are dry to the touch.

4. This caller has Weigela ‘Wine and Roses’ that she had trimmed last fall. Now one of them is only greening up at the bottom of the plant, why is this?

A: This plant is suffering from winterkill. As long as the bottom is greening up, the plant should be fine. Those dead branches can be removed back to green growth or back to the ground if there is no green on the branch at all. Remember to keep plants watered on the warm days when we face a dry winter like we did last year.

5. This caller was curious about rhubarb. How long in the year do you harvest rhubarb in the year or can you continue to harvest all year long? When should they be transplanted? What do you do when seed stalks appear on the plant?

A: You can harvest the plant until the plant begins to produce slender stalks. After that the plant needs to be left alone to replenish the sugars and nutrients to continue growing and produce next year. The stalks can be cut off or they can be pulled off. When the seed stalks appear on the plants, they should be removed. The production of seed stalks takes energy from the plant to make the seeds rather than leaving it to produce leaves and the stalks. Transplanting rhubarb is best done in the spring of the year. Avoid harvesting for the first growing season after transplanting and only do light harvest in the second season. By the third season, harvest can resume as normal. This is to allow the plant to get a good root system developed before loosing much of its leaf area.

6. This caller has a pin oak tree that is 45 years old. He added a mulch ring to the tree recently and wanted to know if rock mulch or wood chip mulch is better for the tree?

A: Any mulch is better than no mulch. Wood chip mulches keep the roots cooler and hold in more moisture than the rock mulches, but the rock mulches will not blow away or need to be replenished each year like the wood chip mulches. Either way keep the mulch only 2-3 inches deep.

7. This caller wanted to know how far apart to plant her asparagus? She planted hers 1.5 feet apart, is this too far apart?

A: Asparagus should be about 6-8 inches deep and 12-18 inches apart. There isn’t a problem with planting it too far apart, the problem would occur if they are planted too close together. Plants not spaced correctly can lead to disease problems.

Flood Damaged Plants

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We have seen a lot of rain in the past couple of weeks. And, in many locations, we have seen a great deal of flooding. Long-term flooding can cause a great deal of damage to our landscapes and gardens, but thankfully we saw short-term flooding that many of our plants will be able to survive.

Lawns are very resilient in flooded areas. Many of our lawns are still quite wet from flooded conditions. It is best to stay off of wet lawns to avoid compacting the soil. Wait until it has dried out before mowing, driving equipment over, walking excessively over, and cleaning up the debris that may be on the lawn. Turfgrass can survive 4-6 days submerged, according to Missouri Extension. Most of our floods receded prior to 4 days, so the lawn should survive. We may see an increase in lawn diseases this summer due to the high amounts of rain and floodwater that affected them this spring.

Floods also could have damaged trees. Many trees that are planted near rivers and streams can withstand longer periods of flooding. However, when the floods move into our towns, it can cause problems to our other tree species. According to the University of Wisconsin Extension, most plants can tolerate a few days of flooding during the growing season. Certain tree and shrub species are going to be less tolerant of floods, but for the short time our floods lasted, our plants should be fine.

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Once the flooding recedes, make sure the roots don’t have more or less soil on them than before the floods. If more than 3 inches of soil or debris was added to the ground surrounding the tree, remove the excess to allow the plant roots to breathe. If water pushed soil off of tree roots, add soil back to those areas to ensure they are not more exposed than they were before the flooding.

Vegetable Gardens would be more of a concern for food safety reasons. The short period of time that they were underwater, should not affect their growth. Floodwaters are typically not very clean and they can carry bacteria and other debris with them as they move across the land. It is best not to eat any vegetable raw that was at any time under floodwaters. So the best recommendation for lettuce and spinach would be to discard the entire plant. Vegetables that were submerged by floodwater should be cooked to make them safe for consumption. The vegetables that may have been planted but are still too young to produce yet would be safe for consumption when they mature. The University of Wisconsin also suggests to increase safety of the vegetables that haven’t been under floodwater, cook them, or at least wash them well and peel them, if possible, before eating. Be careful to not allow any vegetables to fall onto the ground where they can come into contact with bacteria that could still be on the soil. A layer of mulch will help reduce this issue.

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Our plants should all survive fine from the few days of flooding that many of us saw. The only way to know for sure what damage occurred to our plants is to wait and see. These plants were put under a great deal of stress and therefore may be vulnerable to many disease and insect problems through this summer. Take extra care of them and watch for signs of problems to treat them early in the infestation.

Yard and Garden: May 8, 2015

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This is the Q&A for the Yard and Garden show for May 8, 2015. 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, 2015. 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: Graham Herbst, Community Forester with the Nebraska Forest Service

1. This caller has pampas grass growing in her yard that last winter had problems with winterkill. What would be a good alternative ornamental grass she could plant?

A: Pampas grass had a lot of problems with winterkill last spring due to the dry, cold, windy winter conditions we faced in the winter of 2013-2014. Pampas grass is on the edge of its hardiness zone in Nebraska, but there are many other options for native grasses here. Maidenhair grass, or Miscanthus, is a great choice for a large native grass and it has many varieties to choose many different qualities. Big Bluestem and Little bluestem are great native choices, as well as switchgrass, sideoats grama, and many more. Ornamental grasses give us winter interest and habitat and food for wildlife during the winter months.

2. A caller had a sewer that was dug out and filled with soil. She then seeded new turfgrass on the area that has come up and is growing well. This spring the area sunk back down 6 inches. What can she do to level this area out?

A: You can remove the grass from that area, gathering 4-6 inches of soil and roots with it. Add soil to bring that back up to level with the surrounding lawn, and replace the grass piece back on top. Keep this grass well-watered until it becomes established, it will act like a piece of sod. The other option would be to back fill the location with soil and reseed the area with turf seed.

3. A caller has orange odd-looking structures hanging off of her cedar trees. What is this? Will it harm the tree?

Winter gall of Cedar-apple rust.

Winter gall of Cedar-apple rust.

A: These would be the galls from a disease called cedar-apple rust. This disease requires 2 hosts to complete its lifecycle, a cedar and an apple or something else in the Malus family such as a pear or crabapple. This disease overwinters on cedar trees as a hard, brown, odd-shaped structure on the branches and with spring rains they open up to look like orange, gelatinous, galls that are reminiscent of an orange octopus. This is when the spores are spreading to the apple trees. This disease causes no real damage to cedar trees, but on apple trees it causes lesions on the apples and leaf spots. Here is a NebGuide on Cedar-Apple Rust.

4. This caller has 3 apple trees and this winter one of them has not bloomed nor leafed out. Is the tree dead?

A: Check the tree for living tissue by scraping the bark off to expose green or brown tissue underneath. If it is green, it is still alive, if it is brown it is dead. Also check the branches for flexibility, if they bend they are still alive if the break they are dead. Give the tree a few more weeks to see if it comes out of it later this spring.

5. This caller has moles in their yard. How can they be controlled?

A: Moles can be controlled with traps. These traps will euthanize the mole in the hole to be left behind after control has been achieved. These have the best effect if the mound is pushed down 2-3 times prior to placing the trap in the hole, this will show if the tunnel is an active one before the trap is placed in it. Here is a guide from the Internet Center for Wildlife Damage Management on Mole Control.

6. This caller has voles in their yard. How can they be controlled?

A: Voles are controlled with snap traps that we typically use for mice. Place 2 traps in the run from the voles, or the area where the grass is damaged. Place the traps perpendicular to the runs and place them facing in different directions in the run. So, for a vole run that goes North to South, place one trap facing east and one facing west. Here is a guide from the Internet Center for Wildlife Damage Management on Vole Control.

7. This gentleman had used Scotts liquid turf builder on his lawn and it is not working to green up the lawn or to reduce the weeds found in his lawn. He also has a zoysiagrass lawn that is not growing as well in some portions of his lawn as it has in the past. What would be causing these problems and how can he improve these?

A: Broadleaf weeds are best controlled in the fall so it is best to apply a broadleaf weed killer, such as 2,4-D, 2 times in the fall, such as September 30 and October 15. Even in the spring, some control can be achieved, but they will require more than one application as they are tough weeds to kill. The zoysiagrass may have experienced some winterkill so it might be wise to take plugs from the area of the lawn where it is growing well and move them into areas of the lawn where it is not growing so well.

8. This caller has ash trees that are getting oval-shaped holes in them and ants on the trunk of the tree. Did the ants do this to the tree? How can it be managed?

A: These ants are probably carpenter ants. Carpenter ants do not harm your trees, they will just burrow into wood that has already begun to decay for some other reason. Carpenter ants on a tree do not require treatment. The holes are most likely due to native borers of the ash tree, such as red-headed ash tree borers or ash-lilac borer. These borers can be controlled with a trunk spray with chemicals such as sevin or eight or apply a soil drench with an imidacloprid product around the base of the trunk. This doesn’t sound like it is Emerald Ash Borer because the holes from EAB are D-shaped, not rounded or oval.

9. This caller has an ash tree and wants to know when he should treat it? He has heard that it takes up to 5 years for the systemic insecticides to move throughout the tree into the canopy, if this is true should he treat now.

A: Systemic insecticides take only a couple of weeks to move throughout the entire tree and they only last for 1 or 2 years depending on which chemical is used. It is best to wait until Emerald Ash Borer gets within 15 miles of the tree before treatment begins because treatments are costly, damaging to the tree, and not necessary until the borer gets closer. Trunk injections wound the tree and after repeated years of treatments it causes a great deal of stress to the tree, so there is no need to treat and harm the tree prior to when it is necessary.