Yard and Garden: June 10, 2016

Yard & Garden for blogThis is the Q&A for the Yard and Garden show for June 10, 2016. 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 August 5, 2016. 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: Paul Hay, Gage County Extension

1. The first caller of the day has a small Dwarf Alberta Spruce that is turning brown. What would cause this?

A. This would be from spider mites. This particular tree species is very susceptible to spider mites. They can be controlled with a strong spray of water or insecticidal soaps, horticultural oils, or a general insecticide such as a permethrin product.

2. This caller wanted to know if it was still ok to apply the second fertilizer application for the lawn?

A. Yes, you can do one around Memorial Day. I would suggest waiting until after this heat wave passes through and make sure the lawn is well-watered when you do fertilize, so you don’t fertilize to a drought-stressed plant which can cause leaf burn.

3. What would cause Clematis leaves to turn yellow, the plants still bloomed fine this year?

A. Clematis has a problem with Iron chlorosis. This could be iron chlorosis which can be treated with an iron fertilizer.

2015-09-22 18.45.39

Squash bugs on zucchini

4. A caller wanted to know what the best control for squash bugs in the garden would be?

A. Squash bugs will become active soon. Look on the underside of the leaves of your cucurbit plants such as cucumber, zucchini, squash, pumpkins, and melons. Squash bugs lay their eggs on the underside of the leaves. If you find the eggs, squash the eggs or remove the leaves. You can also spray for them. Spray on a rotation of every 10-14 days throughout the growing season. Switch between at least 2 of the following: sevin, eight, or bifenthrin.

5. This caller has rocks near the lawn and near some trees. There are weeds growing up through the rocks. Can glyphosate, or Roundup, be used around these trees?

A. If the trees are not close enough to be spraying directly on the trunk or leaves, then it will be fine. Glyphosate is not mobile through the soil like some chemicals.

6. This caller wanted to know what to do about the gnats outside? He cannot go outside right now without being attacked by gnats.

A. There is no longterm cure for gnats, much like mosquitoes. Using bug sprays, especially those containing DEET, will help the most. If you have an outdoor event coming up, you can treat the lawn and surrounding plants with sevin or other general insecticide, but these will not last for more than 2-3 days.

7. Is it too late to plant sweet potatoes? What can you do about grasshoppers in the landscape?

A. No, it is not too late to plant sweet potatoes. This is a warm season crop that really doesn’t like the early spring planting. They will do fine if planted in late May to early June. For grasshoppers in the landscape, they can be sprayed with any general insecticide. If in or nearby the vegetable garden use sevin, eight, or bifenthrin for safety of the produce. Be sure to spray the insecticides in the ditch, roadside, and fence rows where grasshoppers are found in high numbers.

8.  This caller has hemlock in the pasture. Is it poisonous? How can he control it so his cattle don’t eat it?

A. Yes, poison hemlock is poisonous if eaten, not if it is touched. Cattle can be poisoned by it, but they typically don’t eat the poison hemlock if there is an alternate food source. Use 2,4-D or Grazon in the pasture to control poison hemlock or dig it out.

*Don’t use 2,4-D this late in the season around landscape plants and never use Grazon or other products that contain Tordon in a landscape setting.

9. A caller has common mullein in his pasture. How can it be controlled?

A. Common mullein is best controlled with 2,4-D or Grazon. Make sure you spray down into the heart of the plant to get the chemical past the hairy leaves. It is best to spray the smaller plants, it would be too late to spray the larger plants that already have a flower stalk on them. Removal of the flower stalks will help reduce seed production from the full grown plants.

10. This caller has a 16 foot river birch that was planted last fall. Now the leaves have turned yellow and are beginning to fall off of the tree. Can it get too much water? What would cause this problem? She hasn’t been watering the tree much yet since it was planted in the fall.

A. Yes, plants can be overwatered to cause death. Newly planted trees need to be watered because they have no root system developed. A tree that was transplanted at this large of a size is going to have a great deal of transplant shock to overcome. Water was sitting in the hole when the tree was planted, so there may be an issue with water draining from the location. Use a probe or long screwdriver to see if the tree needs water. Push the probe into the soil 12-18 inches, if it goes in easy it doesn’t need water, if it is hard to push the probe in very far, the tree needs to be watered.

11. The final caller of the day wanted to install an electronic timer for watering his garden. What would be the best time to set his timer to water his garden?

A. 4 am-10 am is the best time to water any plants. This helps to water the plants while they are already wet from the dew period. It also helps to water early in the day so that the plants will dry out before night. Plants that are wet and cooler overnight introduce a great environment for diseases to occur. To reduce diseases, it is best to water early in the morning.

Advertisements

Yard and Garden: June 26, 2015

Yard and Garden Green Logo

This is the Q&A for the Yard and Garden show for June 26, 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: Sarah Browning from Nebraska Extension in Lancaster County

1. A caller has a pine tree with needles that are turning brown at the bottom of the tree. What would cause this?

A: There are a couple of common fungal diseases on pine trees, needle blight and tip blight. Both of these diseases will start from the base of the tree and move upward. Depending on the species of tree, it could also be pine wilt, but this disease progresses rapidly, causing death in only a few months. There are fungicides to be used for needle and tip blight, but they are best used in May and June. Neither of these fungal diseases should kill the tree in one growing season. This publication from the Nebraska Forest Service, Diseases of Evergreen Trees, shows pictures of both diseases and pine wilt and goes over treatment methods.

2. This caller has tomatoes that have black specks on the leaves which eventually turn yellow and die, but there are no specks on the tomatoes themselves. She was also curious why it makes a difference to water from below rather than above?

A: This would be a fungal disease called black speck or black spot. It is best controlled through good sanitation practices such as watering from below the plant, removing infected leaves as they are first seen on the plant, removing plants in the fall after the growing season, avoid crowding plants, rotating plants each year in the garden, etc. There is a great NebGuide on Leaf and Fruit Diseases of Tomatoes that will be helpful with many of our tomatoes this year with all of the rains as we are seeing many more leaf diseases. Watering from below the plant helps reduce spores splashing from plant to plant and from the soil to the plant. Watering from below also helps to keep the leaves dry throughout the day and into the night to reduce leaf wetness and humidity in the plant which is conducive to disease development.

3. A caller has a bur oak that is 15 feet tall with leaves that are curled under. What would cause that?

A: This could be herbicide damage from a 2,4-D product. It could also be from aphids or lacebugs. To determine if it is due to insect feeding, look on the underside of the leaves for tiny, green bugs, lace-like bugs, or frass. If it is aphids, they can be controlled with many general insecticides. Lacebugs rarely warrant insecticides as their damage is minimal to the tree. If it is herbicide drift, the tree should grow out of it, depending on severity of damage.

Bagworm

Bagworm

4. Is it time to spray for bagworms yet?

A: They have not yet begun to emerge in Southeast Nebraska. They are behind in their development this year due to the cool spring. They should be emerging in the next week or two. Ensure that the immature bagworms are active on your tree before treating to get best control from your pesticide.

5. Another caller wanted to know if it is illegal to use rainwater in Nebraska?

A: No, Nebraska does not have a law to prohibit the catching and use of rainwater, as some other states do. Rainwater is a good use of extra water to avoid so much runoff and contamination to the water supply. Be careful to not use rainwater on vegetable crops to avoid contamination from non-potable water.

6. This caller has a Kentucky coffeetree that was planted in the right-of-way by the city within the last 2 years. The bottom of the tree has leaves and new growth, but the top of the tree does not. Will it survive?

A: This tree probably is having troubles with establishment or may have been planted incorrectly. Due to this, the top of the tree is not receiving water and nutrients from the roots. It can be pruned back to the growth with possible success. Be sure to watch for a new leader to develop or you may have to start a new one to help it grow taller as the central leader will be pruned off of the tree.

Photo by Howard F. Schwartz, Colorado State University, Bugwood.org

Yellow Nutsedge Photo by Howard F. Schwartz, Colorado State University, Bugwood.org

7. How can nutsedge be controlled in lawns?

A: A product that is specific for use on sedges can be used in the lawn with no harm to the turfgrass. The most commonly used product for yellow nutsedge is Sedgehammer, it should be applied multiple times throughout the growing season, as new plants come up. It is better to spray with Sedgehammer early in the life of the new plant to reduce nutlet production and reduce the size of the plant.

8. A caller wondered when the best time is to prune an oak tree?

A: It is not advisable to prune oak trees during the summer months to avoid chances of getting oak wilt in the tree. The best time to prune oaks, and many of our deciduous trees, would be in the dormant season, such as November.

9. A caller has a fescue lawn that is getting yellow in spots. What would be the cause of that?

A: This year we have faced many days of cool, wet, cloudy weather which is favorable to many turfgrass diseases. This sounds like it is either brown patch or dollar spot disease. Brown patch has tan colored lesions on the leaf blades that have a dark margin around the tan spot. Dollar spot would just be tan spots in the lawn that are typically half-dollar sized but you can see many dollar spots coalesce into one larger spot. As the weather dries out and warms up, the fungus should fade in the lawn, or you can use fungicides in the lawn if necessary.

10. A caller has bindweed in the lawn. What can be done to control it?

A: A herbicide that is just for broadleaf weeds will work on the bindweed and not harm the lawn. Triclopyr is a great choice to use. This is commonly found in brush killer, poison ivy killer, and clover killer in the stores. Make sure that the temperature on the day of application is below 85 degrees Fahrenheit to reduce the risk of harm to non-target plants.

11. A lady has cucumbers that are flowering with no fruits developing. What would cause that?

A: Cucumbers have both male and female flowers on the same plant. Early in the season you may see development in only male flowers with no female flowers to produce no fruit. The female flowers will have a tiny cucumber structure at the base of the flower. This also could be due to low pollinator presence in the garden. Rainy days and hot days discourage pollinators. Give the plants more time, they should begin to produce female flowers and fruits soon. Hand-pollination may also be necessary if it is due to low pollinator presence. To hand-pollinate, take a Q-tip and touch the pollen of all of the flowers.

12. A caller has a clematis plant that is dying back, causing all of the leaves to turn brown.

A: Clematis commonly gets a fungal root and crown rot. If this plant was in a location where water sat this year with all of the heavy rains, it may have caused this fungal disease to occur. Cut the plant back to the ground and see if it will grow back, if not, you will need to replant.

13. This caller has Iris plants that have completed their blooming period for the year. Can these be cut back now?

A: No, all spring blooming plants need to be left, without being cut off, for the remainder of the summer until their foliage turns brown in the fall. This allows the plants to make sugar throughout the summer months to have a starting supply for early spring blooming next year. The flower stalks can be removed after the flowers are done.

14. A caller has patches of clover in the lawn. What can be done for management for the clover?

A: The best time for treatment of clover is in the fall with a Triclopyr or 2,4-D product. At this point, the temperatures are too high for herbicide control without possible harm to non-target plants. Both of these products can turn into a gas and move to non-target plants if temperatures are above 80-85 degrees Fahrenheit, the 2,4-D can volatilize for up to 72 hours. Be sure to mow the clover prior to herbicide treatment to mow off the flower blooms and cause less harm to bees.

15. A caller has grass planted in late March and added more seed later in the spring. She used a starter fertilizer and covered the areas with straw, and now there are brown spots appearing in the lawn. What would be causing that?

A: Brown patch disease is common on young seedlings of tall fescue. Look for irregular shaped tan spots with a dark margin to know if it is brown patch. Bayleton is a good fungicide that may still be effective on this lawn. Also, remove the excess straw to reduce disease problems.

16. That same caller has crabgrass coming up around her trees. Can she use roundup to control it?

A: Roundup can be used around the base of trees with minimal damage to the trees. A better option would be to use a post-emergent crabgrass herbicide such as Dimension or Fusilade.

17. A caller wanted to know if it was allowable to use Grass-B-Gone in their sweetcorn?

A: No. Grass-B-Gone kills all types of grasses, including sweetcorn. Also, Grass-B-Gone is not labeled for use in a vegetable garden.

18. A gentleman has mock orange and bridal wreath spirea. When can these plants be pruned?

A: Both of these plants have just finished blooming for the year so they can be pruned now. Remove no more than 1/4 of the plant in a growing season. This can be done by removing the largest canes at the base of the plant. If it is too tall, you can remove 1/4 of the height, if it is a 4 foot tall shrub you can prune it back to 3 feet tall.

19. A caller wanted to know what to do for management of dandelions in their lawn?

A: Dandelions are best controlled in the fall with a 2,4-D product.