Yard and Garden: June 21, 2019

Yard & Garden blog, 2019

This is the Q&A for the Yard and Garden show for June 21, 2019. 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 2, 2019. 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: Steve Karloff, District Forester for the Nebraska Forest Service

1. The first question of the show was about a Colorado Blue spruce tree that is turning brown throughout the whole tree. It seems to be starting at the ends of the branches. What is wrong with it?

A. This could be that it is simply too wet. The excess moisture this year is causing problems with a lot of our plants. Colorado Blue spruce trees grow best in the conditions in Colorado with a lot less humidity and moisture. Steve has seen quite a few spruces turning brown this year, most likely due to root rot issues from the high precipitation from this spring. Unfortunately, there is nothing that can be done to fix this problem.

2. Can you still prune forsythia shrubs this late into the year?

A. No, it would be better to wait. The general guidelines are to prune spring blooming shrubs within a couple of weeks after they have finished blooming for the year and to prune summer blooming shrubs in the late winter before they bud out for the year. At this point, pruning the forsythia will affect the blooms and it would be too hot to prune in the summer.

3. A caller has cherry trees that he planted in the spring. Now the leaves have wilted and died back. Why did this happen?

A. After discussion it was determined that the trees were purchased from a mail-order service and were delivered bare root. He planted them within a day of receiving them, which is advised because they will dry out quickly with no root ball to hold water. It was advised that he scratch the bark on some small twigs to see if it is green underneath the bark which means the tree is still alive. If under the bark is brown, the tree is dead. It could be an issue from the nursery or through the shipping process. It would be better to purchase trees locally.

He also wanted to know if he could remove the cedar trees on his property to eliminate the problems from cedar-apple rust?

A. No, the spores from cedar-apple rust will spread up to 2 miles. Removing the close cedar trees won’t stop the disease because it would be nearly impossible to find a location in Nebraska where you can get more than 2 miles away from a cedar tree. It is best to just spray susceptible apple trees or plant new trees that are resistant to the disease.

4. This caller has a weed called pineapple weed. Can you use a granular herbicide to control it?

A. Pineapple weed is an annual plant that is often found in poorly maintained areas, typically along driveways or along gravel areas. This weed can easily be controlled earlier in the season with a pre-emergent herbicide such as dimension or another that contains dithiopyr. For post-emergent control, glyphosate products such as Roundup could be used. The granular herbicide will likely not be very effective on pineapple weed.

5. A caller has strawberry plants that are producing very small berries and not a lot of those. It was hit by herbicide drift at one point, but seems to be recovering. Is the herbicide causing problems with fruit production or why are there so few berries that are so small?

A. The herbicide drift may impact the fruit development if it was hit while it was flowering that could have damaged the flowers before they were able to produce fruit. Otherwise, the small fruits are fairly common for the everbearing types of strawberries. Since they continue to produce through the season they will not produce the larger fruits that June bearing plants would have.

2019-06-21 10.46.37
Hollyhock rust, underside of leaf

6. A walk-in listener has a hollyhock plant with a lot of brown spots that are raised bumps on the underside of the leaf. What is causing that?

A. This is hollyhock rust. This is a common problem for hollyhocks, especially in this wet year. Remove the heavily infested leaves if you cannot remove all infested leaves and destroy those. You can use a copper fungicide on the plants to reduce the spread or re-infestation. At the end of the season, be sure to clean up all the leaves and plant material to reduce overwintering location to see less of the rust next year.

She also wanted to know what would cause a row of holes in her canna leaves?

A. This would be from Canna leaf rollers, a caterpillar. They can be controlled with a systemic insecticide applied to the cannas early in the season before the damage begins or by using Bt or Sevin once the damage begins.

7. This caller has an ash tree she would like to save from Emerald Ash Borer. What can be done now to ensure it lives?

A. Wait until Emerald Ash Borer is found within 15 miles of the tree prior to beginning treatments. Treatments are not necessary for an insect we haven’t found in the area. Even if defoliation has began on the tree when it is first identified in the area, treatments can be successful. Each time trunk injections are done they wound the tree leading to more problems.

8. How do you eliminate woodchucks from a garden?

A. They can be deterred with the use of a heavy-duty fence around the garden. The fence needs to be 3 feet tall and made of 2 inch mesh woven wire or heavy poultry wire. They can also be trapped using apples or carrots as bait. For more information on Woodchucks, view this guide.

9. Can you grow an avocado tree in Nebraska?

A. This would have to be an indoor tree. They will not withstand Nebraska winters outdoors.

10. A caller has wild roses that have some dead stems throughout the plant. Should those dead stems be removed?

A. Yes, you can cut out the dead canes of the shrub at any time.

He also wondered about tiger lilies. They were constantly mowed last year and haven’t come back this year yet. Will they come back?

A. If they haven’t regrown yet, it is likely that they have died. I would suggest replanting.

11. This caller has a big, green leafy plant that grows 4 feet tall and 6 feet wide with leaves similar to rhubarb plants. What would that be?

A. This sounds like Common Dock. It can be mowed off or sprayed with a roundup or glyphosate product now. In the fall, you can treat the plant with a 2,4-D product.

12. The last caller of the day has roses with holes in the leaves. What is causing that?

A. This is likely due to rose slugs. They are a common issue right now in roses. They will likely be finishing up their damage cycle soon and then they will pupate and become adult sawflies. The damage is minimal and they don’t need to be controlled with an insecticide which could harm pollinators coming to the rose flowers.

Yard and Garden: April 28, 2017

Yard & Garden for blog, 2017

This is the Q&A for the Yard and Garden show for April 28, 2017. 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 28, 2017. 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: Dick Campbell, Owner of Campbell’s Nursery in Lincoln, NE

1. The first caller of the day has a Lilac that has bloomed in the past, but it isn’t blooming much. It has never been a reliable blooming shrub. What is wrong with it and how can it be fixed?

A: This plant was bloomed a few times in the fall, which would cut off the blooms for the following spring. However, this isn’t the only problem because for the past couple of years they have been better at timing their pruning. A late frost could have hit the blooms causing problems with bloom, it may reduce the overall bloom amount. Also, this could be a nutrient issue. A good fertilizer, such as bone meal, could be incorporated into the soil surrounding the plant to help with the nutrient availability.

2. A caller has ribbon grass that has died out in the center. This dead center has continued to get larger over the years. What can be done about that?

A: This plant needs to be divided. Many perennial grasses will develop a dead center when it is time to dig them up and divide them. The spring is a good time to do this for grasses. Iris plants will do this as well, they are best divided and replanted in the fall.

3. This caller has a weeping Norway spruce that is bending over heavily. Should it be trained to keep it more upright?

A: This is a typical growth habit for a weeping Norway spruce. They bend over more than some of the other weeping varieties. It would be good to put a small stake along the trunk of the tree to support it for more upright growth.

This caller also wanted to know what the timing was for spraying apple trees for Cedar-Apple Rust?

A: Now would be a good time. When the galls on the cedar rust have come out to look like a slimy glob in the spring rains it is time to spray. Those galls have just begun to open up and release the spores. For more information on cedar-apple rust, see this NebGuide.

Photo of Cedar Apple Rust Gall photo courtesy of Mike Lewinski via Flickr Creative Commons License

4. A caller has a cherry tree that has a split going up it and now it has sawdust around it on the ground.

A: Often we see insects in our plants as a secondary problem. What you are dealing with here, is most likely carpenter ants. They have come into the split in the tree and are making a nest in the rotting heartwood. The carpenter ants are not doing any more damage to the tree than what is already done. They can be killed by using an insecticide dust in the tree crack, such as sevin. However, the more concerning issue is the crack in the tree. If the tree is very large it may be a hazard. Tree removal may be necessary. If the crack is not very deep, it could be a frost crack which would be less hazardous.

5. Can you grow English Walnuts in Nebraska?

A: Yes, they can be grown here, it is most likely you will have to plant them from a seed as there aren’t many grown as plants for sale. Check with the Nebraska Nutgrowers Association for more information and seed/plant sources.

6. This caller has a blue spruce that is not growing well. It was planted 17 years ago and hasn’t grown more than a couple of feet in this time. What is wrong and can it be fixed?

A: The tree could be battling with too much brome grass growing around it and competing for nutrients and water. It would be beneficial to kill the brome grass and to add a mulch ring of 2-3 feet out and 2-3 inches deep around the tree to help reduce competition. This also could be a root issue that there would be no fix for. Often times, our trees are planted too deeply or grown in a container too long causing the roots to circle the tree. Once the tree is planted, there is no way to fix these conditions and the damage may not be present in the tree for 10-15 years after it was planted. This could be the case with this tree. Try adding mulch and ensuring proper irrigation through the growing season and it may come out of it.

7. A caller has a redbud that is 8 years old. The branches are dying and there are holes in the trunk. It seems that only one branch is still alive on the tree. What can be done for the tree? Or should it be removed?

A: The holes could be from borers that can be treated, but are often a secondary pest. If only one branch is left alive on the tree, it may be time to replant.

8. This caller is planting a new garden in an area that was a cornfield until this year. What do they need to do to the soil to plant in it?

A: Because this has been used as a crop field, I would advise a soil test to see where all the levels of pH, organic matter, Nitrogen, Phosphorus, and Potassium are at and to ensure vegetable crops will even grow in the soil that has been heavily planted for many years.

9. A caller is cleaning out dead and dying pine trees in a windbreak. Do the stumps need to be removed? What can be done to get it ready to replant?

A: If they are Junipers, or eastern red cedars, they can simply be cut off at ground level and they will not regrow. With some of our windbreak plants, they may need a stump treatment of 2,4-D or Roundup or a mix of the 2 products. If you are planning to plant a new windbreak where you removed these plants, it would be beneficial to grind out the stumps. If there is enough space, you can replant around the old stumps, just stay a few feet away from the stumps left behind if you don’t remove them.

10. What is the best care to give to seedling trees given to students for Arbor Day?

A: Grow the seedling in a pot for a year. When winter comes either plant the pot in the ground with heavy mulch or bring the container into the garage. Next spring, plant the seedling into the ground and protect it with fencing from rabbits and deer.

11. A caller wants to know how to control sandburs and where you can purchase milkweed plants?

A: Sandburs are controlled with crabgrass control products. As a preventer, using crabgrass pre-emergent herbicides will also prevent the germination of sandburs. If they have already germinated and are starting to come up, you can use a post-emergent herbicide for crabgrass such as quinclorac or Drive or Dimension. You should be able to find Milkweed plants at many local nurseries.

12. This caller has a white powdery substance on her peonies. What is it and what can be done for it? Also, she has a cherry tree that was severely damaged from deer, but now there are new suckers growing from the ground around it. Can those cherry tree suckers be grown into a new tree?

A: The white substance on the peonies would be powdery mildew. It is not very harmful to the plant. You can use a fungicide on it to control the spread of the disease. Also, make sure you cut off and remove the above ground growth that dies back in the fall to reduce the spores that overwinter for next year. The cherry suckers may not come up as the same species as you had planted and they may not be strong growing. Many of our fruit trees are grafted for a strong root system but desired traits from other trees. When suckers grow from the roots, you only get the type of tree that the main root system was and not the more desirable traits from the above ground portion of the plant. You can try it if you have room, but otherwise it would be best to start over from a new tree.

13. A caller put preen on his garden earlier this spring to stop the weeds. Now he is concerned if the plants he starts from seed this year will grow?

A: Unfortunately they will not grow where the preen is without extra care. You can either plant these plants from transplants or as seed in another location or in pots or you can till the bed to destroy the preen that is working as a barrier in the garden. Once you have gotten seeds to start growing in the garden, you can reapply the preen to reduce weeds later in the season.

14. A gentleman has holes around his house that are 1.5 inches in diameter and his tulip bulbs have been eaten off. What would cause these holes and how can the “critter” be managed?

A: This could be from either 13-lined ground squirrels or from voles. If it is voles, there would be runs in the lawn. Place a couple of snap-type mouse traps perpendicular to the runs in the lawn to manage the voles. If it is 13-lined ground squirrels, see this publication from UNL.