Yard and Garden: June 1, 2018

Y&G Blog Photo, 2018

This is the Q&A for the Yard and Garden show for June 1, 2018. 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 3, 2018. 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: George Pinkerton, Director of Landscape Maintenance for Downtown Lincoln

1.The first caller of the show wants to know how to control grassy weeds in peonies and in asparagus?

A. In the peony plants, you can spray Grass-b-Gon or another product containing fluazifop-p-butyl to kill perennial and annual grassy weeds. However, this product cannot be used in asparagus. For weed management in asparagus, it is best to use mulch through the season to keep the weeds down. Roundup, or glyphosate, can be sprayed over top of the asparagus in the beginning of the season before the asparagus begins to grow, after harvest once all the stalks have been cut off below the ground level, and at the end of the season after removing the ferns and no green of the asparagus is showing above ground. Preen that is labeled for use in asparagus can be used throughout the season as well to stop the germination of new, annual weeds.

2. This caller has ants on their potatoes and radish with a great deal of damage. What can be done to stop the ants from damaging these plants more?

A. It is likely that the problem is not due to the ants, they are likely there as a secondary issue and they are not eating the potatoes and radish. Grubs will feed on the tubers and other underground structures. They do not typically affect tomato roots or the roots of the other above-ground growing plants. There are no products labeled for grub control in a home vegetable garden. If the grubs are becoming a problem, move the garden next year and treat the area without the vegetables on that area for a year. Treat for grubs in the lawn around the garden to help reduce the population.

3. A caller has had poor pollination in cucumbers in past years. What can he do this year to ensure he has better cucumber production?

A. If there aren’t many bees or butterflies around the garden, it could be low pollination. Try to attract pollinators through additional pollinator garden areas. You can also hand-pollinate these plants with a cotton swab, touching many flowers throughout the plant with the same cotton swab to transfer the pollen throughout.

4. This caller purchased burning bushes in containers and then left for 4 days before getting them planted. Now, the leaves are brown and crispy, are these plants dead or will they pull through?

A. If branches are brittle and break rather than bend, they are likely dead and will not regrow from that. In the late May time frame, it is going to be difficult to keep a newly planted shrub watered well enough in this heat and drought, this will be even more difficult if the plant is not placed into the ground right away. Containerized plants would need to be watered at least once a day now that it is so hot.

5. A caller planted 2 fruit trees and a red maple that they received through a mail-order service. The fruit trees are doing fine, but the maple has not leafed out and is not growing well at all. What happened? Will the tree come through?

A. Sometimes during transportation, bare root trees will dry out and they are not able to recover from that. It is best to purchase your plants locally to ensure this does not happen.

Carpenter Bee, J. Kalisch
Carpenter Bee Photo from Jim Kalisch, UNL Entomologist

6. How do you control carpenter bees?

A. Carpenter bees are a good pollinator insect and will not sting you. If they are doing damage to the structure of a building, you can fill the holes with some caulk or putty. If you would like to, you can inject sevin dust into the holes before sealing the holes to kill the bees. For more information here is a guide from Lancaster County Extension on Carpenter Bees.

7. This caller has Siberian elms growing within a well-established windbreak that are dropping yellow leaves. What is wrong with the trees?

A. It is likely that the trees turning yellow are hackberry trees growing in the windbreak rather than the elm trees. Hackberry trees have recently been dropping leaves like they do in the fall. They tend to do this in the late spring if the weather becomes unfavorable to their growth. They will drop their leaves and then push new regrowth. This is likely due to the quick change to hot/dry this summer.

8. A caller just planted rose bushes and oak leaf hydrangea plants in full sun with a rock mulch. Now the roses have holes in the leaves and the hydrangea plants are getting rush spots. What is wrong with these plants?

A. After a picture was emailed, it was determined that the roses had rose slug damage. Rose slugs are actually the immature form of sawflies that feed on roses this time of year causing brown spots in the leaves and holes. Rose slugs resemble a caterpillar that is translucent green with a brown head and they are found on the underside of the leaf. They are not very detrimental and do not need to be controlled. They are a short-term problem. Also, it is difficult to control sawfly larvae and not harm pollinators in the flowers of the rose. The hydrangeas are exhibiting problems with heat due to being planted in full sun with a rock mulch. Make sure to keep them well-watered to avoid more problems.

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Creeping Charlie in a lawn

9. This caller has a mint smelling weed growing in his yard. What is it and how do you manage it?

A. This would be Creeping Charlie, also called ground ivy. This weed can be difficult to control, but it is best managed in the fall. Many broadleaf herbicides will work for creeping Charlie, including 2,4-D, trimec, tenacity, or triclopyr. It is best to apply one of these chemicals 2 or 3 times in the fall. One application can be made around September 15th with a second application around October 15th. It will take multiple years of this management plan to fully rid the yard of ground ivy.

10. A caller has zucchini leaves that are crisp and curled up rather than smooth like normal growth. What is wrong with the plant?

A. After discussion with the caller, it was determined that she should spread her watering out more. Our vegetable gardens need about 1 inch of water per week, but this should be spread out over 2 or 3 times per week if rain is not providing that water. She also sent a photo to Nicole, where it was determined that this might be due to herbicide drift from a broadleaf herbicide applied nearby. In the heat and humidity we are dealing with currently, it is best to not use broadleaf herbicides anymore now until the fall of this year to avoid volatilization of the chemicals where they turn into a gas and move around to non-target plants.

11. How much water does a lawn need? How do you know how much water you are applying? Should you water in the afternoon to cool the grass off or is that a myth?

A. A lawn need 1-1.5 inches of water per week. If you are not getting that naturally, it is best to apply 1/3-1/2 of an inch 3 times per week to keep the lawn healthy. You can do an audit of your system to know how much you are applying each time you water. Simply place tuna cans or some type of catch device throughout the lawn to catch the irrigation as it runs to determine how much is being applied each time. As for syringing the lawn, no it doesn’t really help the lawn cool off. Lawns transpire as a natural way to cool themselves, and syringing only cools the lawn a few degrees for a few minutes. For more information on syringing, here is a good Turf iNfo article from Bill Kreuser at the UNL Turfgrass Department.

12. This caller has something that is digging large holes in the yard. What would be causing this and how can the damage be controlled?

A. This could be due to a skunk digging up the grass looking for white grubs. Treat the lawn for grubs in the middle to late part of June to help reduce the attractant for the skunks. For more on skunks and how to control them, here is a guide from UNL Wildlife.

13. A caller is looking for a good plant to use to grow up a windmill. Would a vining hydrangea be a good choice to grow on the windmill that is in full sun?

A. No, hydrangea plants don’t grow well in full sun. Honeysuckle would be a good choice for this location. If you can keep the roots a bit shaded, clematis would be another great choice.

14. The final caller of the day wanted to know how long tulips can live?

A. Some of the newer varieties may not live as long as some of the old types. However most will grow for many years.