This is the Q&A for the Yard and Garden show for June 16, 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: Jim Kalisch, Insect Diagnostician from UNL Extension
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1. The first caller of the day has a Daylily that has yellow streaks on the leaves. What is causing this? She also has Roses that are getting yellow leaves and sprayed a rose product containing both an insecticide and a fungicide. Will this work for the roses?
A. The daylilies likely have Daylily Leaf Streak, a fungal disease common on daylilies. It would be best to remove the infected leaves and destroy them from the plants as you see them and clean up the plants in the fall by cutting off all the foliage and destroying it for winter. It will also help to water from below the plants rather than using an overhead sprinkler. Also, it sounds like her daylily plants are overgrown, this fall it would help to dig and divide them to increase air space. As for the roses, they could be dealing with black spot or rose slugs. The fungicide and insecticide combined product will work to reduce the incidence of both of these problems.
2. A caller wants to know when the best time to transplant asparagus and what can be done for a cypress tree turning yellow?
A. Asparagus is best planted and transplanted in the spring. However, if this is an old patch of asparagus, it would be better to just start from new crowns. Either way, you need to wait 3 years to harvest to allow the roots to develop. Trees that turn yellow instead of their deep green color through the growing season are often lacking iron. The best management for Iron chlorosis is to use a trunk injection of iron. However, with cypress trees, it is often difficult to get them out of this condition and multiple years of trunk injections can start to stress the tree out to the point of death in some cases.
3. This caller has peonies and moonflowers in her yard and wants to know when the best time is to transplant them and how to prepare the area that was rocked to get these plants to grow well?
A. Spring will be best for establishment, but fall would be a second best option to transplant these plants. Remove the rocks that were in the new location and then till the soil, adding compost in as you till to improve the structure of the soil and add some nutrients back into the soil. When moving peonies, make sure that it is planted at the same depth in the soil, to deep and the plants will not flower. After you have planted, add some wood chip mulch around the plants to help them stay cool and hydrated. Water as needed.
4. A caller has a large blue spruce that has some browning on the needles and those needles are beginning to fall off the tree. This has started at the bottom of the tree and is moving upward through the tree. What is causing this? Can her tree be saved?
A. This could be one of two things, either a fungal disease or spidermites. After discussion, the caller stated that the needles are more of a reddish brown, which is distinct for a fungal disease called Rhizosphaera, which is common now. The trees can be sprayed with a fungicide to reduce the spread of the disease. Over time, the trees will grow new needles.
5. This caller recently planted 2 new 7-feet tall blue spruce trees. They are watering these trees at least once a week for 30 minutes and they are mulched in with straw. Now, the lower branches are droopy and wilted. Do these branches need to be removed?
A. These trees are dealing with transplant shock and need some time to build some new roots and get over the shock. Leave the branches for now and continue to water as needed.
6. A caller has a volunteer tomato plant that is about a foot tall. Can it still be transplanted now to be grown in the garden?
A. Yes, it will still be fine. The volunteer tomato will not come true from seed, so it may not be the same type of tomato as what was planted last year, but it should grow fine.
7. A caller has a bald cypress that has needles that are curling. What would cause this?
A. This sounds like drift from 2,4-D or another type of herbicide. This would happen if people are spraying these herbicides now that the temperatures have risen so high. Slight damage may be only aesthetic this year. Multiple years of damage can start to cause stress and even death to the tree.
8. This caller is growing grapes in his backyard. These grapes have black spots on the vine that the caller sees most years. The grapes then shrivel up before they can be harvested. What would cause this?
A. This sounds like a fungus. It would be best to get on a fungicide schedule with your grape plants to keep this fungus from returning every year. For more information on when and what to spray, view the Midwest Small Fruit and Grape Spray Guide
9. How do you stop zoysia grass from spreading in Tall Fescue and Kentucky Bluegrass?
A. Fall fertilization will push zoysia to grow when it is going dormant because it is a warm season grass. This fertilization will be beneficial to the cool season grasses.
10. A caller has Canna bulbs. Is it too late to plant them yet this year?
A. They can plant them to keep them alive and get sugars built up for next year, but they will likely not bloom this year. Cannas have to be dug up and stored indoors over the winter and if they are left out of the ground for 2 seasons, they may not have enough energy to grow after that. Planting the bulbs this year to get sugars for growth next year would be the best place for them to be stored.
11. This caller has patches of round grass in the lawn. How can it be controlled?
A. This is likely a perennial grassy weed such as windmill grass, orchardgrass, or quackgrass. These can be controlled with roundup and then overseeding or with a mesotrione product such as Tenacity. For more information on these weeds, view this article from Lancaster County Extension.
12. A caller has a spirea bush with dead wood in it. Can it be cut back now?
A. Yes, this isn’t the best time for a summer blooming spirea, but it will be fine. Summer blooming spirea’s should be pruned in the late winter, such as February and March for best blooms. This can be pruned back to 6-8 inches from the ground. However, if it is a 50 year old plant, as the lady stated, it may be getting old and may not return from a rejuvenation cutting as it may be dying due to old age.
13. How do you get rid of poison ivy which is growing in rose bushes?
A. It will be difficult to remove the poison ivy and not harm the roses or not get a medical reaction from the poison ivy while working to remove the posion ivy. Paint roundup on the leaves of the poison ivy now, being careful not to get the glyphosate on the roses. It may take multiple applications to kill the poison ivy entirely. Wear long pants, long-sleeved shirt, gloves, socks, and shoes when applying this to avoid getting a rash from the poison ivy.
14. This caller has a trumpet vine that is creeping into the lawn. How can it be controlled in the lawn without damaging the parent plant?
A. Just keep mowing it off. These are likely runners from the main plant and if a pesticide is used to control the runners, it will go through the plant into the roots of the main plant.
15. This caller is curious if poison ivy oils can transfer to pine cones on the ground surrounding the poison ivy plants? She is also curious if she can trim her Iris plants back now or if she has to wait until the fall?
A. According to Clemson University, the poisonous oils can remain active for months on objects. It can be picked up on tools, clothing and the fur of pets. Anything that may carry the oil should be carefully washed. Even dead plants or roots may cause allergic reactions for a couple of years. So it is best to clean the pine cones that came in contact with the poison ivy. For more information, see this guide from Clemson
As for the Iris plants, you need to wait until fall to cut the leaves back when the leaves turn brown for the year. It gives the plant time through the summer to build up sugars to help bloom early next spring.
16. What type of tree would be recommended that is smaller but provides good shade?
A. Dwarf Chinkapin, Pawpaw, Redbud, Crabapple, Serviceberry