This is the Q&A for the Yard and Garden show for July 21, 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: Sarah Browning, Nebraska Extension Educator in Lancaster County
If you enjoy reading my Q&A from the show each week, take my quick survey at: http://go.unl.edu/44qr and be entered to win a free plant book or some free UNL gifts.
1.The first caller of the day wants to know how soon they should spray for fleas outside for an upcoming camping outing?
A. Sprays for fleas will last a couple of weeks, so it would be most beneficial to spray a week ahead of the event. Using a product containing permethrin or bifenthrin would be the best control.
2. A caller has hydrangeas that are healthy looking and green but they are not blooming, why is this?
A. This could be due to a few different factors. It could be that the plant is just slow to bloom this year due to environmental factors. Give the plant time to see if it does bloom. If the lawn surrounding the plant is highly fertilized, it may be that some of the fertilizer got into the rootzone of the hydrangea plants. Lawn fertilizers are high in Nitrogen and will cause the plant to grow nice, large, green leaves without putting any energy into producing flowers. If this is the case, make sure that you stay back away from the hydrangea next year when fertilizing the lawn. Finally, this could also be due to the plants being crowded and needing to be divided to allow the plants room to develop fully and produce flowers.
3. This caller has lilac shrubs that had not bloomed for the past few years but now this year it did finally bloom. What would cause that and how can she ensure that they bloom every year?
A. The fact that they bloomed again this year is hopeful. If lilacs are pruned at the wrong time of the year, such as in the fall or early spring, the buds will be cut off when this is done. However, the caller said she has not been pruning them at all. This could be due to the lilacs getting overgrown and having old, unproductive wood in the shrubs. It might be best to try to do a rejuvenation cutting to start all of the branches off new again. With a rejuvenation cutting, the entire plant is cut off about 6-8 inches above ground level removing all diseased, dead, and weak wood from the plant.
4. When do you divide lilac shrubs?
A. This is a woody shrub and we don’t typically divide woody shrubs due to the way that they grow. However, you can dig up the suckers that grow off the main plant and pull them out and plant them in a new location. The best time to do this replanting would be in later September when the temperatures have cooled off.
5. A caller has mum plants that have leaves that are shriveling up and turning yellow. There is only a couple of the plants on each side of her house out of a large group of mums that are not as full and not doing as well as the others. She hand-waters every day.
A. Watering daily could lead to a root rot. The roots need time to dry out between waterings. If it is a root rot, there is nothing that can be done to fix the damage already done and the plants will likely die.
6. This caller has a Rose of Sharon that is not blooming. It is planted in a location with minimal sunlight, would it be in too much shade?
A. Yes, Rose of Sharon bushes need full sunlight and will not bloom if in too much shade. This fall would be a great time to move it to a location with full sun.
7. A caller has cucumber plants with brown spots on the leaves. What would cause this and how can she avoid it killing her plant quickly like it did last year?
A. This could be a fungal disease common in cucumbers this year such as anthracnose or alternaria. Fungicides are not usually recommended in home vegetable gardens because they are typically not necessary or worth the time and money. However, if this disease quickly killed your plants last year, you could spray them with a liquid copper fungicide to keep the disease from spreading this year and killing your plants again. If they died quickly, it could also be from squash vine borer or squash bugs which can kill a plant almost overnight. Spray with a general insecticide for these insects such as sevin, eight, or bifenthrin. Wait the proper amount of days after spraying chemicals before harvesting vegetables. This time will be on the label as the PHI, or post-harvest interval.
8. This caller has a cherry tree that has a white fungus growing out of the trunk of the tree. There are no leaves on the branches in the middle of the tree and it hasn’t produced any fruit this year. What is wrong with the tree?
A. This is a shelf fungi, also called conks, appearing on the tree. Shelf fungi are the outward appearance of interior decay within the tree. When shelf fungi appear on the tree, the tree is dying and should be removed.
9. A caller has a burning bush that is growing up against the deck and some of the branches are dying in the center of the bush. Can it be pruned to remove the dead wood and to cut it back so it doesn’t block the deck? If so, when can it be pruned?
A. You can remove dead branches anytime, healthy branches should be pruned back in the late fall to late winter. The branches may be dying out due to scale insects which can get on the branches and reduce the vigor in the branches they are living on. If you find scale insect, use a systemic insecticide such as one containing imidacloprid in the early spring.
10. This caller remulched their garden this spring with a wood chip mulch. Now there is a cream colored substance on the mulch that looks like cat vomit, but they have no cats. What is this?
A. This is dog vomit fungus. It is a fungal structure much like a mushroom or puffball. It is not harmful to the plants or the mulch. It can be found on mulch because it lives on decaying organic matter such as the woodchips. It is nothing to be worried about and if you don’t like the way it looks, you can wash it off with the jet setting on your hose end sprayer.
11. A caller has a prairie area where he is trying to grow a mix of wildflowers and native grasses. However, Marestail is growing in among the desirable plants. How can he control the broadleaf weeds and not kill his desired broadleaves and grasses?
A. Once the grasses and wildflowers thicken up in the prairie, they will push out the weeds, but establishment is the hardest part. Mowing this year will help to thicken up the plants growing there and will stop seed production in the marestail which is an annual weed.
12. This caller is also starting a prairie area. He has had a 2 acre pasture of alfalfa that he now wants to change over to native grasses. What is the best method of doing this?
A. The native grasses are mostly warm season grasses, so they are best planted in the end of May to the beginning of June. Dormant seeding could be done in late November, but you need to prepare the area this fall before a dormant seeding is done. To prepare the soil, kill the existing plants this fall and clean up and aerate the soil prior to planting. You can drill the seeds in when the time comes as well.
13. A caller has an area where soil was added and leveled off. How do they overseed the area that has been overtaken by weeds at this point?
A. Spray the area with roundup to kill the weeds. You can spray now and again shortly before seeding the area. Then overseed in September with a Kentucky bluegrass or Turf-type tall fescue. Once you overseed, use a rake to get the seed to contact the soil and keep it well watered.
14. This caller has an oak tree that is not fully leafed out, the top is bare and the lower leaves are smaller. What is wrong with the tree?
A. This could be due to herbicide drift since many neighboring trees look similar. If so, there is nothing to do to fix herbicide drift once it has been done, just make sure the tree is being watered and that it is mulched in. This could also be due to the fact that the tree isn’t getting enough deep water if it is just being watered by the turf irriagation. Make sure that once every 10-14 days a slow, long irrigation is done around the tree. Trees need water down to 12-18 inches deep, lawn irrigation only waters the top 4-6 inches of the soil.
15. A caller has 2 large Norway pines. How can he get grass to grow under the trees?
A. Unfortunately, grass will not grow in heavy shade under a large tree. It would be best to try a groundcover, sedge plants, or shade perennial plants. We often continue to battle grass problems and overseeding in heavy shade, but the reason the grass won’t grow is because it is not meant to be grown in shade. In these situations it is best to find other plants that are more suited to the shade or just mulch around the tree to stop weeds from growing around the tree.
16. The last caller of the day has dwarf lilacs that are quite large. How tall are they supposed to grow?
A. Dwarf lilacs, such as the Miss Kim variety, will still grow up to 6 feet tall if left unmanaged. This is still much smaller than the full sized-lilacs which grow up to 15 feet tall. You can continually prune these lilacs in the spring after they finish blooming to keep them to a smaller size. Prune within the couple of weeks after blooming so you don’t cut any flower buds off.