This is the Q&A for the Yard and Garden show for June 5, 2020. 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, 2020. 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: No guest host due to COVID-19 and social distancing
1. The first caller of the show would like to know when the proper time is to spray for bagworms?
A. After they have hatched, which is different every year, based on temperatures. It is typically around the middle of June. This week, the UNL Entomology department reported that bagworms have hatched in the Lincoln and Omaha area so if they haven’t hatched in Southeast Nebraska yet, they likely will in a week or so. We should be in the spray window for the next few weeks.
2. A caller has large trees in her yard that are shedding large amounts of leaves recently. What is causing this? Will the tree be ok?
A. This could be from a variety of factors. In some cases, the trees may have put on a large flush of leaves this spring. With the extreme heat and humidity recently, they dropped the extra leaves. They could also be leaves that have a minor leaf spot disease that has caused a large amount to drop off. Either way, the trees are still in good health with a full canopy of leaves and should be fine for future growth.
3. When can a large hosta be divided?
A. At this point for the year, it would be best to wait until next spring. It is now hot and windy so it would be very hard for the plant to tolerate being divided and replanted. Hostas are best divided in the spring before hot weather but after they have emerged well.
4. This caller has potato plants growing and now the edges of the leaves are curling up and turning brown. What is wrong with them?
A. The caller is watering his potatoes correctly, but does not use mulch. This could be one of two fungal diseases brown leaf spot or early leaf blight. Fungicides such as mancozeb or chlorothalonil can be used to control this, but the wet weather recently is likely the reason it is showing up. Mulching the plants will also help so that the spores don’t splash from the soil back up to the leaves of the plant. Be sure to clean up the garden at the end of the year and rotate the potatoes around to different areas of the garden each year.
5. A caller has tomatoes that the top leaves are tight and deformed. What is causing this and do they need to be replanted?
A. This is likely from herbicide drift, it is hard to say for sure without seeing the plants, but it sounds most like herbicide drift. This has started to become a problem again this year due to the change in weather. As we warm up, we see more problems with 2,4-D and dicamba products that turn to a gas and move to non-target plants. Tomatoes are very sensitive to drift from 2,4-D or Dicamba products. They should grow out of the damage, however because we don’t know exactly what product hit these tomatoes there is no way to know for sure when the product will be out of the tomatoes. I can’t say when or if these tomato plants will be safe for consumption this year.
6. This caller grew cucumber plants last year and the vines took over her small garden. Can she cut them back to keep them away from her other plants?
A. Yes, the vines can be cut to reduce the growth slightly. I wouldn’t cut too much off because that can reduce the yields. It might be better for her to use a bush cucumber in future years that will not spread as far. She can also try using a trellis to have the cucumbers grow up rather than out.
7. A caller has sapling trees growing up in her chain link fence. What can she do to kill them?
A. These should be cut off and treated with a stump treatment, painting a herbicide on the freshly cut stump. Roundup would be the best to use in this heat and around other plants. She asked about using a brush killer and this can be used, but shouldn’t be used too close to desired plants. Always read and follow the label when using pesticides
8. This caller was curious if bagworms would run their natural course and if he would be able to quit spraying his trees eventually?
A. Unfortunately, bagworms are here to stay. They will never fully go away. Bagworms, like all insects, go through peaks and valleys in their population and right now we are nearing the peak. This means we have very high populations that are doing damage to our plants. When the bagworm population drops, you may be able to discontinue spraying for a few years if the population isn’t large in your trees. For now, you will want to spray with the high populations.
9. What are the orange things on the cedars and what plants will they damage?
A. These are the galls of cedar-apple rust. This disease needs 2 hosts to complete its lifecycle. The galls are hard, gray/brown structures on the cedar trees over the winter. In the spring, when it rains, these galls open up to allow the spores to move to the apple trees. When the galls open up they are orange structures that resemble an octopus due to all the telial horns around the gall. The disease causes no problems to the cedar trees, but will cause lesions on the leaves and fruits of apple trees. If you have a susceptible apple tree, now is the time to spray with a fungicide to prevent the disease from affecting your tree. For more information, view this NebGuide.
10. Is there any reason to spray fruit trees this year since the blossoms all froze and no fruit will develop?
A. It wouldn’t be necessary, if you want to take a year off of spraying. The trees will still develop some damage on the leaves, but it shouldn’t kill the tree. For fruit trees in Nebraska, you can either spray throughout the entire summer to combat all the problems or you can not spray and have some problems. If there will be no fruit, it wouldn’t be necessary to spray the tree.
11. A caller has an old rose that bloomed but now the leaves look to be drying up. What is wrong with it?
A. It is hard to tell for sure without seeing the plant. There are a few different fungal diseases that could be affecting the roses now after all the rain we have seen recently. It may also be that the plants were shocked by the sudden onset of hot, humid, windy environmental conditions after the cool spring. They could also have damage from rose slugs, which are out right now. He also said they are surrounded by brome grass which could be causing competition issues. Most of these problems will fade on their own. If it is a fungal disease, there are rose specific fungicides that can be used. Rose slugs are minor problems and will go away as fast as they appeared, without chemicals.
12. The final question of the day was a caller who had planted a butterfly milkweed. overnight it was pulled out of the ground so he replanted it and it was again uprooted the next night. What is causing this? It is only on the new butterfly milkweed plant.
A. I assume this is damage from a squirrel or other type of wildlife. The best defense against wildlife damage would be to put a fence around the plants being damaged. There would be nothing else that would be very effective, or proven to work through research, in this case.