This is the Q&A for the Yard and Garden show for July 14, 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: Steve Karloff, District Forester from the Nebraska Forest Service
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 has overgrown Forsythia and Yellow Dogwood plants. What can be done for pruning to reduce the unproductive plant materials and when can it be done?
A. Because these plants are overgrown, it would be most beneficial to do a rejuvenation cutting on them. A rejuvenation cutting is when you prune a shrub back to about 6-8 inches from ground level and remove the majority of the top growth. This will get rid of all the old, unproductive wood to bring in all new, younger wood that will be more productive to leaf out better throughout the entire shrub, will lead to more flowering, and will be healthier and free of insects and diseases that were problematic on the shrub. It is best to prune forsythia immediately after they flowered, but it could be done in the fall. Remember with a rejuvenation cutting that the plants will not flower for at least 2 years following the heavy pruning.
2. A caller has blue spruce trees planted in an area near a lake. Some of the spruces are 60 years old and some are 15 years old, all are dying from the bottom up. What is wrong with these trees?
A. Too much moisture can cause blue spruces to die from the bottom up, since they are planted close to a lake, they may be getting too much watering. When replacing the trees, choose a species more adapted to wet locations such as white pine, cedars, or bald cypress.
3. This caller has a green apple tree that was planted before he moved in and the apples are falling so they are ripe. The apples are not juicy and are quite porous and pithy. What is wrong with the apples?
A. After discussions on this with Paul Hay, this is just the variety of apple that is growing there. This is an apple that is used more for processing to be used in pies and sauces and not for fresh eating.
4. A caller has rabbits that are eating her hostas and lilies. What can be done to control them?
A. The only effective management for rabbits in a garden is to put up a fence that is at least 2 feet high.
5. This caller has a bur oak that was planted in the spring. The old leaves on the tree are turning brown but the new growth is green and healthy looking.
A. Be careful to not overwater a tree, especially with newly planted trees. These young trees have a small root system and do not need to be watered as heavily as an older, established tree. It is beneficial to allow the roots to dry out a little between waterings.
6. A caller has white pines that were planted too close to the driveway and now the branches hit cars when they come to park in the drive. Can the branches be trimmed back so they don’t hit cars and when can that be done?
A. Yes, these branches can be removed. Take the branch all the way back to the trunk so that they don’t regrow causing pruning to be necessary every couple of years. You can prune evergreens most any time of the year.
7. This caller has a bur oak that was planted last fall. It didn’t come out of dormancy this spring and has not grown. However, there are suckers coming up at the base of the tree, can the main tree be pruned out and the suckers allowed to grow into a new tree?
A. Yes, remove the main tree and allow one of the larger more upright suckers to grow into a new tree. However, sucker growth is not always as strong as the tree itself, so it may not perform how the tree was supposed to.
8. Can lilacs be pruned now?
A. No, it is best to prune lilacs within a couple of weeks after they are done blooming. Lilacs produce their flower buds in the summer and fall of the year before they bloom, so pruning now would cut off the flower buds for next spring. To ensure flowering for next year, wait until after it blooms next year and then prune it back at that time.
9. A caller has cypress trees that were planted 5 years ago. One of the 2 trees is in great condition with good color. However, the other one is smaller and yellow in color. The trees are only a few feet apart. What is wrong with it and can it be fixed?
A. The yellow and shorter tree may have just been a bad tree out of the gate. Sometimes our trees develop a problem in a nursery or from the seed source and never really overcome that. Also, with Bald Cypress trees, it is hard for them to overcome iron chlorosis. When these trees get iron chlorosis, they become stressed and no matter how many trunk injections, which also harm the tree, they never come out of the chlorosis. At this point, it would be best to remove and replace the bad tree.
10. This caller is having problems with their lawn. He fertilized it in May but now it has brown patches throughout. How much water does a lawn need and how can he improve his lawn?
A. Our lawns need 1-1.5 inches of water per week on average to stay green and out of dormancy. The patches could be the lawn going dormant or they could be from a fungal disease. There are a lot of summer fungal diseases such as brown patch, summer patch, and dollar spot. They are common in the hot and humid days in late summer but as soon as that weather fades, the brown spots will turn green again. For more information on these diseases, see this TurfiNfo from UNL.
11. A caller has Bradford pears that have branches coming out 1.5 feet above the ground, should those be removed or will they move up as the tree grows? The trees also have suckers, what should be done about that?
A. If these low branches are in the way for mowing and you don’t like how low they are, they should be removed. Remember not to remove more than 1/4 of the tree in one season, so you may have to remove one this year and another next year. Those branches will always be at that level, though, so if they are in your way they need to be removed. As for suckers, cut those off at ground level and don’t treat them with anything or the spray will kill the tree as well.
12. This caller has pumpkins in his garden that are wilted during the day but at night they look fine. What is wrong with the plants?
A. If a plant looks better in the evening or in the morning but is wilted during the hot part of the day, it is heat or water stress. Make sure your plants are properly watered through this hot and humid couple of weeks of the summer.
13. A caller has tomato plants with leaves that are drying up from the bottom of the plant. The tomatoes are also rotten on one end of the fruit. What is causing these two problems?
A. Ensure that the plants are being properly watered. Vegetable gardens need 1-1.5 inches of water per week. Hand watering at the base of the plant every night is not sufficient for the root system. The plant could also be exhibiting early blight which is common right now. Remove the infected leaves, the disease will fade soon. The rotten side of the fruit is blossom end rot. This is a calcium deficiency in the plant caused by uneven watering making the calcium unavailable to the plant. Adding calcium to the soil will not help the problem, just make sure your plants are well watered and mulched in. Blossom end rot will fade soon. You can eat the good side of the fruit and dispose of the rotten end.
14. This caller has round berries on the plants of her potatoes. What are these?
A. These are the fruits of a potato plant. We typically do not see the fruits because we are growing the plants for the tubers produced underground and we harvest before the fruits appear. Remove the fruits so the plant can build the tubers.
15. A caller has roses that have uniformly round holes on the edges of the leaves and brown spots. He sprayed with rose spray and it is not working. What is wrong with the plants and how can he fix it?
A. This is likely damage caused by the leafcutter bee which is a pollinator and beneficial insect. There is no need to control this insect. Here is a great article from Jonathan Larson, Nebraska Extension Entomologist, on Leafcutter Bees.
16. How do you control puncturevine in a lawn?
A. Use a 2,4-D product in the pre-bloom stage. Management will not be achieved this time of year because the plant is large and will be difficult to kill. Also, don’t use 2,4-D products in the heat and humidity of the summer or the product may move to non-target plants causing damage.
17. How do you control moss in a pond?
A. Copper sulfate crystals can be used for control. For more information on pond management, visit the Lakes, Ponds, and Streams section of the water.unl.edu website.
18. A caller has apple trees that get insects in the fruit every year. When and what should they be spraying for that?
A. It would be best to get on a spray schedule, spraying with an orchard fruit tree spray every 10-14 days throughout the growing season. For more information visit the Local Food Production page within the food.unl.edu website for spray guides.
19. The last caller of the day has vines with milkweed type pods growing in his fenceline. What can be done to control it?
A. The plant sounds like honeyvine milkweed. At this point of the year, pull it or spray it with roundup. In the spring or fall, 2,4-D could be used, but not now due to the heat and humidity.