This is the Q&A for the Yard and Garden show for May 6, 2016. 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 5, 2016. 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: Jennifer Morris, Forest Health Specialist for the Nebraska Forest Service
1. The first caller of the day has peach, plum, and apple trees that were recently planted. Should she use tree spikes for fertilizer for the trees and when should that be done?
A. Fertilizer for a tree is usually not necessary in Nebraska soils. Let nature take its course to naturally fertilize the tree. Fertilizer should only be used on trees, or any plant, as it is necessary. A plant can be damaged or even killed if they have too much of a particular nutrient, so it is best to do a soil test prior to applying any type of fertilizer to your plant.
2. A caller has grasshoppers in his lawn and has problems with large populations in the past, but he also has beehives nearby where he would want to spray to control the grasshoppers. Can he treat the grasshoppers and not harm the bees?
A. Insecticides that are commonly used as sprays for grasshopper control are very toxic to bees. You should only use insecticides for the grasshoppers in this situation for serious situations where chemical control is necessary. If sprays are warranted, you would want to do so on a calm day so the spray does not drift to the bees and mow the lawn first to reduce flower heads present that could get pesticides on them to get onto the foraging bees.
3. There is a caller who wants to plant some new apple trees. The trees he currently has continue to face problems with cedar-apple rust. What tree cultivars should he choose that will not have the problems with this disease?
A. There are many apple trees that are resistant to cedar-apple rust. When planting a new apple tree it is best to go in with a tree that is resistant to this disease because cedar trees are common in Nebraska, which is the alternate host. This allows most any apple or crabapple tree to be vulnerable to the disease. For resistant cultivars, see page 3 of this NebGuide on Cedar-apple rust by Amy Timmerman.
4. A caller wanted to know if they can use Roundup (or other glyphosate product) in their garden to kill pampas grass? Can it be wiped onto the stalks of the plant and not harm the peonies or raspberries that are growing with the pampas grass?
A. Yes, it can be used among raspberries and peonies, but it needs to be carefully applied so that you don’t get it on the leaves or other plant parts of the desirable plants. Painting the glyphosate product onto the leaves of the pampas grass will work into killing the grass and will keep it from getting onto the desirable plants. Grass-b-gone may work for it in the peonies and can be sprayed directly over the peonies and cause no harm to them, however this product should not be used in crops that are used for food or feed.
5. A caller has a mum growing on the east side of their house and it didn’t come back. Why is that?
A. Some of our mums are not as hardy as others. This may have been one of the lesser hardy mum plants. This mum was also moved in the fall so it may not have been ready for the winter after being moved or it could be planted in a more exposed location. If there is no green showing in the plant at this point, I would assume it is dead and it is time to replant.
6. A walk-in clientele asked what the orange pods were on her cedar tree? She also wanted to know if she should remove the cedar tree or if she can treat it?
A. This is the gall of the cedar-apple rust disease. In the rainy portion of the spring these show up to release the spores of the disease to move to apple trees. This disease is not harmful to the cedar tree so no treatment and definitely no removal of the tree is necessary.
7. A caller wanted to know how to start a new plant from the family tree peony plant.
A. Prune off a branch of the peony and place it into rooting hormone and then into soil or into a pot of gravel that is kept moist to start roots. Once roots have begun, the plant can be planted into the ground.
8. This caller has a 12-15 year old apple tree that has bark on the trunk that is splitting on the southwest side of the trunk. What would cause this and is it harmful to the tree? He also has a tree that has holes in the trunk that are in a row and about the size of a pencil. What is this from?
A. The holes in a line on the trunk of a tree would be from a yellow-bellied sapsucker, a type of woodpecker. This is not harmful to the tree and has no management strategy. As for the bark splitting on the apple tree, this sounds like sunscald. This is a disease that occurs in the winter when the cells in the bark freeze and thaw quickly and bursts the cells causing the split. There is no control for this and the trees will typically live a long, happy life after this occurs but the scar will remain for the life of the tree.
9. The final caller of the day has a windbreak with evergreens that were planted 9 years ago and they are too close together. What is the recommended spacing for trees in a windbreak?
A. 14-16 feet between trees is the average spacing requirement at this point. You need to maintain that distance so that when the trees are full sized they don’t overlap each other too much which can cause more disease problems.