This is the Q&A for the Yard and Garden show for April 10, 2015. 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, 2015. 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: Dick Campbell from Campbell’s Nursery in Lincoln, NE
1. The first caller wanted to know when to trim trees?
A: This depends on the type of tree to be trimmed. Oaks should not be pruned from April 1 through mid July to avoid susceptibility to Oak Wilt, a deadly disease that affects oak trees. Maples and birches will bleed sap excessively if pruned right not. This bleeding is not damaging to the tree, but it can be messy. Otherwise, it is good practice to prune deciduous trees during the dormant season so you can see through the trees to any crossing branches and air flow through the canopy.
2. This caller has a peach tree that produces too well. He wanted to know how to make the tree produce less fruit?
A: Fruit thinning should occur on fruit trees to help avoid branches breaking later in the season if they get too heavy due to fruit. The fruit on any fruit tree should be spaced 6-10 inches apart, leaving only one fruit on the branch every 6-10 inches. This will give you nice sized fruits that will not weigh down the branches.
3. A gentleman has ash trees that are loosing bark off the trunk. What would be causing this and how can it be fixed?
A: This could be caused by frost cracking. Frost cracks occur due to rapid temperature changes during the winter months. There is no cure for a frost crack and they may never heal over. Some trees may be able to close this wound, but if not it is an area where decay can enter the tree, as well as insects and diseases.
4. This caller uses ammonium sulfate on their lawn. Can this harm his lawn?
A: This can be harmful to the lawn, if the fertilizer is not spread uniformly throughout the lawn. If it gets concentrated too high in one are of the lawn, a burn can occur on the turfgrass. Otherwise, it will work fine as a quick release fertilizer.
5. Another caller has a steep slope in full sun in his lawn. What is a good perennial groundcover to use that does not have to be mowed?
A: Buffalograss is a good low management, perennial groundcover for full sun that wouldn’t have to be mowed. There are a lot of new varieties to choose from including, the newest from UNL, Sundancer Buffalograss that is darker green, has a denser canopy, and establishes faster. For more information on buffalograss care, see these UNL NebGuides: Establishing Buffalograss Turf in Nebraska and Management of Buffalograss Turf in Nebraska
6. This caller had old Lilac bushes used as a hedge. She had cleaned them up and noticed there was a lot of dead branches and some new growth of branches. What should she do to clean them up and get them growing nicely again?
A: Prune out the dead canes, leave as much of the new, healthy growth as possible this year. Over the next few years, she can prune more of the larger, older canes out to bring it back to healthy growth. Don’t use a rejuvenation pruning with these lilacs because the older they are the harder it is for them to come back from such a drastic pruning. Watch out for borers and use systemic insecticides if holes are found at the base of the shrubs.
7. This caller had locust trees in the roadside. What should she do to get rid of them?
A: Cut the trees down and do a stump treatment with herbicides labeled for use on trees in a roadside.
8. A caller wanted to know what to do when planting new strawberry bushes and if they can be planted in containers? He also wanted to know what to do with shrub roses that grew taller than they should have, how much can he prune off of those roses?
A: Plant the strawberries to where the crown of the plant is just at the soil surface. Plant them 1 foot apart within the row and space the rows 4 feet apart. After planting you can use a pre-emergent herbicide on them to reduce weeds. Yes, they can be planted in a container, but that container will need to be protected through the winter months to get the strawberries to overwinter. As for the roses, you can cut those back to 6-8 inches tall rather than just taking a few inches off of the top. This will give you new growth that will produce more flowers throughout the entire shrub rather than some flowers just on the ends and sides.
9. This caller had bagworms on his blue spruce in the past. He has now noticed that the top few feet of the spruce has died. Is this due to the bagworms? How can this be fixed?
A: This would be from a fungal disease called canker that is very common to spruce trees. From the point of the canker and anything above it, the tree will die and sap will flow from that canker location. There is no cure for canker, but the infected area of the tree can be removed to a location below the canker. It may regrow a new leader, but it may also continue to grow with a flat top. Bagworms can be treated with Bt, carbaryl, permethrin, or malathion around the third week of June or when the bagworms are immature and crawling around on the tree.
10. A caller wanted to know when to prune shrub roses? She also has a weeping white birch, when should this be fertilized?
A: Shrub roses can be pruned now. The weeping white birch should be fertilized just before they start to send sap up throughout the tree, which will begin soon. Watch all birch trees for borers, as this is a common pest in birches. Systemic insecticides, such as those containing imidacloprid, can be applied in the spring to help with borers in the tree.
11. This caller had apple trees that are 15 years old. When should they be sprayed for insects and diseases and what should they be sprayed with?
A: Orchard fruit tree sprays can be applied to all fruit trees. These have an insecticide and a fungicide to help with many problems that fruit trees face in Nebraska. This product should be applied at petal fall and every 10-14 days following. Be careful to not use insecticides on fruit trees while the flowers are blooming so no harm comes to the pollinators helping fruit development.
12. A gentleman wanted to know how to control Star of Bethlehem?
A: Spray with a combination product, such as Trimec. September 1st would be the prime time to do this so that the chemical will be taken into the bulb when the plant is taking nutrients into the bulb to help it get growing the following spring.