Q: It seems like every day during gardening season I have a bunch of questions, and I try to find the answers online but I’m not always successful. We’re so glad you are available to help!
We’ve got six Taunton yews, and in early spring I cut off the few brown branches that suffered from the winter weather and then I lightly pruned them. The yellow/brown branches that are shown in the pictures have occurred since then, so it is not sunscald from the winter. What’s causing this and what should I do? The yews have been in place for five or six years and have always been healthy. We’d hate to lose them. — Lori Keller, Barney, N.D.
A: We’re all in this together, so I’m happy to help in any way I can. You’re right, it is often difficult to find answers online, or to sift through all the possibilities.
Taunton is one of the more reliable cultivars of yew for our region, especially useful in shaded or partially shaded areas of the landscape. Like most evergreens, they can suffer winter sunscald or windburn, as you mentioned, especially if growing in exposed sites. Winter injury can be pruned from yews more successfully than some evergreen types, such as arborvitae.
Why did additional branches turn brown, even after you had pruned away the obvious winter injury? Winter damage isn’t always visible immediately, but sometimes shows up when trees and shrubs begin their spring growth.
Branches or other plant tissue can have unseen winter injuries, which make it difficult for those tissues to conduct water and nutrients when spring growth begins, and the needles or leaves then begin to show visible decline. An example is shrub portions that suddenly decline after beginning spring growth, and a closer examination shows that rabbits did a little winter nibbling along lower branches, yet not enough to be readily seen.
Chances are that your yews have some slight damage that is showing up, but I think they’ll be fine. Prune away any injury as it becomes apparent. To encourage fresh, new vigorous growth, apply granular 10-10-10 fertilizer around the yews now in early June, following label directions, and then water to activate. Please keep us posted.
Q: When is the best time to transplant asparagus? We have some at an old farmstead we wanted to relocate. Someone also told us in the fall you should burn the tops off. Is that right? — Julie Levos.
A: Asparagus can be dug and transplanted either in fall around Labor Day, or early spring before any growth starts. The least successful time is when the asparagus is actively growing, May through August.
Instead of burning the above-ground tops or cutting them down in the fall, it’s better for the asparagus if they remain intact over winter. The old growth catches insulating snow, and the plants generally survive winter better. Cut the tops down to ground level in early spring before new spears appear.
Q: What are the unsightly bumps on the leaves of trees?
A: My mailbox is full of photos of tree leaves showing raised bumps. The bumps are called galls, and are caused by tiny insectlike mites that have enclosed themselves in a protective little bubble of hard leaf tissue. The good news is that these galls are mainly cosmetic, and they don’t affect tree growth unless about three-fourths of every leaf surface is covered completely with galls.
The galls bother humans more than they do the trees, and because the mites are enclosed, spraying insecticides is ineffective. For more information on these galls, I’ve written a blogpost, which can be found at https://growingtogetherwithdonkinzler.wordpress.com/2017/06/08/whats-causing-the-bumps-on-area-maple-leaves/.
If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at email@example.com or call 701-241-5707. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.