NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665

August 27, 1998

Hortiscope

Ron Smith, Extension Horticulturist
North Dakota State University

Q: Enclosed are a couple of leaves from my dogwood shrub. Can you tell me what is eating them, and what to do to stop it? Also, if I prune my raspberries this fall, will they bear fruit next year? (Valley City, N.D.)

A: The damage appears to be that of a "garden variety" caterpillar that visited your dogwoods for a snack and are now beautiful butterflies!

I suggest no sprays at this time; next spring before leaf-out apply dormant oil to the shrubs to kill off any eggs the butterflies may have laid.

Raspberries bloom on second year wood (except the fall bloomers), so the canes that grew this summer should bear fruit next summer. Old canes that bare fruit this year should be pruned out completely.

Q: Why are my asters turning yellow and starting to dry up right before they bloom? (Miller, S.D.)

A: Well, there are aster yellows, rust, and powdery mildew that beset these beautiful plants. My guess from your description is that it is likely serving as the alternate host to pine-needle rust. If you or your immediate neighbors have pine trees, they are likely being afflicted with this disease and passing it back to the asters you plant.

My suggestion; try a different annual—there are plenty out there!

Q: When is the best time of year to thin out spruce trees? (Wing, N.D.)

A: Early fall or late summer is the best time. The soil is warm for root regrowth and the days cooler for less transpirational stress. If you choose to plant in the spring, get it done before the new growth starts. Either time, be sure to supply adequate water at the time of transplanting.

Q: Enclosed is a sample of a weed that seems to be taking over the neighborhood. Can you tell me what kind of weed it is and tell me how to control it? (Fargo, N.D.)

A: This is a good sample of yellow foxtail. It is an annual weed that is easily controlled with pre-emergent herbicides like Dacthal, Betasan, pendimethalin, or Tupersan.

Apply one of these next spring as the lilacs in your area are starting to bloom.

Q: Can you identify this plant for me? It is growing in my garden. (Ypsilanti, N.D.)

A: A good specimen of crabgrass! Be happy you pulled it out—and do likewise with the others like it!

Q: Can you tell me what is wrong with this tree? It seems to be losing its leaves. (Harvey, N.D.)

A: The tree leaves are from what appears to be a Redmond linden. The plant is suffering from a disease known as leaf blight (Cercospora microsora). Control by gathering and destroying fallen leaves. Next spring, prior to leaf-opening, spray with lime-sulfur.

Apply Benlate after leaves fully open, but before the spotting on the foliage develops.

Q: Can you tell my what kind of tree this leaf is from? (Fargo, N.D.)

A: The leaf appears to have come from a hackberry, Celtis occidentalis.

Q: Will fertilizer spikes last over the winter? (Garrison, N.D.)

A: I know of no reason why the spikes shouldn't keep for another year, as long as they are kept dry.

Q: Last year I planted some peach seeds and some cherry seeds. When my husband worked up the garden this year, the peach seedlings and some other seedlings emerged. Can you confirm that one of these is a peach leaf and that one of the others is a cherry leaf, and what we can expect from these two trees? (Montpelier, N.D.)

A: You indeed have peach trees growing—nice going! Now, the trick is two fold: 1. Keep the deer from finding them, and 2. keep them from freezing out! The other leaves were not from a cherry but from an ash.

To try to get the peach to survive, I suggest growing it as a shrub so you can cover it going into the winter (like roses!). Good luck and keep me posted!

Q: Can you tell me what kind of plant I have enclosed a leaf from? In 1997 it had beautiful blue flowers, but this year the top of the plant turned a silver color and dried up. (Sykeston, N.D.)

A: The leaf sample that was whole looked like it came from a delphinium. They generally do OK as long as the weather doesn't get too hot. The diseased material strongly resembled a combination of mildew and botrytis blight—the result of too much water, humidity and temperatures too high.

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Source: Ron Smith (701) 231-8161

Editor: Dean Hulse (701) 231-6136