Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SUNDAY, February 28, 1993 TAG: 9303010342
SECTION: HOMES PAGE: E1 EDITION: METRO
SOURCE: John Arbogast
DATELINE: LENGTH: Medium
WOOLLY APHID EGGS WAITING PATIENTLY FOR SPRING
Many folks recently have asked about the small, cottony, whitish puffballs they have found in midwinter on branches of hemlocks along the base of needles. These are the eggs and wooly covering of the hemlock woolly adelgid, also called hemlock woolly aphid.The eggs will hatch in mid- to late spring into small insects that will suck sap from the branches of hemlocks. This pest has been difficult to control.
If nothing is done once the eggs are found, the hemlock may be killed within a year or two. The insect lab at Virginia Tech has suggested an application of horticulture oil, which will physically smother the hemlock woolly aphid in whatever stage it is in.
A 2 percent solution of the oil can be applied to infested hemlocks October to April while the tree is not actively growing, or a 1 percent solution from May through September. Complete coverage of the hemlock can result in total elimination of the adelgids.
Only one complete application is necessary. The oil may discolor the hemlock foliage for one season.
Persons who have called about this problem have heard us quote from Tech's Pest Management Guide statement that only diazinon is legally approved for control of the adelgid.
Q: I have three semi-dwarf apple trees - golden delicious, red delicious and winesap - planted in the back of my yard. The first and second times that they produced, the apples were great on the golden and red delicious trees. The winesap doesn't produce at all, but I'm not concerned about that. Over the last four or five years, if the blossoms don't come out too early and get frozen by bad weather, the apples on the red delicious get a lot of "corking" and the golden delicious seems to have a lot of black fungus on the outside. I spray early and keep spraying with Dragon Fruit Spray during the season, but the spray doesn't do any good whatsoever for these problems. To help you to diagnose the problem, let me tell you what there is growing nearby; along the border of my property on my neighbor's property is a line of pine trees and not too far away on my property is an ornamental crab apple tree. Please let me know what I should do to clear up this problem. R.W.J., Vinton
A: "Corking" or "cork spot" (clusters of dead cells that usually are tan to brown within the fleshy part of the apple) is caused by a deficiency of calcium and boron in the fruit, which can be caused by stressful conditions such as unfavorable spring or summer weather and/or poor quality soil. Also, an apple tree that is in poor vigor may be more prone to corking.
This problem varies among the different apple varieties; some are more prone than others.
Sprays of calcium and/or boron have been used to combat the problem. Calcium chloride should not be mixed with soluble boron. However, don't rely on one practice - like sprays - to correct the problem. Take a soil test now. Soil pH should be in the optimum range of 6.0 to 6.5 to make sure that calcium as well as all other nutrients are available for the trees.
Observe the amount of new-shoot growth that each apple tree makes in the spring. This is a good indicator of tree vigor and should not be more than 20 inches for bearing trees. If the amount of new growth is more than that, nitrogen fertilization applied directly to the tree or indirectly applied through turf fertilizer nearby should be reduced, and heavy apple pruning should not be done.
The black fungus on the skin of the golden delicious apples sounds like the infection called "sooty blotch of apples." This fungus loves high humidity and can be a problem in late summer.
I don't have a label of the fruit spray you used, but I would think that it should have controlled sooty blotch. The key is to maintain fungicide protection of the fruit up to within about four weeks of harvest, as long as that is permitted by the label of the fungicide being used.
Q: I have English ivy taking over everything in my back yard. What can I buy to kill it? I have tried several things. L.K.M., Roanoke
A: There may not be anything you can apply to control the ivy. Physical removal is probably your only safe choice, either by digging or clipping. Glyphosate, which is sold as Roundup and Kleenup, is suggested by Virginia Tech for use on actively growing unwanted plants. However, I recall applying Roundup on English ivy that came into my yard with a tree transplanted from another landscape, and the ivy did not die.
Check garden centers and nurseries for any control products they might have, but please be sure to read the label before using because some plant killers might move to adjacent areas and cause loss of other plants.
Got a question about your lawn, garden, plants, or insects? Write to Dear John, c/o the Roanoke Times & World-News, P.O. Box 2491, Roanoke
John Arbogast is the agriculture extension agent for Roanoke