Small spots and a black coat invade a stand of English ivy

BACKYARD Q&A

March 04, 2001

Q. I have quite a bit of English ivy under some trees in my yard that seems to be diseased. There are small round spots on many of the leaves. Others look like they are thinly coated with black tar. I never noticed this before. Is there anything I can do?

A. You have two separate problems, neither of which is life-threatening to a healthy stand of English ivy. The spots are caused by bacterial leaf-spot disease. The disease causes more noticeable injury during wet, humid summers. Prune out and discard the badly infected leaves and stems. If the infection is severe, you can spray a copper or copper-sulfate fungicide during the spring and summer. The tar-like coating is sooty mold. Affected leaves can also be pruned and discarded.

Q. I have had a problem with crabgrass in my vegetable beds for the past few years. I try to be organic but wonder if it would be best to kill it once and for all with an herbicide. What do you think about using Roundup?

A. You'll probably have cool season greens growing in your garden when the crabgrass seeds begin sprouting in early to mid-April. Spraying Roundup then may injure those crops. Furthermore, after a Roundup application, one must wait three days before sowing seed directly into the ground and 30 days before transplanting vegetables. A single application may not be very effective because new crabgrass seed will germinate each time you turn or cultivate the soil. Your best bet is to remove the crabgrass by hand and apply a thick organic mulch to control it through the season. And, of course, don't allow any crabgrass plants to reach maturity and spread new seed.

Q. I have some large bamboo in my backyard and noticed that there is a fair amount of fine sawdust inside some of the stalks. I also see little holes drilled into the woody cross- sections that separate each section of the stalk. What's going on? Do I have a hidden termite problem?

A. You're seeing signs of the powder post beetle, a common wood-infesting pest. The adults make the small round holes, usually in younger, more succulent culms (stalks). The larvae cannot digest cellulose; they survive on the sugars in young plant tissue. You may be seeing signs of old damage. These beetles are not a threat to your home.

THIS WEEK'S CHECKLIST

1. Sow lettuce, spinach, radishes and other fast-growing salad greens in fertile soil. Keep the young plants watered well and fertilize with a balanced soluble fertilizer. Cover the bed with a floating row cover to protect the plants and promote early growth.

2. Clean out nest boxes for songbirds or install new ones.

Backyard Q&A is by Jon Traunfeld, regional specialist for the Home and Garden Information Center, Maryland Cooperative Extension Services of the University of Maryland. For additional information on these questions, or if you have questions of your own, call the center's hot line at 800-342-2507, or visit its Web site at www.agnr.umd.edu / users / hgic.

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