Fungicide fights mildew on lilacs

Garden Q&A

September 21, 1997

I have two beautiful lilacs with leaves that are covered with a pale white powder. The garden-center people said it was powdery mildew and recommended I buy a rather expensive fungicide to control it. Will this disease hurt my trees, and what is the best treatment?

Powdery mildew, a common fungal disease, is usually seen on susceptible lilacs by the end of summer. It sounds as if your lilacs are severely infected, so treatment with a fungicide at this time and again in the spring during budbreak is warranted. We recommend ultra-fine horticultural oil as an effective and reasonably priced fungicide.

My brother-in-law in North Carolina says he plants garlic cloves from the supermarket in his garden in the fall and gets great crops of garlic the following summer. Will this work in Maryland?

Sure it will. Most supermarket garlic is the soft-neck type grown in California. It does not produce flowers. Break up a head of garlic into individual cloves and plant only the largest ones. They should be planted the last two weeks in October in rich garden soil.

Space the cloves 4 inches apart and your rows 12 inches apart. Plant the cloves with the pointed end up, cover with 1 to 2 inches of soil and mulch the bed with shredded leaves right after Thanksgiving.

Your garlic will be ready to harvest around the beginning of July.

There is a huge paper wasp nest hanging from a tree branch behind our house. We see lots of wasps going in and out, and we're worried about kids getting stung.

Will the nest be active next year? Should we destroy it now?

The large paper nests of the bald-faced hornet are spectacular by early autumn.

The hornets are beneficial insects that are harmless if left alone. They will become aggressive, however, if their nest is disturbed.

Leave the nest alone.

All of the occupants will die in the nest after a few hard freezes. The new queen will overwinter in protected areas and will start a new nest next year in a different location.

Garden tips are provided by the Home and Garden Information Center of the Cooperative Extension Service of the University of Maryland. For more 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 http: // www.agnr.umd.edu/hgic.

Checklist

* Start taking notes on the performance of the different flowers and vegetables you grew this summer. This will help you make informed decisions next year.

* Check plants for infestations of mealy bug, whitefly and other pests before bringing them indoors.

* Turn compost piles to hasten decomposition. Room must be made for the large amount of spent plants and leaves that soon will be placed in the piles.

Pub Date: 9/21/97

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