Water turns an ugly green in a new backyard pond


July 18, 1999

Q. My sister and I just finished building a beautiful pond in her back yard. The problem is, the water in the pond has turned a disgusting green. I can't even see the fish swimming and I'm afraid the algae will kill the plants I bought to put in the pond. What should I do?

A. Algae growth is rapid during warm weather, especially when there are no plants to cover the water surface. Put your plants in as soon as possible; the algae will not harm them. You'll notice the water becoming clearer within a few weeks.

The unicellular algae that is causing the water to turn green actually inhibits the growth of the more troublesome filamentous algae that covers water plants and clogs filters.

Q. We're being invaded by crawling black bugs with long snouts. I caught some of them today marching in under the front door. This is the first time this has ever happened. What are they after? Do I need an exterminator?

A. The extended drought has forced many outdoor creatures to seek food, water and protection indoors. Your guests are probably either strawberry root weevils or black vine weevils. They feed on many different plants outdoors and are simply a nuisance indoors. They will not damage or take over your home and you do not need an exterminator. Vacuum or sweep them up and use screening, caulking, door sweeps and other such measures to exclude them from your home.

Q. I have eight ancho chili pepper plants growing in containers on my deck. They are doing great except for one plant that has some discolored and deformed leaves. Is this likely to get worse? Is there any treatment?

A. Chilies are susceptible to many different viruses that are transmitted by sucking insect pests like aphids, leafhoppers and thrips. The viruses cannot spread from plant to plant without these insects. If you uncurl some of the deformed leaves you may find evidence of aphid feeding.

The symptoms you see could worsen, but it is just as likely that your plant will continue to grow and produce fruit. There is only one treatment for your problem: Control early-season pests with applications of insecticidal soap or horticultural oil.


1. Leave cicada killer wasps alone. You may notice them buzzing around your yard this time of year. They may look menacing, but they are completely harmless.

2. Remove and discard the various mushrooms and slime mold that grow in mulches during warm, wet weather.

3. Prune back errant azalea and rhododendron shoots to maintain an attractive plant shape.

Garden tips are provided by the Home and Garden Information Center of the Cooperative Extension Service 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.

Pub Date: 07/18/99

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