Garden Pest and Plant Disease Listing - RO

ROOT-KNOT NEMATODE: Any nematode that causes swollen growths on plant roots. See Nematode for more information.

ROOT ROT: A name used to describe a disease caused by soil-borne fungi that kill plant roots. These fungi flourish in overly wet or poorly drained soil with insufficient aeration. The affected plants turn yellow, individual branches wilt or die, and the entire plant may die. There are very few fungicides that help. The best control is to improve drainage and cut back on watering.

ROOT WEEVILS: These insects attack both the foliage and roots of many plants. The adult beetles chew notches in the leaves. The larvae devour the roots, causing the plants to wilt or die. Control with floating row covers, hand-picking, sticky barriers on trunks, parasitic nematodes, pyrethrum, rotenone, or traditional pesticides.

ROSE CHAFER: A scarab beetle that damages many plants, including roses and other flowers, lawns, and vegetables. The damage is similar to that done by the Japanese beetle. Lacy patches appear on the leaves and deformed blossoms. To control, cultivate around the plants to destroy overwintering grubs; release parasitic nematodes, use row covers, or spray with rotenone, pyrethrum, or traditional insecticides.

ROTENONE: A broad-spectrum botanical insecticide derived from several tropical plants. One of the stronger and longer lasting botanicals. Also fairly toxic, especially to fish.

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