Beets deserve a place in your garden both for their easy growth requirements and their versatility -- both the roots and the greens can be eaten. Knowing what problems beet leaves encounter while growing, makes it easier to begin treating them right away, before they suffer extensive damage.
Leafminer larvae are the legless maggots of flies. They're .03 inch long, when they first hatch, and grow to be about .3 inch long. Newly hatched white larvae turn lime green as they feed on leaves. Symptoms of leafminer damage include the appearance of light green or white mines that the larvae form when they burrow into leaves. The mines grow larger as they feed and may merge to form brown blotches. Control leafminers by destroying alternate leafminer weed hosts, and applying foliar insecticides, if necessary.
Aphids are small insects that destroy beet leaves by sucking plant juices out of them. These pear-shaped insects grow to be about 1/10 inch long and have long antennae. They're different colors, depending on the species, including green, pink, white, yellow, brown, black or gray. Aphids can be found on the bottom sides of leaves where they gather in large numbers. Control them by spraying a strong stream of water on the plants. Insecticidal soaps and horticultural oils are also effective.
Blister beetles are large, dark-colored beetles with thin white lines on their wingcovers. Garden springtails are tiny purple insects with yellow spots. They chew holes in the leaves of seedlings. Since these insects are just an occasional problem, control isn't usually necessary.
In addition to bacterial leafspot, several fungal leaf-spot diseases attack beets, including cercospora, ramularia and alternaria. Spots vary in color, depending on the infection and may be gray or brown with reddish-brown or black borders. Some leafspots cause a bluish-purple fuzz or dark fuzzy spore growth to appear. Leafspots can merge and form blotches. Other symptoms include the appearance of tiny black or white dots in the centers of the spots. Most leafspots care controlled by applying fungicides. Burying dead plant parts, and rotating crops, helps reduce infections of Cercospora fungus.
Beets are susceptible to several virus diseases. Aphids spread beet mosaic, which causes mottling in young leaves. The savoy virus is spread by the lacewing bug and causes leaves to curl and roll downward. Leaf veins swell and thicken and the tissue between the veins bulges. Dark rings develop in the rings and growth is reduced. Symptoms of virus yellows only appear in older leaves, which turn greenish yellow, especially at the tips. Leaves become thick and brittle and growth of the root is reduced. There are no ways to control viral diseases in beets.
- Ohio State University Extension; Growing Beets In The Home Garden; Pamela J. Bennett
- North Dakota State University Extension; Leafminers in Sugarbeets; Mark Boetel; July 2005
- Connecticut Agricultural Expermental Station: Beets
- Connecticut Agricultural Experiment Station; Aphids; Kimberly Stoner; June 2007
- Science in Farming Library; Plant Diseases -- Growing Sugar Beets
- North Dakota State University; Cercospora Leafspot of Sugarbeet; H.A. Lamey, et. al.; January 1996
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