Root maggot at end of knife on radish.
Root maggot damage to cabbage. Plants suddenly wilt. This in spite of a chemical insecticide in soil.
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Over large areas of North America in early March the ground is frozen and snow may even be several feet deep. However, historically this will rapidly change within only a month.
Although the ground will be thawed, warm season vegetables like corn and tomatoes can be damaged by frost. Which vegetable can the eager gardener plant? Typically the first vegetables to plant are Cole crops like broccoli, cabbage, and cauliflower or root crops like radishes. Unfortunately, all these delicious vegetables are susceptible to serious damage by root maggots.
Root maggots develop from eggs laid by female flies near to the stalk of susceptible plants. The maggots hatch, them crawl too the plant and follow the stem down to the roots. The maggots feed extensively on roots and spread disease. With most of its roots destroyed the apparently healthy plant suddenly wilts as if through drought. Digging up the plant reveals the devastation underground and perhaps the maggots too.
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Root maggot at end of knife on radish. |
Root maggot damage to cabbage. Plants suddenly wilt. This in spite of a chemical insecticide in soil. |
Not only do chemical pesticides present health risks, but also often since they are subject to quick breakdown, they have limited effect. What other alternatives are there?
One alternative involves using row covers (fine mesh nets that let sunlight through) to prevent egg laying by flies. The covers must provide complete and tight coverage and are best intermittently supported by hoops or other frame.
Another alternative is to use beneficial nematodes. These are applied either on seedling plugs in trays, for cole vegetables or applied in seed furrows for radishes and other root vegetables. Good results have also been obtained applying nematodes to the soil surface around newly planted cole vegetables. For information on beneficial nematodes and ordering see http://www.biologicco.com/products/L&G scanmask.htm
Text copyright by Albert Pye, Ph.D., BioLogic Company http://www.biologicco.com/
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