Controling Root Maggots
Probably the worst pest in an Alaskan garden is the turnip maggot, more commonly called the root maggot. The larvae feed on the roots of cabbage, radishes, turnips, rutabaga, cauliflower and broccoli. Brussels sprouts are seldom attacked by the maggots. Root maggots are generally prevalent every year, very widespread, and consistently a serious threat.
The maggots overwinter as pupae, emerge as adult flies in late May, mate and lay white eggs one-eighth inch long by one-sixteenth inch wide on the plant stem at or just below the soil surface. In two to three days, the eggs hatch and the maggots tunnel into the roots. Two to three weeks later the maggots become pupae (the resting stage), during which time they change to adult form. The cycle is then repeated. Those larvae which pupate after mid-July do not emerge until the following spring.
This means maggots are a constant threat for the entire growing season, and unless cultural practices are followed to keep populations at a low level, the chances of producing an edible crop are not good.
Organic methods to help control root maggots.
1. Plant all crops susceptible to root maggots as far from a previous year planting as possible.
2. As soon as crops are harvested, immediately destroy all plant residue to prevent maturation of any maggots that may be present.
3. Eliminate all weedy mustards, which serve as wild hosts.
Chemicals are widely used and are an effective method of control.
1. When planting seed, drench the soil along the row with a liquid solution of Diazinon as soon as the seedlings break the ground, per the manufacturer’s recommendations.
2. When transplanting seedlings water each plant with one cup of Diazinon solution. No treatment for maggot control is season-long. You must make an application every seven to ten days, soaking the soil with a Diazinon solution around the base of each plant.
Maggots are the only major insect problem for locally grown cole crops (avoiding imported pests). As the cole family - cabbage, Brussels sprouts, cauliflower and broccoli - get larger, the stems become tougher, making them more resistant to damage. In some cases varieties may be resistant to root maggots like the turnip variety Petrowski.
Since Diazinon has a short shelf life, do not store the chemical from one year to the next as the old chemical may not provide effective control.
Phone: (907) 344-0347
Office: 12101 Division Street, Anchorage, AK 99515
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