This is our first time for vegetable gardening in BC. The garden is growing very well. We have mastered the slugs and snails, but now our lettuce and green onions have been attacked by a small brown worm in the root. We are losing many plants daily. We picked out 20 worms by hand yesterday. Help! Any other suggestions would be very helpful.
Could be wireworms in the soil. If it is it can be tough to eradicate and even just to control them. Try broad spectrum insecticides as a soil drench in the affected area and hope for the best. For a more positive ID, wireworms are about 1 to 2 cm long, very thin, hard and rigid to the touch, orange-ish colored and they tend to writhe around when you try to play with them. ;o)
With respect to the application of "broad spectrum insecticides"; while this might have the desired effect of killing off the wireworms, it would also kill off most other invertebrates in the soil. Such advice is counter-productive. Most "pests" are actually better adapted to surviving adverse conditions (such as pesticide applications) than most other invertebrates. This is what makes them pests. The natural predators, competitors, antagonists and parasites are often knocked back more severely and return more slowly. Another consequence of pesticide applications is the emergence of secondary pests, whose effects are relatively minor until the target pest is removed. Without competition, these pests then become major pests. An established, diversified landscape that has a variety of habitats and microhabitats, which encourage the widest range of competitors, antagonists, predators and parasites is a much better approach to pest control (and much safer for the environment). Such ecologically sustainable landscapes are possible when following an integrated pest management approach. The following is a good working definition of IPM: As stated in the California Healthy Schools Act of 2000 (Assembly Bill 2260) "…a pest management strategy that focuses on long-term prevention or suppression of pest problems through a combination of techniques such as monitoring for pest presence and establishing treatment threshold levels, using non-chemical practices to make the habitat less conducive to pest development, improving sanitation, and employing mechanical and physical controls. Pesticides that pose the least possible hazard and are effective in a manner that minimizes risks to people, property, and the environment, are used only after careful monitoring indicates they are needed according to pre-established guidelines and treatment thresholds." To use the wireworm example, we know that wireworm are common in gardens that have been recently converted from grass or pasture. This is because wireworms are common inhabitants of turf and feed on the undecomposed plant residues. Reducing these residues will significantly reduce the presence of wireworms. Tilling the soil to increase oxygen diffusion will hasten the decomposition process. Birds are common predators, but may not visit (or could be poisoned) after pesticide application. After a few years, wireworm populations will naturally subside because the adults (click beetles) lay eggs preferentially in turf, not in open soil. Wireworm can be trapped-out by baiting. A bait station consists of a coffee can sized hole in the soil. A small pile of corn and grain is left on the bottom, and a layer of loose soil is piled on top. The hole is then covered with plastic to encourage the formation of gases, which attract the wireworms. The bait station is then checked periodically and the wireworms picked out and destroyed. Bait stations are often used to monitor the severity of an infestation, but at higher densities, stations can trap-out significant numbers of insects. Good luck!
Wireworms can also be baited with pieces of potato stuck on a stick and buried 2 -3 inches below the ground. Every two days pull up the stick and pick off the wireworms that are burrowing in to the potato. A potato will last about a week. We pick off about 25 of the little critters every two days and drown them in soapy water. Works for us.
