In the Garden:
Southern California Coastal & Inland Valleys
November, 2009
Regional Report

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Beautiful Romanesco "broccoflower" is a combination of broccoli and cauliflower, and tastes milder and sweeter than broccoli.

The (Almost) Last Pests: Nematodes, Sowbugs and Pillbugs, Thrips

Nematodes are particularly nasty for many garden plants, but incorporating lots of good old organic matter will help. Sowbugs and pillbugs -- favorite playthings when I was a child -- are more vilified (along with earwigs) than they deserve, since they thrive on dead plant matter. Thrips are so minute you can see only their telltale signs.

Nematodes
PROBLEM: The extended family of pest nematodes causes damage to plants that results in the foliage becoming yellowish and wilting readily on hot days, and roots that are stunted, knobby, and distorted with galls. Potato and sweet potato tubers have irregular dark brown sunken areas.
SOLUTION: Plant resistant varieties. Incorporate organic matter. Rotate crops. Grow non-host plants for three or four years, and incorporate the plant matter into the soil before replanting host plants. Nematodes are susceptible to drying out, so turning the soil and allowing it to dry thoroughly can help reduce populations. Infested plant root systems should be carefully destroyed, not mulched or composted. Nematodes will not be a problem in biologically active soil, as the bacteria eat the nematode eggs. Nematode damage develops more frequently on stressed plants where the root systems are unable to take up adequate water and nutrients. Vegetables which are relatively resistant to root-knot nematode are asparagus, the cole crops, and sweet corn. Cherry tomatoes do not seem to be affected as severely as other tomatoes, and they will produce well, even in moderately infested soil. Increasingly numerous nematode-resistant varieties of susceptible vegetables are available to choose from, especially of tomatoes. Plant red salvia, dahlia, calendula, and African and French marigolds as repellents.

Sowbugs and Pillbugs
PROBLEM: Sowbugs and pillbugs are generally present in the garden, eating decayed vegetation.
SOLUTION: Keep soil surface free of much for a two-inch area around the plant stems. Provide good air circulation between plant foliage and the mulch underneath. Remove lower decayed plant leaves from the surface of the soil or mulch.

Thrips
PROBLEM: When dwarfed foliage wilts, is speckled, curled, crinkled and papery, silvery or tan colored, and dies, suspect thrips. Onions develop whitish chainlike marks on leaf surfaces and on distorted bulbs. Thrips thrive in hot, dry weather.
SOLUTION: Wash or soak seeds in a saltwater solution before planting them. Plant seeds as early as possible so that the plants are mature enough to withstand the initial infestation period in spring. Unless the infestation is very heavy, plants will outgrow the problem. Dust with diatomaceous earth or spray with solutions of soap or oil. Rotate crops in three-year cycles. Maintain sufficient moisture. Keep garden free of weeds. Employ lacewings, ladybugs, and predatory wasps. As with aphids, foil or white plastic mulch disorients thrips, and they'll settle elsewhere to feed.


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