These tips are from yet another email, and the information is so useful that I thought that I should post it:
ORGANIC TIPS – Getting rid of the troublemakers is one way to help rid diseases; especially if you want to grow organically! Remove varieties susceptible to diseases and you will remove the source of infections and overall disease problems.
PARASITIC NEMATODES are microscopic eel-like worms that naturally occur in soil. They can be purchased to reduce levels of many insects. Some varieties are insect specific thereby reducing harm to non target insects.
PHEROMONE TRAPS use specific (sex hormones) attractants to lure insects to where they they are trapped. They also monitor when insects appear on the scene. Sticky cards are a great help for insects such as whitefly (yellow) and midges (blue cards).
PYRETHRINS kills many soft-bodied and some hard-bodied insects and causes most flying insects to ‘drop’ almost immediately upon exposure. It is also highly irritating to other insects and is utilized as a pest dispersion agent. Pyrethrins have a low level of toxicity, and are among the few insecticides that are cleared by the EPA for use around food handling and preparation areas. However, it is not harmless; mix, apply, and dispose as carefully as you would any other pesticide. Pyrethrins rapidly degrade when exposed to light or moisture, so do not persist for long in the environment. Some pyrethrin-based products are combined with more toxic pesticides.
ROTONONE [update: Rotonone is linked to causing parkinson disease and is therefore not recommended]. Rotonone acts as a stomach poison and as a contact insecticide. Not toxic to honeybees, but will kill some beneficial insects. Registered for use against most chewing insects on many vegetables and some fruits. Different brands and formulas are available for various pests. Both liquid and dust are available commercially. It has been fatal to mammals if inhaled over extended periods. Rotenone is effective against a wide range of insects and has a short residual life.
RYANIA is a stomach poison, which will cause an insect to undergo a long period of inactivity before its death. Its residual period is longer than other botanicals. Ryania is moderate in acute or chronic oral toxicity in mammals, this is why more attention has been given to this insecticide in recent years.
SABADILLA can be applied up to one day before crop harvest. It is effective against the true bugs, leaf feeding caterpillars, Mexican bean beetles and thrips. Sabadilla dust is considered among the least toxic of the various botanicals, however, be sure to follow all precautions listed on the product labels.
SOIL SOLARIZATION – Uses plastic to solarize the soil. It may destroy the soil structure but, can be beneficial. It is very useful in weed control and for clearing an area of vegetation without the use of herbicides. The beneficial soil organisms can take more heat versus the harmful soil pathogens allowing them to make a speedy return after solarizing an area. The plastic concentrates the sun’s energy which heats the soil to a very high degree, sterilizing it. Thus killing off soil pests, disease and weed seeds. Depending on the climate solarization has been shown to control certain wilts, crown gall diseases, nematodes, grassy weeds and weed seeds. Nematodes have the ability to survive higher soil temperatures. The deeper the heat penetrates the soil the better the results ie. with optimum conditions disease & weed control can last up to three years.
Soil Solarization Technique:
Best done during the heat of the summer. Till the soil to a depth of at least 8 inches. Rake out all debris, smooth the area as level as possible. Then soak the soil to a depth of 18 inches. Make a slight depression at the boundary of the bed. Stretch some clear 4 mil plastic over the bed as tightly as you can, adhering it to the soil. Use rocks, more soil, landscape pins, etc to secure it snuggly in place. Now; let it cook for at least 4 weeks (cooler zones allow 6 to 8 weeks). Remove the plastic, and till the soil lightly before planting.
In more northern climates add manure prior to putting down the plastic to speed up the process by increasing soil temp as the manure decomposes. This also increases the level of gaseous ammonia in the soil, thus giving the process an extra kick! Use two layers of plastic to create more of an insulating effect by trapping more heat. Incorporate shredded vegetables from the cruciferous family (broccoli stems, cabbage trimmings etc). These vegetables may have an effect in ridding the soil of blights. Let the trimmings dry out in the sun until brittle, mix them into the top 6 inches of soil, proceed with the process.
SULFUR is effective on flowers, fruits, and vegetables in preventing powdery mildew, rust, and black spot. It can also control mites and several insect pests. It is toxic to a few plants, including cucumber, raspberry, and apricot, so check the label carefully. Keep in mind that sulfur is sometimes combined with other pesticides (which have higher toxicity levels). Lime sulfur (calcium polysulfide) is effective against the diseases and pests noted above and can be used in combination with horticultural oil (as dormant spray).
SYRPHID FLIES have abdominal stripes like wasps and bees but have not sting. The stripes protect them against would be predators. Many species of Syrphid Flies are pollinators, second only to bees. They are distinguished from bees by their ability to hoover like little helicopters. Syrphid or hoover fly larvae feed exclusively on aphids. Syrphids lay most of their eggs on plants that are heavily infested with aphid colonies. They lay between 400 to 1000 oblong white eggs which hatch within days. One larvae can consume 200-800 aphids in its 7 to 10 day life. Syrphids produce many generations a year and are considered a very effective predator of aphids.