Insects and Diseases

The best way to control pests and diseases is to build a healthy garden environment.  Keep your plants healthy with a good fertility program, adequate water, few weeds, and soil with good drainage.  Plants that are stressed are more likely to have problems.

Rotate your crops.  Moving your crops around confuses bugs that favor particular vegetables.

Also, intersperse your garden with companion plants that are known to repel pests.   Herbs, garlic and marigolds can be beneficial.

If you do have problems, it may be that the damage is minimal and you can live with it, or the damage may be ornamental only.  Doing nothing is an option.   To routinely run for a can of spray when you see a problem is not in the best interest of your garden ecosystem.   There are many bugs that do no damage to crops, and may in fact be beneficial.

A book that I find very useful for identifying plant pests is: The Organic Gardener’s Handbook of Natural Pest and Disease Control: A Complete Guide to Maintaining a Healthy Garden and Yard the Earth-Friendly Way (Rodale Organic Gardening Books)

 From Texas A&M University – Insects

For wonderful photos of bugs, Here is a webpage that is a wonderful insect identification guide.

 From Cornell University – Diseases

Here is a page from their website with vegetable diseases list by crop.   The fact sheets have good photos.

Materials can be used to control pests.  Two insect control solutions I like are silver mulch and lightweight row cover.  They create an environment that is unfriendly to pests.

Silver mulch confuses insects by reflecting light.  This causes them to be less likely to land on your plants.  The film will disorients and repel aphids, flea beetles, white files and thrips. The shiny surface also discourages crawling pests like snails and slugs.  This mulch also offers weed and temperature control.  And it reflects light onto the undersides of plants thereby increasing photosynthesis leading to more rapid growth.

Lightweight Row Cover – We use this row cover to control flea beetles and cabbage worms.  It can protect your plants from squash bugs, cucumber beetles, squash vine borers and root maggots.  It will help keep the rabbits and deer away.  It can also be used for pollination control.  It provides some protection from damaging winds.

If you do feel that an insecticide is necessary, there are organic options.

Many organic insecticides come from plants or plant products.  Look for pyrethrum (not synthetic pyrethroids), rotenone, neem, garlic/hot pepper sprays, and insecticidal soaps.

Pyrethrum or pyrethrins come from African chrysanthemums, and control aphids, white flies, stinkbugs and mites. Neem comes from the seeds and leaves of the neem tree and acts as a insect repellent. Neem is nontoxic to animals and humans and beneficial to bees.

Consider adding beneficial insects to your ecosystem.  Large garden centers have them available, or below are links to the products on Amazon.

  • Ladybugs are general predators that feed on a variety of slow-moving insects including Aphids, Moth eggs, Mites, Scales, Thrips, Leaf Hoppers, Mealybugs, Chinch Bugs, Asparagus Beetle larvae, Whitefly and others
  • The praying mantis is a general predator of many insects.

  • Lacewings eat aphids, caterpillars, small beetles, scale insects, leafhoppers, thrips, small flies, and other small insects and eggs.

For fungal and bacterial problems, organic growers have the options of copper and sulfer compounds.

A general use product we keep on hand is Organocide.  It is an insecticide and fungicide for organic crop protection.  It kills 25 problem insects including spider mites, aphids, thrips, whiteflies, mealybugs and scale insects.  It controls major diseases including powdery mildew and blackspot.  Dilute 2 oz. of Organocide per gallon of water and keep agitated.  Use a sprayer that will put out a fine spray.  Cover plants with this spray.

Another product we use is Bt (bacillus thuringiensis).  It affects certain types of insects and is most commonly used for the larval stage of moths.  We used this product for cabbage worms.  There’s nothing worse than finding one of these critters on your dinner plate.  Even with a dollop of cheese sauce, my kids now refuse to eat their broccoli.

Bt doesn’t affect bees or many other beneficial insects.  Bt has several trade names.    Safer Garden Dust contains Bt, and controls many garden insect pests including cabbage worms, tomato hornworms, loopers, cutworms, and other caterpillars.  This product is approved by OMRI for organic use.  Thorough leaf coverage is necessary for effective control.  After ingesting a treated portion of the leaf, caterpillars stop feeding within a few hours.  Death occurs within a few days.