The Basics of Organic Pest Control

by Doug
(in his garden)

The basics of Organic Pest Control


The first thing to understand is that western gardeners have an easier time of this than eastern gardeners. The western gardener has varieties available that are resistant to certain kinds of common orchard pests while the eastern grower is without those choices (at this time)

So we're talking about two distinct gardening zones and you can pretty much differentiate it based on the amount of rainfall the area gets. Areas of high rainfall and mixed forests in the Northeast (eastern half of the continent) have higher insect and disease problems than areas of the west that are drier. The amount of water available is the key determining factor. (The possible exception are parts of California which comes close to eastern concerns) I also note that western resources from extension / ag offices are more numerous for organic gardeners (even if you have to use commercial manuals) than in the east.

There are several pests that create major problems for growers in the east but none as bad as the plum curculio. This bit of nastiness is hard to control because it's not the adult that's the problem but the egg/larva that are laid in the apples and then develop/ruin the fruit. And not much stops adults overwintering in leaf litter. Rodale Research Institute went at this insect full out in the 1990's and found, even by using all available techniques, they could only control 50% of the pests.

However, in the early 2000's a product made from Kaolin (fine clay particles) has appeared on the market. This product
Surround^® at Home^® Crop Protectant covers the emerging fruit (you have to apply it as per directions on the label to maintain coverage and control) and prevents insects and some diseases from establishing themselves. (The clay gets on the insects and they leave or they don't want to eat through the clay - also the white covering masks the visual signs of a target food) It is washable - and as long as you wash your fruit before you eat it (who wants to eat clay?) then you're getting an environmentally safe system that seems to work on leafrollers and leafhoppers; suppression of mites, codling moth, PC, stink bugs, apple maggot, and thrips. It reduces heat stress, fruit drop and sunburn; providing greater return bloom; and improved color in some varieties. With Surround, you're not killing pests - you're simply preventing them from eating your produce. What is important is that you follow application directions to the letter re timing and these will be on the label.

Sticky Traps

Some gardeners use sticky horticultural glue on trapping mechanisms. Some take a large red ball (the size of an apple) and coat it with this glue. The glue doesn't dry but does trap insects who believe they've found a ripe apple to eat. These balls wind up quite covered in pests over a fairly short time.

Economy Red Sphere Traps

A second system is to wrap masking tape around the trunk of a tree slightly above pet or small child level. Make sure there are no openings under the tape in bark cracks (stuff these with cotton or other soft material) The coat the masking tape with the same glue. Any pest such as caterpillars that spend part of their time out of the tree can't climb back into the tree and it's not unusual to see hordes of caterpillars at the base of trees (they can be sprayed with soap there)

Soap sprays and other organic sprays are not overly useful as many of them are contact sprays (they have to hit the pest to kill it) plus some of these pests are not overly susceptible to soap sprays. Plus the size of a tree means getting the spray into the foliage (and under it) is difficult with home-scale equipment.

Messenger or Harpin

Researchers have also discovered that when plants are "attacked" by something that arouses their defense mechanisms, they become resistant to a wider range of other problems. It's the same mechanism as inoculating people with a small dose of a disease (measles vaccine) so the body develops resistance to that disease. In the case of plants, inoculating them with a chemical called Harpin (a chemical released when plants were infected with fireblight) didn't cause fireblight but was a chemical signal to increase resistance. When Harpin (sold under names such as Messenger is sprayed onto plant leaves, the plant responds by become more resistant to a wide range of problems. This can be used on a wide range of plants with problems and not just fruit trees. See the label for application directions and plant effects.

Horticultural Oils

Hort oils (light oils) have been used quite extensively in dormant oil sprays but are now being used in preventative and knock-down sprays as well. Powdery mildew can be controlled by this kind of product
Oil-Away^TM Supreme Insecticidal Oil

I also note that Palmolive Dish Detergent can control powdery mildew on tree fruit but that it can also rather quickly burn or deform fruit so you have to be very careful about this. The linked article outlines concerns and amounts (it's part of the research/advanced gardening series).