Organic Pest Control

by Doug
(in the garden)

There are a ton of ways to reduce insect problems in the home garden that don’t rely on chemicals. From companion planting (although the real research is a bit thin on this subject) to trap-cropping and rotation, we can do a lot of things to reduce insect problems.

But sooner or later we’re going to run into a problem. And that’s what this short post is about. These are the simple, easy to find, organic controls that gardeners can reach for in an emergency. It isn’t a handbook for total insect control in every situation; you still need to know what to use and what you’re trying to control. This is your first roadmap on the road to figuring out those emergency controls.

My first bit of advice

Never use any pest control product without reading the label.

I know, I know - you get the same advice from everybody but all you want to do is wipe out whatever’s eating your lettuce. Right. Me too.

But I’ve had folks write and ask why this fungicide wouldn’t kill whatever was eating the lettuce. And when I pointed out that it was an insect that was eating the lettuce not a fungus, they had problems understanding that just putting “something” on the plant wouldn’t fix it. Or worse, they put things that were intended for non-food pests onto a food crop.

More than once, I’ve had to tell readers not to use a systemic poison such as Cygon 2E on a food crop. Yes, it would kill the insect but then you’d be eating the leaves that were poisoned with something that could really kill you. I note that accidents such as this have happened in our food chain in the past and people have become very ill)

** So know what you want to control and read the label to make sure you’re using the right product.

Rules of thumb

Damage that happens at night and you can’t see any pest is often a slug. Look for slime trails on the tender leaves. Tomatoes eaten away in the middle from a small entrance hole is slug.

Black “soot” on leaves or fruit is often aphids. You should be able to see a small pear-shaped pest on tender growing tips.

Odd small holes here and there are often flea-beetles. These guys are really tough to see because they’re tiny and jump very quickly at the first sign of leaf movement (like you trying to see them).

Big holes on cabbage and broccoli crops are usually a green worm - the larvae of the cabbage butterfly.

Clouds of small white flying insects when you move leaves are whitefly.

Tomato plants that are disappearing before your eyes or overnight are (being eaten by) tomato hornworm. If you’re really quiet, you can hear the clicking of their eating. Squash them.

Squash leaves that disappear are normally squash bugs.

A Good Collection of Organic Controls

There are a few organic controls that form the backbone for almost all the major pests.

Water Jet

The first is a jet of water from a hose. You’ll be amazed at how quickly a jet of water knocks aphids and other crawling insects off a plant. No fuss, no muss, no residue, no mixing, no spraying and no aphids left. When they’re knocked off the plant, they are helpless food for the larger beetles and other predators living at ground level.


Insecticidal soap.

This is a fast knockdown product for many soft-bodies insects you can see. Remember that you have to hit them with the soap to kill ‘em. If you can’t see them, you can’t hit them and can’t kill them. There is no residual power in the soap and once it is dry, it is pretty much done.

It has to be repeated regularly (read the label) and mixed properly so it won’t burn the plants. It does tend to do interesting things to the colour of some blooms so do check to make sure what it can be used on.


Rotenone

Another fast knockdown product. This can a lethal product for mammals as well as insects so do wear protective clothing when using it. It only has a life span of 24 hours in sunlight and degrades naturally and quickly in the soil. You don’t have to see the insects to kill them but it helps to understand what you’re trying to control because it won’t work on everything in the garden; please read the label on this before you use it.

Diatomaceous Earth

Great stuff for crawling insects that you can’t see. Registered for a wide variety of pests and able to work for long periods of time. This is very fine powder, the remnants of long-dead sea creatures. While the powder feels like talcum powder to us, to small insects it is composed of microscopically sharp shards. It would be like walking over broken glass to us. Insects are pierced by the shards and dehydrate. Safe for animals, pets and humans.

Neem

The jury is still out on this product. You’ll see it used in many countries for insect control , it is registered in the U.S.

In Canada it is sold as a leaf-cleaning product and can’t be advertised or recommended in any other way.

Iron Phosphate

This organic product is use in slug controls and is perfectly harmless to pets. Works like magic. Keep the beer to yourself from now on.


Bt (Bacillus thuringiensis) is a bacteria that paralyzes the stomach of caterpillar-type pests. They eat the bacteria, essentially get a stomach ache, stop eating and crawl away and die. They do not die immediately but they pretty much stop eating fairly quickly. This product is available in the U.S.

While registered in Canada for some insects, it can be difficult to find at garden shops. The bacteria is alive so it has a relatively short life span and while it is available for commercial use, there are no Canadian sources for consumers at the time of printing. 

So in short - those are the only natural insect control products you're likely to ever need in your garden. Toss in a bit of sticky horticultural glue and you're all set.