When it comes to pest control, many farmers reach for insecticides first. We had always thought there were different, possibly less toxic ways to combat pest issues. When I came across research done by a professor in the U.S., I was encouraged to research alternative methods of pest control on our farm. David Pimentel, professor of entomology at Cornell University, wrote in 1991 that “although chemical insecticide use in the United States has grown tenfold in both amount and toxicity since 1945, the share of crop yields lost to insects has nearly doubled during the same period.”
Just like with crops, avoiding a pest problem first is always preferred to having to eliminate one. There are a few ways to control pests naturally before resorting to chemicals. This is favorable because when chemical controls are used they kill both the pest and any beneficial insects that are present. These beneficial insects include bees for pollination and about twenty five other species — from parasitic wasps to earthworms. Some species enjoy such a good reputation they are available by mail order ( www.planetnatural.com). Before ordering any beneficial insects it is recommended that the area government entomologist is spoken to because some are restricted.
On a small scale, we experimented with using ladybugs to control aphids by catching the beetles in the garden and moving them to a tree that was inundated with aphids. We had already tried spraying the tree and they seemed to increase instead of die after the application. The ladybugs took care of the problem in days.
We’ve learned many natural methods for controlling pests in our garden, but it isn’t always easy or practical to expand what we have learned into the field.
For example, we had been stocking our old garden plot with eggshells for years. Not only did this solve a lot of our blight issues that stemmed from deficient levels of calcium in our soil it also virtually annihilated the cutworm problems we had been having. But to move this cure into a field of canola would be difficult. We have found that diatomaceous earth works just as well and can be added to the seeder at a rate of about four litres of powder for every 100 pounds of seed. The operator must take precautions against inhaling the diatomaceous earth as it can cause lung damage.
Cutworms are found at a depth of five centimetres so seeding should be at least this deep. Not only will the diatomaceous earth decimate the cutworms it will also add some minerals to the soil itself. Earthworms shouldn’t be harmed because they are found deeper in the soil than this. United Kingdom researchers reported that the majority of cocoons found were at 25 centimeters.
The other problem we have is controlling flea beetles. Luckily, we don’t live in an area that grows canola. In fact, the closest field is probably about 45 km away, but when combining starts we get clouds of them flying over.
Natural control of flea beetle starts with being clean. Adult flea beetles over winter in plant debris and are particularly fond of tomato and brassica family plants. This could explain why after the first time flea beetles found our farm they have never left.
Flea beetles are causing a problem with a grazing project we have wanted to expand on. For the last few years we have wanted to expand our growing of turnips as a fall feed for our livestock, but we don’t want to use chemical control because the pesticides have a long withdrawal and any residue would be stored in the fat of the animals grazing them.
Organic growers have recommended using trap crops to manage the issue. Last year, we grew one row of turnips as an experiment. Other farmers told us they were hard to grow here due to cabbage worms and flea beetles. The worm damage was manageable because the animals didn’t care if there were holes in the leaves. The worms came first and we used diatomaceous earth sprinkled on them for control, which worked instantly. Then the flea beetles came.
Even though there was diatomaceous earth on the leaves, by the time we noticed their arrival it was already too late. We checked the plants almost everyday.
Trap cropping, in which other plant species that the pest enjoys eating are planted near the main crop to draw the pest away, offers some possibilities for flea beetle management. Apparently, the most practical trap crop in my area is radish, seed of which is widely available. Research has shown that planting this trap crop about every 55 yards between rows of cabbage, broccoli, or cauliflower (or as a border around the field) can do an exceptional job of protecting them. To retain effectiveness, reseeding of the trap crop may be necessary, especially if the pest destroys the first planting.
If the trap cropping doesn’t work on its own the flea beetle does have predators. We will have to try and encourage them to live in the area. These are toads, which eat them at any stage of development, as will chickadees, vireos and purple finches. Ground beetles and parasitic wasps will hunt them. We have observed all of these predators in our area and we have been feeding chickadees all winter so we are hoping they will stay and help us fight the flea beetles for the summer.