Protecting the environment and working with nature to control pest outbreaks should be a priority for every vegetable gardener seeking healthy, tasty crops. In study after study, organic growing methods reap produce and fruit equal in quality and quantity to those drawn from fields treated with pesticides. How can this be?
Organic controls for pests include dispersing
beneficial insects, like ladybird beetles, in infested areas.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Another organic control method to use with
snails and slugs is to place a low, wide saucer filled with beer between your plants. The snails are attracted to the beer’s scent, fall in and drown.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Toads and frogs are welcome visitors to any garden, eating their fill of flying and crawling insects.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Pheromone traps combine an insect attractant and sticky-walled cardboard to capture flying and crawling insects, like
whiteflies.
Photo Credit: ©2002 Dolezal Publishing/Kyle Chesser
The answer lies in the dynamic of insect populations. As with other animals, insects are divided into two large groups: the herbivores (those that eat foliage) and the carnivores (which eat other insects). For any given population of herbivores, a small number of carnivores (or predators) exist to keep the population in balance. Pests that harm vegetable plants are drawn from the more numerous herbivore group. These plant-eating insects reproduce quickly because predator insects, which reproduce more slowly, easily deplete their ranks.
When pesticides are applied to an insect population, most of the plant eaters – and nearly all of the predatory insects – are killed. Of the small number of each type that remain, the herbivores bounce back faster than the carnivorous insects, since few predators remain to stem the tide. Even more pesticide is needed, then, to control this pest population boom, and the natural balance that once held the two populations in check is destroyed. Pesticides, therefore, aren’t always the best method of action to take.
Scientists studying these control outcomes have reached general consensus about the best ways to manage infestations of harmful insects. The USDA now recommends following an approach called Integrated Pest Management, or IPM, to best take advantage of the natural dynamics of insect populations. With IPM, a small amount of residual crop damage occurs, but surprisingly, that damage is little more than what would be the case if crops were treated with pesticides.
IPM calls for using progressive steps of control, depending on the severity of the infestation. The first defense in vegetable gardens is planting vegetables that are healthy and naturally resistant to common diseases and some insects. Then keep your garden healthy by employing good watering, fertilizing and cultivating practices. Healthy plants are best able to fend off early attacks by insects until predator populations can bring things under control.
Another way to help control pest infestation is to separate your plantings by dividing large numbers of plants into groups for different spots in your garden. Insect pests are specific to each plant species, so separation can help limit large populations. Instead of putting all your vegetables in one section, for example, try growing some inground and others in containers or raised beds.
Finding an infestation in the first place is the best way to limit its spread. Inspect your garden at least weekly, looking closely for signs of insect activity. Eradicate all weeds, since native plants frequently host pests, and turn over leaves and look for chewed or rasped stems.
If you find pests, pick them from the plants or wash them off using a spray of clean water from the garden hose. Prune off infested foliage and destroy it. Seek out any egg cases and remove them as well. (Most infestations can be controlled easily at this early stage.)
When an infestation proves resistant to these hand controls and damage still occurs, apply minimally-toxic controls like horticultural oils or insecticidal soaps directly to the pests (avoiding broadcast spraying). As with all products, be sure whatever you use on your vegetable plants is recommended for the specific plant and pest you intend to treat, and carefully read and follow all label warnings and instructions.
