Protecting Crops with Pest-Controlling Plants

There are a variety of ways that farmers and gardeners can use plants to protect their crops from pests and diseases without resorting to chemical controls. For instance, some plants provide food and protection for insects that help control harmful insects.

Ladybugs are beneficial beetles that like crimson clover and hairy vetch. They find food, water and a resting place in the clover and vetch. Ladybug larvae eat harmful aphids, tiny insects that feed on many different kinds of crop plants.

Plants also help each other through their root systems. For example, scientists say the roots of the marigold flower reduce harmful nematode populations in the soil. Nematodes are tiny worms. There are more than ten-thousand different kinds of nematodes. And some of them feed on corn.

Wild mustard is another plant that releases a poison through its roots. This poison kills nematodes. It also kills some kinds of fungi.

A researcher at the University of California, Santa Cruz, said the wild mustard should be cut close to the ground after the first fifteen days. After that, it should be cut once a month. If left to grow freely, wild mustard will compete with the corn for nutrients in the soil.

Canadian researchers discovered that the dandelion weed can protect tomato plants from fusarium disease. Fusarium attacks the plant roots. It reduces the number of tomatoes that the plant produces.

Dandelion roots produce cichoric acid. This acid prevents the disease from getting iron from the soil. Fusarium needs iron to survive.

There are, however, plants that should never be grown together. The roots of the black walnut tree, for example, produce a poison that kills potatoes, peas, tomatoes and peppers.

Dying parts of the brassica family of plants produce a poison that prevents the seeds of some plants from growing. Brassica plants include broccoli, cabbage and cauliflower.

Plants with small seeds, such as lettuce, are especially affected by the brassica poison. A professor at the University of Connecticut said brassica plants should be removed from the soil after they have produced their crop.

Related topics:
Plants Invite Insect Allies to Dine on Pests
Try Natural Pest Control with These Insect-Repelling Plants

Source:
VOA News Service
Author: Bob Bowen
First published: April 1, 2005