2014 Highlights: UC IPM Annual Report

Protecting Strawberry Fruit with Microbial and Botanical Pesticides

Strawberry research plots along the California coast. (Photo by S. Dara)

Lygus bug causes crop loss in many California crops. In strawberry, lygus bugs feed on the fruit, deforming it. California is the largest producer of strawberries in the United States and the world. The strawberry industry is valued at $3.4 billion and consists of 400 family-owned farms on 40,000 acres, producing 70,000 jobs. Important issues include reducing conventional pesticide use where strawberries are grown and preventing pesticide resistance development. A sound IPM program would do this while protecting this valuable crop from lygus bug damage and yield loss.

More research is necessary to show that microbial and botanical pesticides can work. Microbial and botanical pesticides consist of only 20% of the pesticides applied in strawberries and most of it is Bacillus thuringiensis against lepidopteran pests. Increasing their use is a goal of Strawberry and Vegetable Crops Advisor Surendra Dara. He would like to add additional tools to the IPM toolbox for growers and pest control advisors.

The benefit of using microbial and botanical pesticides is their lower toxicity to humans and their shorter persistence in the environment. Many are as effective as conventional chemicals. Rotating and combining microbial and botanical pesticides with conventional chemical insecticides can be an effective strategy to successfully use them for lygus bug management and benefit from their lower environmental and human health risks.

Dara tested applications of two entomopathogenic fungi, a botanical insect growth regulator, and diatomaceous earth mixed with applications of conventional insecticides. His results show that rotations with conventional insecticides can reduce lygus bug numbers in strawberry fields.

More work is planned to continue to find good combinations of chemical and nonchemical alternatives. Dara says, “A true IPM program is not limited to the rotation of chemicals with various modes of action, but should explore the potential of all tools for effective, yet suitable, pest management”. By increasing the use of microbial and botanical pesticides and continuing his work to develop a comprehensive IPM program in strawberries, Dara hopes to help growers successfully manage lygus bugs to produce a healthy crop while slowing the development of pesticide resistance and reducing the use of certain conventional insecticides that have been shown to pollute water bodies.