It is not widely known, but more than 80 percent of the currently available biopesticides are in use by mainstream agriculture and are as effective as conventional, synthetic chemical pesticides, according to Pam Marrone, founder and CEO of Marrone Bio Innovations, Inc., based in Davis, Calif.

MARK VAN HORN, director of organic farming, UC Davis, reviewed cover crop practices with Wendy Rash, USDA, Woodland, at the organic production seminar in Modesto.

Biopesticides, commonly associated with organic farming, are processed through fermentation or extraction from natural sources for control of insects, weeds, nematodes, and plant diseases.

Marrone outlined prospects for the expanding industry during an organic production seminar in Modesto. She noted that although her company serves the conventional segment, it continues to give high priority to the organics market.

“There are fewer and fewer new synthetic pesticides coming on the market, and in the next five to 10 years, we think biopesticides can fill a lot of that gap,” she said, adding that the cost of developing a new chemical pesticide for registration under today’s environmental requirements runs $200 million and more. Biopesticides are less costly to bring to the market.

Although the biopesticide market accounts for about only about $1 billion of the global pesticide market of $33 billion, she said she expects it to continue to grow rapidly and a huge biodiversity of sources remains untapped.

“Most people think biopesticides are only for organic production,” she continued. “They are very good tools for organics, but more than 80 percent of the biopesticides are used in conventional agriculture, rotated and tank-mixed just like any other product.”

By EPA’s definition, a biopesticide must have a non-toxic mode of action such as suffocation, dessication, starvation, or mating disruption. Examples that have become common in conventional agriculture include Bacillus thuringiensis, plant oils, and pheromones.

Natural products which have direct modes of action, such as those that act against an insect’s nervous system, are considered by EPA to be chemicals and not biopesticides.

In addition to having a short field reentry interval and no issues with air or water pollution, biopesticides can be used for pest resistance management, because, unlike single mode chemicals, most have complex modes of action, making it difficult for a pest or pathogen to develop resistance.

Although she sees a bright future for the class of materials, Marrone said issues persist. “Among them is a perception of weaker efficacy – the ‘snake oil’ image we are always battling – but, if a pesticide product is registered by the California Department of Food and Agriculture, it has demonstrated efficacy.”

A survey in 2005 by the Biopesticide Industry Alliance showed that biopesticides are most often used because of perceived environmental safety, she said.

“The main reasons they are not used include a perceived lower efficacy, higher costs, and an over-all lack of awareness of them.”

However, a follow-up survey by the trade group in 2008 showed that in California the number of growers and PCAs having a positive perception of biopesticides rose significantly from the earlier survey. When asked why, respondents were unable to indicate what specifically caused the increased awareness.

Marrone said the industry is increasing its efforts to improve awareness of biopesticides, including an online continuing education course.

Marrone Bio Innovations has primarily focused on its Greenmatch burndown products for weed control, which is the highest cost borne by organic growers.

Its Regalia SC, an extract of giant knotweed, is a new tool for fungal and bacterial diseases on fruit, vegetable, and ornamental crops.

The company is also developing an organic, systemic herbicide having the same effect as glyphosate products, and a selective rice herbicide is on its horizon. Other companies are working on a group of nematicides.

The seminar also heard about the role of cover crops in integrated organic operations from Mark Van Horn, director of organic farming at the University of California, Davis.

“Experience has shown that we need a lot of different tactics to in long-term success in organic farming. Many have figured out how to maximize natural processes. A complete understanding of the biology and ecology of the system is essential,” he said.

Prior to selecting a cover crop from among the several brassicas, legumes, and grasses, the grower must have clearly defined goals. The results will hinge on the species selected. Potential benefits of cover crops range from a source of nutrients and cation exchange to hold the nutrients to soil tilth, water penetration, and beneficial insect habitat.

“But cover crops don’t come free,” he said. “They have direct costs and risks. They require seed and seeding. In some parts of the state in some parts of the year you can get by with a rain-fed crop, but in others you need to irrigate.

“If not managed properly, they can cause weed and other pest problems. Sometimes what is best for your cover crop can be at odds with what is best for other crops you may have.”

Van Horn recommended that growers consult available UC publications and learn both the beneficial and harmful insect pests a cover crop may harbor.

Generalizations are few, other than the more closely related your cover crop is to your cash crop, the more likely pest problems can be.

He also suggested that cover crops be rotated just like cash crops are.

Allowing that the principles for soil and plant testing are basically the same for organic and conventional farming, Mike Larkin, head of the Precision Agri-Lab at Crop Production Services in Madera, said deficiencies or excesses of certain nutrients can be a significant problem in many perennial crops.

He said that plants growing in the field make no distinction in the source of a nutrient. “They do want the nutrient in the right form, in the right place at the right time so it is available for the crop.”

In any event, “proper nutrient balance is the key to excellent crop growth.” In the case of nitrogen, a recently incorporated cover crop can actually tie up soil nitrogen and cause a deficiency until the residue begins to decompose.

“After you work with a system for a time, you begin to see what the equilibrium is, and the process repeats itself year after year.”

Soil and plant tissue sampling can help guide toward the grower’s goal by indicating long-term trends toward or away from nutrient balance, Larkin said.