It takes time for beneficial insects to establish themselves in a greenhouse environment and it takes time for growers to adapt as well. They have to educate themselves on insect biology and change the "spray and my problems are over" mentality.

It can take years for a biological control system to reach its peak of effectiveness, and during that time growers may see pest populations higher than they would like. Dramm & Echter Inc., an Encinitas, Calif., cut flower grower, is facing this situation right now. But president Bob Echter and head grower Jack Graham are committed to the program because they know beneficial insects could eventually lead to fewer pests, decreased control costs and higher-quality crops. For establishing this program, Dramm & Echter has been named a GMPRO Innovator.

The company's biggest experiment with biologicals has been ongoing for two years. Within a 30,000-square-foot range of hydroponically grown gerbera daisies, these beneficials are used:

* Amblyseius cucumeris and Hypoaspis for thrips.

* Eretmocerus and Encarsia for greenhouse whiteflies.

* Phytoseiulus and Amblyseius californicus for spider mites.

* Diglyphus for leaf miners.

Gerberas were chosen partially because, unlike other cut crops such as mums or roses, they are harvested without foliage.

"While you don't sell foliage with the stems, gerberas are susceptible to a wide range of pests, which makes things more difficult," Graham said. "And while physical foliage damage doesn't necessarily hurt the flower's appearance, high pest populations can reduce plant vigor, which reduces stem length, flower size and yield."

Goal: efficiency and safety

Echter believes biological pest controls will become more of the norm in the greenhouse industry and increased state and federal regulations will continue to limit the types of chemical controls growers can use. By getting started with beneficials now, he will be better prepared for the future.

"It's also better for us internally," Echter said. "Worker safety is always a consideration and we want our employees to work in the safest environment possible."

Worker Protection Standard re-entry intervals are another consideration. Traditional pesticide programs can limit what times employees are able to enter greenhouses, which can complicate business operations.

In two years, the effectiveness of the company's biological program has increased, but Graham said improvements are needed to achieve better control and efficiency.

"We're anxious for it to start working better. But we're gradually getting better as we gain knowledge," Graham said. "We want it to work and we've seen it used effectively at other locations. But we still have to make money. I guess you can say we're looking to the future but still keeping an eye on the present."

When the program goes wrong, it's usually just one pest that gets out of balance. Thrips, whiteflies and spider mites may be held at bay, but leaf miners get out of control. At times, Graham has had to spray traditional pesticides, killing the beneficials as well, and causing him to start the biological program over. This is a situation he tries to avoid because re-establishing beneficial populations is expensive.

Determining when pest populations are just too high is a tough decision.

"That's the $9 million question. When do you chunk it and start over?" Graham said. "Talking with [beneficial insect] suppliers, they say the growers that hold off are the ones that are successful. Biological control is a different mindset. With pesticide sprays, you get control in an hour or a day or two. With beneficials, it can take weeks or months because you have to let the insects go through their life cycles.

"If you're willing to wait, you do better, but you hate to lose crops."

Keys: scouting and suppliers

Biological control systems work best when growers have a good knowledge of how pests and beneficials interact within the greenhouse environment. Graham said the best source for this information is beneficial insect suppliers. They can help you solve problems and also have recommendations for "soft" pesticides that will help control pests and diseases without harming beneficials.

Scouting is also a key, since growers need to know the population levels of pests and beneficial insects. In the Dramm & Echter gerbera house, long strips of both yellow and blue sticky tape are used to trap insects.

Echter believes biological controls can be successful. In five years he expects the program to be effective and cost-efficient -- possibly less expensive than traditional controls. "One thing that is helping is that there are a lot more soft pesticides coming. As more chemicals that are friendly to beneficials come along, that will make our job much easier and will improve our success."

Dramm & Echter Inc. Founded: In 1973 by Jim Echter and Gene Dramm. Crops: More than 35 cut flower crops, primarily roses, lilies and gerbera daisies. Acres in production: 65 field, 21 under polyethylene greenhouses. Employees: 120. Major customers: Wholesalers and bouquet companies. For more: Dramm & Echter Inc., 1150 Quail Garden Drive, Encinitas, CA 92024; (760) 436-0188; fax (760) 436-2974.

. © 1999 Branch-Smith Publishing