How To Transition To Biocontrols In The Greenhouse

Amblyline cu (Amblyseius cucumeris), part of Syngenta's Bioline product line

In this year’s Top 100 Growers survey, we asked how many of the largest operations in the country are using biological controls, and how much they’re using them.


We found that nine Top 100 Growers say they are using mostly biocontrols with some chemical controls. How long have they been managing pests and diseases this way and how did they make the transition from traditional chemical controls to biocontrols? We talked to Post Gardens’ Bill Tuinier and Grower Direct Farms’ Adam Van Wingerden to find out.

Grower Direct Farms: A Gradual Shift

For Grower Direct Farms, the transition to biological controls started five years ago when growers there began experimenting on a small scale to determine the products’ pros and cons. (For an explanation of the different types of biocontrols, see the Biocontrol Glossary.)

“In order to completely evaluate them, we needed to transition the whole operation,” says Van Wingerden. “The main impetus for changing was increased resistance to chemicals, increasing costs for chemicals, the regulatory environment and business disruptions in peak shipping due to pests.”

A main production difference that Van Wingerden cites as part of a biocontrol program is scouting. Having biologicals in place requires that scouting measures are followed more diligently. Growers fill out tracking sheets weekly to identify population trends and hotspots. With the time and resource investment required (he says these programs do cost more than traditional controls) Van Wingerden acknowledges that each greenhouse must determine how much it can spend on biocontrols and which crops can be treated with which products.

“We have found that BCAs are not able to provide the level of control we need on certain pests,” he says. For example, the operation has had trouble controlling aphids exclusively with biological control agents (BCAs), so the control strategy for fuchsia and calibrachoa has needed adjustment.

“In addition, fungicide compatibility with BCAs is an issue.”

To combat this compatibility problem, Grower Direct Farms is using fewer BCAs and more biopesticides, which are not affected by fungicides. Van Wingerden says the operation uses the Syngenta Bioline system as well as nematodes from Becker Underwood.

The operation’s experiences have been positive, so what will the future hold for Grower Direct Farms as far as biocontrols go? The learning curve continues, but for this grower, it probably includes a mix of BCAs, insect growth regulators and biopesticides.

“We believe that more work will continue to be done in these areas as well as fungicide compatibility to ensure success without harming the environment or BCAs that we’ve released,” Van Wingerden says.

Post Gardens: Scouting And Prevention

After a successful first attempt at controlling whitefly on poinsettia with help from Koppert seven years ago, Post Gardens has increased its use of biological controls. Post’s Bill Tuinier says biocontrols don’t eradicate insects, but they manage the populations to the point that pest counts are low enough to not cause damage.

“You can’t get worried about seeing a thrip,” Tuinier says. “But if you see three on a gerbera daisy, now you have a problem.” As with Grower Direct Farms, Tuinier says the new program has required the operation to be more diligent about scouting. Yellow sticky cards are moved around the greenhouse to reveal where the problem hotspot areas are. When a hotspot is found, that area is treated with a traditional control, while the rest of the house continues to be treated only with biologicals.

“The big difficulty is monitoring and scouting for the pests,” Tuinier says. “You can’t let up on that.” Cards are placed at one per 5,000 square feet and a spreadsheet carefully tracks hot spots by greenhouse zone and card number. Tuinier estimates that scouts are reading 100 cards per week.

“We try to leave one person in charge of that,” Tuinier says. “So that’s all that person does — take care of the cards.”

Another tip from Tuinier: Biocontrols work better in the winter when greenhouses are closed up tight and insects can’t enter through vents or fans. In the summer, there may be the need to use a traditional control to eradicate a problem and then start over again with biocontrols.

The use of biocontrols has eliminated the use of traditional controls in some instances. For example, Post uses Rootshield, which is for crops that are prone to root problems, like Easter lilies and poinsettias. Since Post started using Rootshield seven years ago, the operation hasn’t used fungicides on either crop. Tuinier says that Actinovate and Cease provide good control of Botrytis and powdery mildew.

Nemasys has also been a huge help to controls thrips larvae in soil.

“We typically use Nemasys on all of our cuttings and plugs,” Tuinier says. “We pretty much treat everything we put in the greenhouse with Nemasys, just so that it has protective nematodes on the soil. If there’s any larvae from thrips, it helps knock them down. That has been a huge help with the whole program.”

These insights into the best use of biocontrols are the a result of experience with the products. “There is a learning curve, but you have your traditional controls to fall back on,” Tuinier says. It took a couple of years before the growers at Post felt they had a handle on their program, but Tuinier says using biological controls is all for a good cause.

“You can justify doing it and you can justify not doing it. But ultimately, we’re not protecting the environment if we’re not trying to do it,” he says. “And we’re not protecting future generations. As far as our employees, we’re protecting them a lot more. They feel safer using biologicals than insecticides. It’s not all about money. It’s also about protecting your employees.”

Biocontrols Glossary

Here’s an explanation each type of biocontrol.

Biological Control: A method of controlling pests and diseases with other living organisms

Biological Control Agents (BCAs): Natural enemies of insect pests, including predators, parasitoids and pathogens

Biopesticides: Control products that are derived from natural materials, such as animals, plants, bacteria and minerals

Insect Growth Regulators: Products that prevent insects from reaching a reproductive stage, which reduces pest populations