Photo courtesy of Bob Dickman

Dickman Farms was looking for a better way to control insect pests when it turned to using biological controls. The insects in its houses were developing resistance to the sprays, and the REI for these products resulted in lost productivity, not to mention were an inconvenience.

“The main reason we switched over was resistance to chemicals that controlled western flower thrips,” says Bob Dickman, greenhouse manager with Dickman Farms. “It’s very difficult for insects to become resistant to being eaten or parasitized.”

Dickman Farms is a fourth-generation, family-owned wholesale greenhouse and retail operation that first opened its doors in 1903. Dickman Farms consists of 10 acres of greenhouses and a full-scale garden center/retail store.

It is located in the Finger Lakes region of Central New York. Starting out with a few thousand young plants, it now sends more than 10 million starter and finished plants throughout the country and into Canada.

In one case, Dickman says they fogged an entire range with a popular pesticide used in the greenhouse industry and burned 2,000 mixed baskets. It had become an time-consuming endeavor with decreasing value for the business.

Enter biocontrols. The Dickman team began to learn all they could about biocontrols via trade shows, the internet and trial and error. They also took the advice of other growers who were already using this approach to insect control, including Ronald Valentin, who introduced the company to this method six years ago.

Graphic courtesy of Rose Buitenhuis, Vineland Research and Innovation Centre, with pictures from OMAFRA and Liette Lambert

Advantages of using biocontrols

There are many advantages to using biocontrols over traditional sprays, one being that you don’t get the foliage wet when using biocontrols like you would with chemical sprays, Dickman says.

“We don’t need to overhead spray chemicals on open blossoms during peak production to combat thrips and aphids,” he says. “Keeping the flowers and foliage dry has helped the overall plant quality and reduced fungal and bacterial diseases. When we would spray overhead for thrips and aphids, we would wet the flowers. We would then have to go back with a fungicide.”

At Dickman’s, the REI for the chemicals they used was at least 12 hours, resulting in lost productivity.  

“It was very difficult to get workers back into the greenhouse areas that were treated during the work day,” Dickman says. Another important advantage of using biocontrols is not having to worry about the potential negative health impacts from using chemicals. Biocontrols are also more in tune with consumer demand for pesticide-free plants, he says.

In terms of economic benefits, Dickman says there are the obvious savings in labor in terms of the amount of time it takes to spray a crop and the lost productivity when a house is closed up after it is sprayed. Also, fewer workers need to be licensed to apply pesticides, and the potential for a lawsuit over a pesticide exposure is eliminated. In terms of immediate savings, Dickman Farms reduced its chemical use almost immediately, from 1.0 percent of sales to pay for chemicals in 2012 to 0.9 percent in 2013.  

“2018 has been our best year yet for biocontrol.” –Bob Dickman

And finally, the effective use of biocontrols will ensure that plants aren’t being delayed from being shipped due to having to spray an infected crop before it gets on the loading dock. This would delay shipping at least until the REI period is over.

Using banker plants

Banker plants play an important role in Dickman’s biocontrol program. The banker plants provide an alternative food source for beneficial insects, should they run out of the pest insect, and in some cases a reproduction site for them, according to Michigan State University Extension specialists.

For instance, pollen from ‘Purple Flash’ ornamental pepper plants will provide food for the insidious flower bug (Orius insidiosus) should it run out of thrips to prey upon.

Oats and wheat will provide a food source for the beneficial insect Aphidius colemani should it run out of a supply of aphids. And Dicyphus hesperus will dine on plant sap should it gobble up all the whiteflies in the greenhouse.

MSU experts recommend about 100 pepper banker plants per acre of production space. Mullein is another banker plant they recommend. It is used for biological control of whitefly that potentially infect poinsettia crops, as well as tomatoes and cucumber cropping systems. Forty mullein plants are used per acre of production space.

Dickman’s uses oat banker plants for aphid control and ‘Purple Flash’ ornamental peppers for thrip control on Lobularia. It also uses sachet packets for thrip control and beneficial nematodes to control fungus gnats and shore flies.

Dickman says their biocontrol program has been very successful, though it didn’t come overnight.

“2018 has been our best year yet for biocontrol,” he says. “Every year we get a little better at using biocontrols and the staff — not just growers — recognize problems quicker.”

Dickman says they don’t hire a person specifically for scouting, but it is necessary to have someone on board who has a passion for using biocontrols. Dickman Farms relies on two section growers to do most of the scouting, along with a garden center employee.

“The biggest challenge is being able to identify the greenhouse pests from the beneficial insects,” Dickman says. “When we first have someone start out scouting, they will scout with the section grower for the first three to four weeks so they can get trained recognizing the different insects on the sticky cards as well as in the crop.”

“Overall, we have better control with our beneficial program than we did with our traditional chemical application program,” he says.

The bottom line with biocontrols

“You have to be patient and be preventative,” Dickman advises. “Start out using small trials on specific crops you have struggled with in the past using chemicals.”

“If you have an outbreak of pests, biocontrols will never catch up to the population of the pest before too much damage has occurred,” he adds. “A grower will have failures in their biocontrol program — we have had plenty. [The] first thing is to learn from the mistake that has occurred, try not to make the mistake again and don’t give up on bios because you didn’t get the control that you had hoped to achieve. Lastly, seek out advice from other growers and suppliers. There is a lot of work that goes into launching a beneficial program. Make sure you have ‘buy-in’ from everyone on the team.”

Neil is a freelance writer/copywriter for the green industry. greenindustrywriter.com