Strategy Is Key to Healthy Greenhouse Crops
October 21, 2020 
Successful greenhouse pest control relies on several factors — clean conditions, quality seed treatments, and mixing active ingredients to avoid resistance.
Photo courtesy of Germains Seed Technology
Greenhouse production introduces some crop protection challenges field vegetable growers would not normally face.
Take labor. Enclosed spaces raise the stakes for worker safety. Then there’s the way humidity and high plant densities all but embrace fungal diseases.
Those plant concentrations speed up another perennial grower challenge: if one active ingredient is applied too often, you’ll soon have a greenhouse full of resistant bugs or fungi.
We reached out for tips on how to handle these serious challenges.
Counter the Disease-Friendly Environment
Growers tend to look at the positives of controlling the environment within high tunnels and greenhouses. You can protect crops in ways you just can’t in a field.
But greenhouses have more humidity and more densely packed plants — perfect conditions for just about any disease. What can you do to cut down on outbreaks?
“This is the way I look at it — use everything we have,” says Bond McInnes, AgBiome’s Technical Service Manager, Eastern U.S.
Using everything translates to keeping the indoor range clean to an extent that’s impossible in a field.
“Good sanitation practices need to be practiced throughout the life of the crop, and they apply to everything associated with that crop, from seeds to plugs/transplants/clones, to people, to the growing structures, media, and more,” says Michael Brownbridge, Biological Program Manager, Disease Control Management at BioWorks.
That can mean everything from having workers walk through a disinfectant as they come in to keeping all debris off the floor.
“You really have to take a holistic view and ask, ‘What can I do to prevent and eliminate pests and diseases before the crop is even inside the greenhouse? What steps can be taken to prevent their transmission and spread?’” Brownbridge says.
And that’s a different way of thinking for field vegetable growers.
“You can’t sanitize or pull off leaves in a field, but you can in a greenhouse,” McInnes says. “Exclude organisms from coming in. It’s amazing how easily they come in through air or water.”
These precautions include your crop seeds, too.
“Rather than the standard hot water treatment to rid seed of pathogens, we have developed both conventional and organic seed disinfection processes that remove seed-borne pathogens without damaging germ and or reducing shelf life,” says Stacy Davis, Marketing Manager for Germains Seed Technology.
Help Your Team
Keeping your greenhouse clean and tending the crops is labor intensive. Our experts urge you to find ways to reduce repetitive tasks.
The cost of a re-application can be higher than adding another chemical to your tank, points out Bill Abetz, Account Manager, Professional Markets at Atticus.
“Programs today should include a mix of older, less expensive, as well as some newer chemistry, along with some nutritional products to stimulate overall plant health,” he says.
Preventing Resistance
Due to high costs in developing new chemistries, not to mention 10- to 20-year-long runways to market, very few new synthetic active ingredients are hitting the market. And fewer chemistries almost always equate to more resistant insects and diseases.
Luckily, biologicals have hit the market to supplement these controls and reduce resistance. Biologicals, by their nature, are broad spectrum controls. And so far, growers are reporting no resistance issues related to the product.
With such an array of tools available, managing resistance is a lot easier. The challenge there? Learning how all these products work together.
How to Find Great Info
With so many new products and methods available, how do you research what will work best for you?
Hit the books, says Andy Seckinger, Marketing Manager at OHP. Here are his tips on how to do that effectively:
Start cataloging information sources. In this no-contact environment, this means computers, smart phones, etc.
Use your smart phones to send plant pictures with problems to your technical resources.
Consider joining your state organizations for access to more information or educational opportunities.
Turn to private consultants for technical assistance. Great examples include “Ask Ann,” a service from Chase Research Gardens; local suppliers such as OHP or others (most have 800 numbers and websites). Do not forget the distributor sales reps with whom you have a relationship.
Take advantage of enewsletters and magazines for information and not just confuse these with spam junk mail.
“Going back many years, we had an extensive Cooperative Extension Service and county agents,” Seckinger says. “Unfortunately, these sources have been minimized.”
For that reason, Seckinger urges you to consider accessing other resources as a cost of doing business. That cost doesn’t necessarily refer to money. It can also translate to loyalty to the companies and distributors who are supplying the knowledge. Or to paid consultants, he says.
Whatever your challenges, the most important solution is your ability to problem solve.
“Growers are very inventive,” says McInnes. “They learn how to adapt. I think they can be successful.”
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