Greenhouse Pest Scouting Advice You Can Use Today

Parasitized Aphids pest scouting

Parasitized Aphids; Photo: Albert Grimm

Protecting your crop from insects and diseases often starts with scouting and monitoring. After all, it is much easier to control one area of the greenhouse than it is to treat an entire greenhouse for a large-scale outbreak.

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We asked growers and other experts from across the controlled-environment industry to offer their best advice on scouting. Here’s what they had to say.

Early Detection Is Critical

According to Albert Grimm, Head Grower at Jeffery’s Greenhouses in St. Catharines, Ontario, and Greenhouse Grower’s 2016 Head Grower of the Year, very early pest detection is crucial for the success of any biocontrol program.

“I would go so far to say that the outcome of the program depends more on early detection than on any other factor,” Grimm says. “Consequently, we involve everybody in scouting. All staff are asked to check the plants that they work with at all times. They don’t have to identify any pests. They don’t even have to know what they are looking for. We simply ask them to call one of our pest control specialists if they do find anything that looks like an insect or a mite.”

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Jeffrey’s Greenhouses uses standard scouting programs with yellow sticky cards and regular crop inspections by trained scouts, but these methods will only provide an alert to an infestation after the pest has already had a chance to develop.

“We use the data from these scouting programs primarily to determine how well our programs have worked and whether we need to change our methods,” Grimm says.

Grimm also offers three pieces of advice on improving your scouting abilities.

  • “Take a course in entomology. You really have to understand each pest organism in detail before you can effectively scout for it. Do not just concentrate on the look of the insect, but try to understand its behavior in the greenhouse.”
  • “Get a microscope. A decent stereomicroscope can be had for under $400.”
  • “Always use the same people, the same methods, and the same type of record, so you can compare pest populations over time. This can help you develop the ability to judge whether a population is still manageable or whether it is panic time.”

Learn more here.

The More Eyes, the Better

Michael Sassano, CEO and Founder of Somai Pharmaceuticals, says knowing what you’re up against during the various seasons allows you to stay ahead of the curve even when you don’t see bugs in your cannabis greenhouse. It all starts with paying attention.

“Look closely at the soil around the base of the row, and randomly pull a plant out of a pot and check the root structure,” Sassano says. “All growers can be involved in this process, and having more eyes is the best practice. Identifying a potential threat is the job of everyone.”

When it comes time for treatment, a mix of beneficials and sprays/drenches may be your best strategy.

“Mixing beneficials and sprays is complicated and requires true knowledge of IPM best practices,” Sassano says. “Additionally, you must be careful of the plant cycle and use specific sprays and drenches during specific phases.”

Learn more here.

Keep Good Records

One of the most important aspects of scouting, according to Andrew Luxon, IPM Supervisor at Four Star Greenhouse in Carleton, MI, is record keeping.

“Keeping good records lets you identify historical problems and come up with preventative strategies for future crops,” Luxon says. “In addition to planning for the future, good notes/records allow you to look into the past and determine if a given course of action had the desired effect.”

As it as most other greenhouse operations, frequent scouting is critical.

“The higher the frequency you can afford to scout a crop, the greater the chances are that you’ll catch a problem while it is starting to develop and before it is causing significant injury/damage,” Luxon says.

It’s also important to make time for scouting, even at smaller growing operations where resources may be limited.

“Prevention of a problem is much cheaper than treatment of a large outbreak,” Luxon says. “Try to make a commitment to scout once a week, and make a point of looking back at records as you acquire them and try to establish patterns in pest problems.”

As you work with a crop over time, you will start to internalize what is normal for that crop at a given point in its life cycle, and when it deviates from that norm, you will be able to quickly realize that.

“Pay attention to plants that aren’t behaving normally and dig down into it to try and see if you can find the cause,” Luxon says.

Learn more here.

Start With Seed Selection

Scouting for pests may be a critical component of greenhouse management, but when it comes to vegetable production, the process should start even before the plants arrive. Marjan Willett, Americas MD Protected Lead at Bayer Vegetable Seeds, offers a three-step approach that greenhouse vegetable growers can follow.

  • “Prevention starts as far back as seed selection,” Willett says. “Consider the pressure for certain pests and the diseases that can follow them. Then work with your consultant or sales representative to choose a variety that has the right amount of disease resistance.” Willett also notes that no matter how diligent and careful growers are to keep pests and diseases out, nature has a way of finding a work around.
  • “Inspect plants carefully as soon as you receive them from the propagator, because that’s your first opportunity to keep pests out,” Willett advises. “Look closely, turning over leaves to spot evidence of insect larvae.” Then bring in trained experts, consultants, or specialized staff members to monitor plants. They should come every week at the same day and time to walk the rows. If they see any signs of pests or diseases, they need to record it, so you can track where it is and immediately begin mitigation steps such as releasing their natural enemies into the environment.
  • Know which pests might be present at which times. “Right now, for example, white fly is a key pest for tomatoes. It carries tomato yellow leaf curl virus that looks like a mineral deficiency in the plant, but has to be confirmed in lab testing. Western flower thrips can be devastating to peppers. They carry tomato spotted wilt virus, and once you see it, it’s too late.”

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