In focus

Photo © tomasz | Adobestock

If you have pests in your greenhouse, they were likely reported by a scout.

The first thing you need to consider when you think about scouting is who’s responsible for this vital task. Some growers have full-time scouts, some have part-time scouts, but for most operations, scouting is part of someone’s responsibilities — not an entire job description on its own.

Scouts could be site managers. If a greenhouse operation has multiple production houses, it could be the lead section grower of each. It could be all employees at the greenhouse. It could be the employees on the potting line or the ones managing inventory. In many cases, it’s the applicator.

Managers can empower everyone in their organization to scout. But you need to make it part of the job description. Scouting does cost time and, through that, money. You must give the people you are empowering to scout time to scout and be flexible about when they do it.

You should also provide some basic training on what scouting entails — though even without formal training, if an employee sees something that doesn’t look normal, they can report it, and you can use it as a point of data.

Every employee likely has one of the most powerful scouting tools right in their pocket: the smartphone. Have scouts take pictures of anything that looks off and text it to the grower.

Scouting tools

The tools of the trade can vary widely in price and effectiveness. If you ask a large amount of your employees to scout, you won’t outfit all of them with Canon Rebels and pricey magnifying lenses. But everyone should at least have the basics listed below. Here are some options:

Basic tools: smartphone, loupe, pen and waterproof paper, pruners, marking tape, flags, acetone with cotton balls, hand sanitizer, map (to mark where pest was found).

Midrange tools: digital magnifier, EC/pH meter, clip-on lenses for smartphone (ex. CamKix).

High-end tools: microscope, DSLR camera, laptop for image manipulation, clip-on lenses like olloclip.

Scouting tips

Start early.

Place colored (yellow or blue) sticky cards among crops as soon as possible in the spring and conduct visual inspections, which will help to avoid outbreaks. Check the sticky cards once per week, count the numbers of insect pests and record the number.

Position colored sticky cards appropriately.

To capture adult thrips (western flower thrips), whiteflies, shore flies and leafminers, place sticky cards just above the crop canopy, and attach to a bamboo stake with a clothespin, thus allowing the sticky card to be adjusted as the crop increases in height. To effectively capture adult fungus gnats, position yellow sticky cards horizontally near the growing medium surface. Also, place sticky cards underneath benches with soil-based or gravel floors.

Visually inspect plants.

Mealybugs, scales and spider mites, as well as eggs, larvae, nymphs and pupae, will not be captured on sticky cards. It is important to check plant parts during routine monitoring to determine the presence of non-flying insects and various life stages.

Check the undersides of leaves.

Be sure to regularly check the undersides of leaves, since nearly all insect and mite pests and life stages are located there.

Maintain accurate records.

Always maintain records of your monitoring efforts by collecting information on:

• all major insect and/or mite pest problems during the growing season.
• susceptible crops.
• location in the greenhouse — especially those areas near openings. Maintaining records will be helpful in allowing you to assess when and where “hot spots” occur.

Remove yellow sticky cards before releasing natural enemies.

Prior to releasing any parasitoids and/or predators, remove yellow sticky cards, as the adults of many parasitoids and predators are attracted to yellow and will subsequently be captured.

Raymond Cloyd contributed to this article.

Matt McClellan is editor of Nursery Management. Contact him at mmcclellan@gie.net