New York State IPM Program

In Greenhouses, Good Science = Good ¢

In the cold Northeast, heat costs money. And no one knows it better than greenhouse growers. With Mother’s Day just around the corner, growers are ramping up for one of their biggest sales days of year — which until now, has meant cranking up the thermostat.


Not any more. Growers want to save money and fuel. The unanswered question? How will pests — and the biological controls that help keep them in check — respond?


On the Fly: Fungus gnats look like tiny mosquitoes, but we are not their prey. These egg-laying machines just want the best possible home for their young. The problem comes when that home is a pot of pretty posies.

Take fungus gnats. These sneaky little flies lay tiny little eggs just below the soil surface. Before long their larvae are out and about, burrowing through the soil and nibbling off every growing root tip they bump up against. But if en route these fungus gnat larvae bump up against parasitic nematodes, invisible threadlike critters that eat them inside-out … well, that’s why savvy growers have turned to nematodes to even their odds in the plant-survival department.


Water Them In: No bigger than a deck of cards, this packet contains upward of 50 million hungry nematodes. Mix them into a tank of water, turn on the pump, open the nozzle — and water them in.

Cooler temperatures slow down both gnats and nematodes. If nematodes lag too far behind their larval prey under those conditions, we need to know. Our business, after all, is providing growers the best real-time information and guidance we can. Naturally, growers who provide real-world research settings for us are invaluable partners — because if it works for them, it’s likely to work for their peers.


We’ll collect lots of sticky cards over the season to help track how many fungus gnat adults squeaked past the nematodes compared to those in our control zones: the no-nematode and low-temp sectors. If our numbers come close to the numbers we got in our preliminary growth-chamber experiments earlier this year, we’ll be happy. Very happy.

See What Sticks: Bugs like yellow, which is why we use bright yellow sticky cards to monitor which critters are out and about in the greenhouse. It’s sticky work, but necessary for real-world results.

Author: Mary M. Woodsen

Pests and pesticides — both can cause harm. How can we protect ourselves the least-toxic way? IPM is the sound, sensible, science-based approach that works wherever you do. The New York State Integrated Pest Management Program develops and offers tested tactics for pests new and old, whether on farms, offices, orchards, schools, parks, vineyards, more.... Wherever you find pests, you find IPM.

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