Study: Using pesticides as-needed increases watermelon yields, doesn't harm corn yields

IPB News | By Rebecca Thiele

Published November 8, 2021 at 8:06 AM EST

Workers harvest 40 acres of watermelons from the Krueger Farm outside of Letts, Iowa. The farm, which also grows cantaloupe, pumpkins, squash, onions, peppers, cucumbers, tomatoes, and zucchini for sale at their own stand as well as local grocery stores are promoting locally-grown produce. They also participates in Farm Service Agency's (FSA) Noninsured Disaster Assistance Program, which provides financial assistance in the event of natural disaster that causes crop loss or prevented planting in order to help producers recoup costs. Photo by Preston Keres

Pesticide that’s applied to corn can sometimes find its way onto watermelon plants — harming pollinators that watermelons need. Purdue University researchers foundreducing pesticide can increase yields for watermelon growers and would likely save both farmers money.

Applying pesticides to seeds or to a whole field might be convenient and seemingly cheap, but it harms pollinators in the area and doesn’t do much for yield. Researchers found using pesticides as-needed didn’t change corn yields and watermelon yields went up. Indiana is one of the top states for both crops.

Jacob Pecenka is a graduate student at Purdue and the lead author of the study.

“So if you reduce and only spray when you need to, the pollinators are so much happier and that can actually lead to improvements in crop yield just by those pollinators visiting much more frequently," he said.

Pechenka said his team saw more than a dozen native bees and other insects flock to the watermelon fields that had less pesticide — more than the non-native honeybees nearby.

“Really surprising that even after the first year of putting these fields in, the wild bees were doing a lot of the heavy lifting as far as pollination services," he said.

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Pecenka said the money saved by using fewer pesticides balances out the time or money it might take for farmers to apply them more strategically on their fields. It can also encourage natural predators that control pests.

Purdue entomology professor Ian Kaplan also co-authored the study. He said people aren't always aware of sustainable farming practices outside of organic farming — but it's important that the public support these farmers as well.

"Ultimately, growers are putting their crops at risk potentially by doing this — and so the more support that can be given to encourage growers to potentially go out on a limb and take a chance," he said. "I think that's critical."

Contact reporter Rebecca at rthiele@iu.edu or follow her on Twitter at @beckythiele.

Indiana Environmental reporting is supported by the Environmental Resilience Institute, an Indiana University Grand Challenge project developing Indiana-specific projections and informed responses to problems of environmental change.