Reduced-rate pesticide program

The reduced-rate pesticide program focuses on spray efficiency and effective spray application.Researchers at The Ohio State University (OSU) are teaching nursery managers how to cover more trees with less pesticide, which equals a significant cost savings.

The reduced-rate pesticide program concentrates on spray efficiency and effective spray application, including calibrating sprayers to more efficiently apply pesticides. Some growers have not ever calibrated their sprayer, which leads to uneven coverage of the tree or crop, said Randy Zondag, commercial horticulture educator and director at OSU. 
 
And uneven coverage may lead growers to believe they need to spray more. 
 
“We’re trying to get growers to look at coverage and not volume of liquid per acre,” Zondag said.
 
Growers who have adopted the program are saving between $200 and $400 per acre, per season, he said.

Less is more
Heping Zhu from USDA-ARS in Wooster, Ohio, developed this process. Zhu’s early research showed that more than 30 percent of the spray applied ended up on the ground. This meant growers were applying too much water.
 
The researchers also found that a sprayer has a certain capacity to cover an area, and once that level was reached it didn’t matter how much water a grower applied, the coverage would not improve.
 
“We also found that many growers were trying to spray too large of an area and coverage would not occur,” Zondag said.
 
Zhu looked for ways to reduce waste and determine coverage. The first trials looked at where nozzles placed the product.
 
“We found that many growers never turn nozzles off if they are not spraying at an object. We also found that many sprayers just spray into the air and cause a drift problem,” Zondag said.
 
Next came trials that reviewed several types of sprayers, including changing the travel speed, pressure and nozzles.
 
“We found if too much liquid was being applied, the best method to reduce waste was to change nozzles according to the need of the crop,” he said.

Computer help
Zhu developed DepositScan, a computer program that quickly evaluates spray deposit distribution on water sensitive paper or Kromekote cards. Growers can use this information to determine if the droplet size is correct and if they’re getting proper coverage. And if growers store this information in the computer, the program will identify when the nozzles need to be replaced. The program may be downloaded by visiting the USDA site.
 
“We want people to know how to choose nozzle size, maintain their sprayers and determine if they have the proper coverage to control pests,” Zondag said.
 
A successful reduced-rate practice requires prudent timing, appropriate chemicals, an understanding of the mechanisms of chemical action, pest life cycles, disease processes, and other factors that affect pest control, Zhu told an audience at the 2009 Farwest Show.
 

Spreading the word
Amy Fulcher, nursery crops extension associate at the University of Kentucky introduced the program to growers last year during a field day. 
 
Fulcher said it’s important that growers become more sustainable, and the reduced-rate program can help.
 
“The conventional 100 gallons (of pesticide) per acre is far beyond what is necessary, and that is what the program demonstrates in a very visual way with water-sensitive paper,” she said.
 
Green Ridge Tree Farm in Elizabethtown, Ken., has participated in the program for two years with an air-assisted sprayer on the 150-acre farm. Managers there have only targeted a portion of the farm with the program. Now, they are able to compare the results.
 
“We sprayed the half-rate and the full-rate on trees at Green Ridge, and growers were able to see how oversaturated the paper becomes with the full rate,” Fulcher said.
 

From skeptic to believer
Understandably, many growers are skeptical of the program at first because if it doesn’t work, they have a lot to lose, Zondag said. 
 
Greg Goodpaster, production manager at Green Ridge, was one who started the program with skepticism.
 
“We’ve just got our old ways because I have been in this business for 30 years,” he said. “We don’t like taking risks on insects when it comes to spraying them; we want to make sure we get them killed. I thought the half-rate program might not be as effective. I thought I might have to go in there and spray again because it might not do what I wanted it to do. Since I have been participating in the program, I have seen that it works.”
 
Fulcher said research shows promise for the program to be useful not only in tree crops, but other crops as well. 
 

For more: Randy Zondag, OSU, zondag.1@osu.edu; Heping Zhu, USDA-ARS, heping.zhu@ars.usda.gov; Amy Fulcher, University of Kentucky, afulcher@uky.edu; Green Ridge Tree Farm, www.greenridgetrees.com.
 
Aimee Nielson of the University of Kentucky’s Agricultural Communications Services contributed to this story.