The best time to spray is not when many may think it is, says Dennis
Gardisser, the president of Arkansas-based WRK, a company that develops
aerial spray monitoring equipment.
The best time to spray is not when many may think it is, says Dennis Gardisser, the president of Arkansas-based WRK, a company that develops aerial spray monitoring equipment.
| Dennis Gardisser, retired engineering professor, says the best time to spray is mid-morning.|
The retired University of Arkansas engineering professor says the best time to spray is mid-morning when there is some air movement and before the heat of the day sets in – not first thing in the morning when conditions are calm.
“It doesn’t matter what kind of delivery platform you use, as long as the chemical is spread evenly,” says Gardisser, who has 32 years’ experience in crop spraying. “If you miss even one plant, it could be subject to disease. That’s why you need to plan your spraying patterns carefully.”
He suggests it is better to spray into the wind as well as along the down side of an irrigation unit rather than in the jump. “And go in different directions,” he says. “You are more likely to miss a spot if you always apply your chemical in the same direction.”
Application height is also a factor to take into consideration when spraying, Gardisser notes, adding that spraying from 10 to 14 feet above the ground is the optimum.
“You get the least drift that way,” he says. “I have been involved in a lot of litigation where fungicidal drift was involved.”
One of the worst scenarios for spraying is when there are very high cross winds, says Gardisser, adding that it’s possible for some rows to be missed in those kinds of flying conditions.
He also recommends spraying right to the edge of the field in the areas that stay wet the longest.
The size of the droplets that are sprayed is very important, he points out. “Smaller is usually better,” he says. “The ideal size is between 300 and 325 microns.”
According to Gardisser, the boom placement is also a key factor whether in aerial or ground spraying. The new electrostatic booms can provide good overall coverage, he says, but only if the applicator use a huge volume of air.
“It is most important to communicate with the grower when developing a spraying plan,” Gardisser says. “If there are spots you can’t get to, you have to tell the grower.”
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