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To Spray Or Not To Spray?

13 July 2011

US - To spray or not to spray may be the question of the season in the garden, said a University of Illinois Extension horticulture educator.

"Yes, it's a parody on a famous saying, but perhaps it will cause you to stop and think before grabbing a bottle of pesticide," said Martha Smith.

"Integrated Pest Management stresses monitoring your landscape and keeping a keen eye out for problems. We should be asking if it's a good time to spray or if there is an alternative.

"Most pest problems start out small. Perhaps an infested branch can be removed or critters can be picked by hand off a plant. It can save you time, energy, money and chemicals being added to the environment. If you seldom stroll through your landscape, you might not see a pest until it has consumed a major portion of your investment. By that time, a chemical control may be the only choice."

Smith offered some guidelines if you choose to combat garden pests with chemicals.

  • Read the label. Understand what the product is intended to do and the best timing for application. When during the life span of the pest is it best to apply? Correct timing will give the best control with the least amount of chemical.
  • Correctly identify the pest. Caterpillars resemble sawfly larvae, but the products to control them can be different. Also, is that caterpillar a true pest? If you choose a caterpillar control, don't question the absence of butterflies later in the season. Caterpillars can be voracious eaters, but the majority will turn into colorful butterflies.
  • Mix the material as directed. Avoid thinking that if one teaspoon is recommended, two teaspoons will be better. Effectiveness will not be increased by doubling the amount of chemical. In fact, higher concentrations can harm plants.
  • Follow all personal safety instructions on the label. A sleeveless tank top and flip-flop sandals are probably not the recommended protective clothing. Consider a long-sleeved shirt, long pants, eye protection, socks, closed-toe shoes and gloves even if they are not already instructed on the label.
  • Use measuring utensils; don't guess at amounts. Have a set of measuring utensils specifically designated for chemicals. Write on them "chemicals only." Don't use utensils that are also used in food preparation.
  • Spray on target. Don't apply a chemical across a 20-foot border when only two to three square feet require attention becaise it may not be necessary. Read the label to learn if the entire plant should be sprayed. Spray to the point of runoff and stop.
  • Application equipment should be in good working order. Leaks can lead to damage on non-targeted plants. Use equipment that is recommended on the label.
  • Spray when the weather is calm. Pesticide drift occurs when spray is carried off target by the wind. Drift can also be minimized by spraying at a lower pressure and using the largest nozzle opening that will still allow you to complete the task.
  • Avoid spraying during the heat of the day. Some pesticides will burn plant material if they are applied when temperatures are too hot. High temperatures can also cause some pesticides to evaporate and decompose quickly. Spray in the morning.
  • Avoid spraying before rain or before overhead irrigation, which will reduce the spray's effectiveness by washing the material off the target plant and possibly leading to groundwater contamination.

"Keep these spray guidelines in mind when selecting a pest control for your landscape," Smith said. "Monitor and identify the pest early. Consider your control options. Remember your control selection may not be what your neighbor would choose."

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