Effective Spraying

The objective of spraying is to deliver an effective, uniform dose of product to a target area in a safe and timely manner.

A cost effective insect pest control can be achieved, when the pest population reaches an Economic Threshold Level (ETL) and a product with the of right mode of action of the active is used. Satisfactory control isn dependent on a number of interrelated factors like dependent on the choice of product and equipment used in its application which further influences factors such as: compatibility, solubility, stability, foaming, suspension, time of application, surface tension, droplet size, drift, volatilization, coverage, adherence, penetrationand penetration.

One factor that doesn't receiveget much attention is the quality of the water used to spray the product. Water often comprises ninety-five percent (or more) of the spray solution. The quality of water used for spraying can affect how pesticides perform. Its effect on product efficacy is reflected in the success of your spray operation.

As a rule, most crop protection chemicals work best in a slightly acidic solution. Sometimes, water used for spraying is frequently alkaline. This may dramatically shorten the effective half-lives of many crop protection chemicals.

Acidifying spray solutions may be worth whileworthwhile. A safe pH for a spray solution is 4.5 - 7.0, with the best pH reading in the 5.0 - 6.0 range.

The term half-life refers to how long it takes for half of the pesticide to break down. If a pesticide is 100 percent effective when first added to the spray tank and has a half-life of 30 minutes, the effectiveness is cut in half every 30 minutes, becoming essentially worthless after 60 minutes. In general, the loss in effectiveness is due to hydrolysis; and the rate of hydrolysis is determined by pH, the chemistry of the pesticide, time of exposure in the spray tank, and the temperature of the spray water.

The ability of water to dissolve or suspend materials is influenced by the order of introduction of pesticide products into the spray tank. Mixing products out of order or combining products meant to be applied at different rates can lead to significant problems. Chemicals may not mix properly, causing poor product performance, clogged nozzles, product separation, adverse changes in pH and reduced solubility. Pesticide products work best when all components of the spray mixture are compatible and when they are added to the tank in the proper sequence.

Always consult product labels for the preferred order of introduction into the tank. Generally, you should add water into a clean tank, then add pesticides in the following order:

  1. Wettable powders (WP) and dry flowables (DF)
  2. Suspension concentrates (SC)
  3. Water dispersible gragules (WDG)
  4. Water soluble poders (WS) and granules (WG)
  5. Emulsifiable concentrates (EC), Emulsion, oil in water (EW)
  6. Wetting agents-Adjuvants

In most cases, agitation within the tank is necessary during mixing and to aid dispersal and effective mixing of formulation. When in doubt, use the “jar” method to make sure the products are compatible.

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