April's Ag Advice by April Borders With the cost of pesticides today and all the scrutiny that the agriculture industry has been under, we need to try to get a handle on spray drift. There is a continuing concern about off-target drift and that concern has intensified in recent years. Part of this concern has to do with the increase use of chemicals such as glyphosate and another concern is the fact that more people are moving into the county.
We need to be careful with the use of our agricultural chemicals. We need to make sure that we are using these chemicals effectively and we are watching out for our environment. The EPA is tightening its restrictions on the use of chemicals and is trying to safeguard against drift.
In 2001 the EPA released a draft of the new pesticide label statement in which they propose guidelines that would prohibit spraying when the wind speed is above 10 mph. The rule is not final at this time but we can be assured that some maximum wind speed restriction will be included in the final rules. Wind speed is one of the key variables in drift.
So what can you do to reduce drift? Here are some suggestions.
1. Choose you chemical carefully. Many chemicals come in different formulations. An ester formulation is more susceptible to vapor drift when temperatures are high, while an amine formulation of the same product will be much less likely to volatilize.
2. Check the pressure that you are using to apply your chemical. As the pressure increases, droplet size decreases. Therefore, lower pressure reduces drift. Under most conditions, do not exceed 40 to 45 psi unless you are using a venturi-style tip designed for high pressure.
3. Ground speed. Avoid high ground speeds or major speed changes across the field. Spraying at high speeds is no different than spraying in high winds. High speeds also create a vacuum behind the sprayer, which can cause distribution in this area to be worse than along other areas of the boom.
4. Boom setup is very important. It consists of three issues: height, levelness and stability. Nozzle manufactures provide optimum height recommendations for nozzle type and spacing. Follow these as closely as possible.
If the boom is too high you will get drift, if it is too low you risk an uneven distribution of pesticide across the boom width. Make sure that your boom is level for uniform chemical distribution. Also make sure that your boom is stable. A boom that bounces excessively provides for poor chemical distribution.
5. Select a nozzle style that produces coarser droplets. Increase nozzle size, a larger capacity nozzle will reduce drift. Use the correct nozzle for proper chemical delivery.
6. Spray when wind speeds are less than 10 mph. If there is a slight wind, spray when the wind is moving away from the sensitive crop. Leave a buffer zone by the sensitive crop and spray that area when conditions are more conducive.
7. Keep a close eye on environmental conditions � wind speed, wind direction and temperature. Be aware of temperature inversions. When the air is very still and temperatures near the soil surface are cooler than the air above, no mixing occurs. Calm air can reduce air mixing so the spray moves slowly downward.
The pesticides can hover in a dense cloud above the soil surface and be carried off site by a gentle breeze.
8. Consider using new technology like drift reduction nozzles or boom shields.
9. Consider using a drift control additive when needed. Drift control additives increase the average droplet size produced by the nozzle. They can however affect your spray pattern so you might need to recalculate nozzle height.
Knowledge is power. This is such a true statement when it comes to our spraying program. The more you know about your chemicals and your equipment the more effective your control efforts will be. Take time to check over your spraying system. Make sure that it is ready for this spring. Take control! You might not be able to control Mother Nature and the weather but you can control other factors that determine the impact that your spraying program will have on your crops and the environment.
For more information contact your local Extension Office at 677-7111.