- Ada, Oklahoma

May 18, 2013

Be a good neighbor with pesticide applications

Justin McDaniel OSU Extension Educator

Ada —

Being a good neighbor with pesticide applications means thinking first, about what your pesticide application might do to harm your neighbors crops. This is not only good citizenship, it is also the law. Pesticide labels state that you must make every effort to reduce the risk of drift to non-target species, and there are state laws that require some pesticides not to be used after certain dates to protect the crops of others. Always read the label of any pesticide before you use it and consider what may be downwind from you that may be harmed by that pesticide application. Making good pesticide application decisions will help reduce your risks of off target herbicide damage. Failing to make good application decisions could make you financially liable for any harm that you do. So how can we utilize the agricultural production practices we need to be productive, and at the same time do no harm to our neighbor’s livelihood?

One of the ways would be for us to try and keep informed about what is going on around us, and then making herbicide application decisions based on trying to eliminate any harm to others crops. Just knowing when grannies garden is up, or when the cotton has been planted, or where that vineyard is located will go a long way in helping us make decisions about when to spray and what herbicide we can use. The Oklahoma Department of Agriculture is attempting to help us out by creating a website that landowners can log onto and locate a map where vineyards are located or where cotton may be planted.  The map also allows people that have organic production, or specialty crops, to mark their farms on the map. Producers wishing to spray pesticides on their property can then up load the maps and be able to make informed decisions on what, when, and under what weather conditions they should spray. This map also shows producers the areas in the state that have legal restrictions on when and how auxin type herbicides can be used.

 This map can be found at:

It is a simple map to navigate around, but if you have problems, or do not have internet access, your local county extension educator can get the site up on his office computer and help you with your pesticide application decisions.

 Another way to reduce risk to neighboring crops is to follow best management practices like the ones listed below. These practices will help producers avoid off target movement of herbicides in sensitive areas:


Best Management Practices.

1) Select an herbicide that is low volatile or non volatile. Volatilization is the movement of chemicals through the air in a gaseous form, usually following wind movement. When you can smell perfume coming off of the lady five rows over from you in church, this is an example of volatilization. Herbicide labels will warn you of possible volatility concerns so be sure and read that label.

2) Check the ODA map mentioned above for any sensitive crops or herbicide cutoff dates in your area.

3) Use spray equipment, application pressures and spray nozzles that produce droplet sizes that are greater than 200 microns. This information is readily available in sprayer parts manuals that sell nozzle tips or from extension publications via the internet.

4) Avoid perfectly calm days. Calm winds can lead to temperature inversions that can move small herbicide particles long distance. Inversions occur during calm conditions when there is little air mixing. Basically small droplets can hang in the air as a concentrated cloud that can then move to adjacent areas once the wind picks up. A light wind causes enough mixing in the atmosphere to keep this cloud dispersed.

5) Only spray when winds are 10 MPH or less. When the wind speed doubles, research indicates that there is a 700 percent increase in drift, when readings were taken 90 ft. downwind of the sprayer.

6) Select the lowest boom height possible while still getting good coverage of the target plant species. Research shows that when the boom height is doubled, for example 24 to 48 inches, the amount of drift increased 350% at 90 feet downwind.

7) Leave a large buffer zone unsprayed in areas where sensitive crops may be affected. When the distance downwind is doubled, the amount of drift decreases fivefold. This means that when near sensitive crops, leaving a large buffer zone will decrease the chances of particle drift causing harm to that crop.

8) Use a drift control agent when spraying near sensitive crops. Drift control agents work to keep the spay droplet size uniform reducing the amount of fine spray particles that can move down wind easily.

9) Treat pasture weeds as early in the spring as possible. Small pasture weeds are easier to kill and less volatile chemicals can be used while still maintain the desired control. Treating earlier also means treating in lower temperature environments. Research on 2,4-D vapor effects on tomatoes showed that as temperature decreased below 75 degrees, vapor effects on tomato plants was minimized. As the temperature got above 90 degrees, damage from vapor movement became significant with low volatile ester formulations of 2,4-D.

By following these simple best management practices we can go a long way in reducing the problems we may potentially have with pesticide movement to non-target areas and this will go a long way toward keeping all of our neighbors, good neighbors.