Spray Drift Management

Spray Drift Management
Drift has been a problem for years. To some degree, all sprays can and do drift. The objective is to keep spray drift within reasonable limits, and off sensitive property. Always keep in mind that pesticides are carried along with the spray drift droplets. And quite naturally, herbicide drift is the one that is obvious and often expensive.

Unfortunately spray drift complaints often involve non-farm situations such as adjacent property owned by folks that do not want pesticides on their property. Be a good neighbor and cooperate with their wishes. You might stop by for a visit and let them know what you are doing, and why.

Spray drift is most often caused by the small droplets(less than 100 microns) within the spray cloud. These small droplets are likely to evaporate, becoming even smaller and having the potential to drift even farther.

The optimum size for the spray cloud VMD is 400 microns. VMD is an expression of the droplet sizes contained within the spray cloud. Half of the spray droplets are smaller and half of the spray droplets are larger than 400 microns. This 400 micron spray cloud contains enough droplets for adequate target plant coverage, yet produces a minimum of smaller drift prone droplets.

One technique for managing drift is the use of drift control agents. There are several types available ranging from emulsified oils to polymers. Your local ag-chemical supplier probably has one that will give you good results.

Another critical component of drift management is wind management. Excessive winds and gusty winds are often the cause of drift events. Especially when the winds are blowing toward sensitive plants. When the winds are wrong, wait. Even if “wait” means “tomorrow”.

You should also keep the spray booms as low as practical to reduce the potential for spray drift.

A lot has been covered in this blog. Perhaps we can do another and further examine some of the components of sprayer adjustment and operation. Meanwhile, you might want to pick up some literature from the spray equipment companies such as TeeJet.com. They are a great source of information, as is the Cooperative Extension Service.

In the meanwhile, keep your sprayer clean. Check your calibration frequently. And be a good neighbor by avoiding spraying when a drift incident just might be one result you did not plan on.

--Tom Crumby