Chemical Wind Drift

WIND DRIFT & IT'S LIABILITIES

• Wind Drift and How to Prevent it
• Detecting Damage

Wind Drift and How to Prevent it

Drift is fast becoming a common term in our "growing" vocabulary. It is also very quickly becoming one of the foremost concerns that we are going to have to continually deal with from here on in our farming operations.

Whether its row-crop, grove, vegetable, nursery, tree farming or even landscape maintenance, any time we contemplate spraying, we are going to have to do so with drift prevention in mind.

How do we do it?

First and foremost, we must recognize and understand how our specific applications can produce drift, and how much. Then, we must use as much common sense as possible to correct that situation and, if necessary, get help from Extension agents, specialists and even colleagues. Of course, there are several basic steps that you can take to start preventing drift when you spray and most of these involve an understanding of how spray is produced and works.

1. Droplet size: The higher the pressure, the smaller the droplet.

   The smaller the droplet the greater the drift. You can always reduce the pressure to a certain extent , without changing the nozzle and get less "fogging". This will allow you to put the material on the plant and not into the air. If you reduce your pressure too much, you will get large droplets that will drip off the foliage and not give you coverage. When you reduce your pressure, you will also be lowering the flow through the nozzle, so it might take you longer to spray than before.

2. Wind Speed: 2 to 10 is the formula.

   2 mph to 10 mph wind is what is recommended to keep drift down. Don't spray in calm conditions, thinking you are not going to drift. Wrong!! especially if weather is warm. Of course, any wind over 10 MPH will pick up and carry your drift even further. Remember also to spray in a manner that the wind does not carry your drift over to the neighbor's, or into the road, river, lake, etc.

3. Directed Spray: Drive it, don't let it drive you.

   An air-blast sprayer shooting clouds of spray upwards in the row between trees is a no-no. Aim your, spray at the foliage (the target, as it is called in scientific literature), don't shoot it into the air so that it will come down on the tops, don't shoot it down at the ground so that it will "bounce up" and give underleaf coverage. Figure out ways to direct the spray, so that most of it is trapped by the canopy of what you are spraying. Remember, whatever amount gets deposited, does not drift.

4. Calibrate: Adjust your equipment to the job at hand.

   Air speed in blowers, travel speed in boom sprayers, nozzle direction in hand guns, all these factors will help you control drift. Don't run your blower full blast if you can still penetrate the canopy with less air, slow it down and you will reduce "blow-by". Your boom sprayer may do a better job if you redirect the nozzles, install drops, adjust ground speed. You may be spraying with hand guns that are too long, too short, too something, and are not suited for your application. Find a way to get the spray closer to your target with less over-spray Check with your colleagues, competitors, specialists, someone will have a positive suggestion.

5. Chemistry: Additives, surfactants.

   There are several good drift control additives on the market. Use them. Also use surfactants as they tend to make the water "wetter" and reduce evaporation. Most farm chemical suppliers will be glad to accommodate you.

6. Equipment: Nozzles, Attachments, Machines.

   Spray nozzle manufacturers are developing and selling ""rift control" nozzles. Look into them and see if they will work for you. Don't run out in desperation and change all your nozzles before run a test to make sure this is the solution for you. Look into attachments, either manufactured or custom made such as shields, deflectors, etc. that will direct the spray the way you want it. Many times you can dramatically reduce drift with a piece of bent sheet metal or a carpet remnant. See how others do it. If you think your solution is in equipment, carefully evaluate as many machine as possible. Listen to the salespeople, but make your own decision - you are the expert in your operation and will have to live with your choice. Again, talk to your peers, ask everyone you can think of, get opinions and, when you are ready to decide, don't "undersize" . If you have a choice of sizes, get the larger, not the smaller.

7. Common Sense: Timing - know how to wait.

   Again, the key to all this is common sense, and patience. Don't rush into a spray job. Your hurry can cost you dearly.

Detecting Damage

Unless the spray being applied and drifting is a contact herbicide, such as Diquat, Gramoxone, etc., drift damage to other crops may not be evident for up to three weeks after the actual event. Drifting fungicides and insecticides and their sticker-spreaders can cause phytotoxicity in delicate foliage, especially in hot weather. If the chemicals are systemic, then the damage may not be seen for weeks.

Consequently, the way to detect is to be there or have someone in the location when it is "invaded" by drift. In other words, keep tabs on your neighbors, especially if you have seen or sensed the drift from their equipment previously. You may also notice residue on the foliage and later see tip burns, leaf curl, dry-out, even bud and fruit drop. It is not unusual to notice the damage a few rows in from the edge of the plot bordering the neighbor's property. This is because there could be a low barrier, such as a fence, which would cause the airstream carrying the drift to vault over the first few rows and land on crops that are further inside the field or house.

If the drift is contact herbicides, look for burn spots on the leaves, in the case of light drift, and, of course major damage in case of heavy drift. Burn spots from drift will generally appear on the upper surface of the leaves and very seldom burn their way through the leaf.

If your spots are visible from both sides of the leaf, look for fungus or insect damage, not drift as the culprit!

Remember, there is very little written to set actual parameters as to when and how you can spray legally. The rule of thumb accepted by most courts in the U.S. on wind speed is minimum 2 MPH and maximum 10 MPH Follow these rules and make sure that your neighbor is following them, too. Don't be bashful. Talking about this with your neighbor is the best prevention method. Remember, his actions can seriously damage your crop, and vice-versa. And, once the crop is damaged, the civil action can be disastrous for both of you.