A weekly press release prepared by the staff of the Ministry of Agriculture, Food and Rural Affairs. If you require further information, regarding this press release, please call the Fergus Resource Centre at 519-846-0941. Office hours: 8:30 a.m. to 5:00 p.m. For technical information, call the Agricultural Information Contact Centre at 1-877-424-1300 or visit the OMAFRA Website:www.ontario.ca/omafra
HOW MUCH WIND MAKES IT TOO WINDY TO SPRAY?
by Helmut Spieser, Agricultural Engineer, OMAFRA
Spring has finally arrived and all manner of crops are either planted or are going in the ground. Some of the seeded crops are slowly coming up and so are the emerging weeds. Herbicides need to be applied shortly to catch these weeds when they are small. It has been a long winter and reviewing the basics of good sprayer operation has not been a major after-supper activity. It’s time to do a bit of a refresher on minimizing spray drift.
There are two basic types of drift – vapour drift and particle drift. Vapour drift is the movement of product vapours resulting from the application of pesticides. Environmental conditions at the time of spraying or post spraying conditions combined with product selection are the largest factors affecting vapour drift. The second type of drift is particle drift, more commonly referred to as spray drift.
Spray drift is the physical movement of a pesticide through the air at the time of application or soon thereafter, to any site other than that intended for application.
One of the most critical factors affecting spray drift is wind. Spray drift increases as wind speed increases. Nozzle manufacturers have brought new nozzle technology to the market in recent years that have significantly reduced the drift potential. Keep in mind that these air-induction or Ventura nozzles reduce drift-they don’t eliminate drift completely.
When people shop for new nozzles one question they invariably ask is how much wind can I spray in with these nozzles? The answer is not as simple as you would like.
Here are some spray recommendations from a number of “experts”:
ª Do not spray in winds greater than 8km/hr
ª Spray when wind speeds are between 3 and 16 km/hr
ª Do not apply when winds are gusty or in excess of 8 km/hr
ª Don’t spray in winds over 24 km/hr, ideally not over 8 km/hr
Before you pick your favourite, you should know that one of the above is actually a statement on a product label.
That means that this is the legal way to use this product. If you use this particular product you don’t have a choice, the label is the law. If you don’t follow label directions you are off-label. Feeling lucky?
Most people read labels to determine what pests or weeds are controlled and the product rate to use in different crops. Also on the label will be cautionary statements that address areas such as acceptable conditions at the time of application that include wind speed, temperature and relative humidity. Read the label thoroughly every year even if you used the product years past. Even though the product is the same, the label may have new information that has been added.
Back to wind. Everyone knows that the drift potential increases as the wind speed increases. This would lead an individual to assume that zero wind or absolutely calm conditions would be almost ideal to eliminate drift concerns. In actual fact, no wind conditions can result in significant spray drift problems. The drift problem may not occur at the time of spraying but a couple of hours after the spraying is finished.
Here’s what happens. Let’s say your spraying early morning and there is no wind.
You are using the latest air-induction nozzles which have good drift management capabilities. The temperature is cool and the humidity is high which means all the droplets stay as droplets. You finish spraying at 7:00 a.m. You think you have done a great job. Drift is the last thing on your mind.
As you were spraying, the larger droplets got to the target but the small driftable fines are floating in the air justabove the field. Yes, even air-induction nozzles produce some fine droplets. Since there is no wind these fine droplets are not blown off the field at the time of spraying. Since the humidity is high, these fine droplets are not getting any smaller and are still spray droplets. So we have small droplets of a burn off spray floating above the field. At some point in the morning the wind starts to blow and as soon as that slab of air containing floating droplets of a burn off spray crosses the line fence you have spray drift.This movement may occur a number of hours after you finished spraying but it will happen.
Calm conditions or no wind conditions are not a sprayer’s friend.
A little bit of wind is desirable to create turbulent air movement which will carry the airborne droplets down to the target.
REGISTER NOW! ENVIRONMENTAL FARM PLAN
by John C. Benham, EFP Program Rep
The next two-day EFP workshop is planned for May 28th and June 4th in the meeting room of Husky Farm Equipment, Alma. The workshop is from 9:30 a.m. to 3:30 p.m – no charge.
To qualify for financial assistance to improve the environment on your farm an approved Third Edition Environmental Farm Plan is required. For more information and to sign up for the workshop, please call John at 519-846-3394.
COMING EVENTS:
May 20 OMAFRA On-Farm Slaughter Meat Regulation Session – Stratford at the River Garden Inn, 10 Romeo Street North from 7 – 9 p.m. Please register by calling 1-888-466-2372, ext. 65382, or email kimberley.leclerc@ontario.ca.
May 31 OAFE / Country Heritage Park “Farms Food and Fun” Day – This agri-education venture for Halton & Peel students will also be open to the family on May 20th. Admission is $5.00. For more information, please contact: Lorna Wilson 1-905-878-1510 ext 26.
