By Ramdas Kanissery
As the summer season of weed control kicks off in citrus groves, now is the perfect time to make sure your spray rigs are set up for success. Effective weed control depends on:
- Accuracy – Applying the right amount to target weeds
- Precision – Making consistent passes to avoid missed areas and spray drift
In many cases, poor herbicide performance is caused by two main issues: spraying at the wrong time and using incorrect application techniques. We’ve already covered timing in a previous article. Now, we’re focusing on the proper techniques for applying herbicides. Accurate and precise herbicide application methods improve weed control, protect trees and maximize efficiency, helping keep your grove weed-free.
CALIBRATE SPRAYERS FOR CONSISTENCY
To achieve effective weed control and avoid wasting herbicide or causing tree damage, it’s important to calibrate your spray equipment regularly. Do this at least once a year, or more often if you’re covering a large number of acres.
Start by checking each nozzle on the spray boom to make sure they’re delivering the same output. Uneven flow can result in over- or under-application. Be sure to inspect the spray pattern as well. A consistent, uniform fan pattern is essential. Streaks or gaps in the pattern can lead to poor coverage and missed weeds.
Find more detailed information on calibrating citrus herbicide sprayers here.
PROPER SPRAYER PRESSURE AND SPEED
Next, make sure your sprayer’s pressure and ground speed are properly set to match your target application volume. These settings will help you calculate the correct amount of herbicide to mix in the tank.
Be careful not to increase pressure too much. Higher pressure can produce fine or ultra-fine droplets that are more likely to drift into the tree canopy. If you need to apply a higher spray volume, it’s usually better to adjust your ground speed or switch to larger nozzles rather than cranking up the pressure.
BOOM AND NOZZLE POSITIONING
Proper boom height and nozzle spacing are critical for achieving even spray coverage. If the boom is too low or the nozzles are spaced too far apart, you may miss areas between passes. If the boom is set too high, the spray pattern can become too wide, leading to poor coverage and a higher risk of drift into the tree canopy. A boom that’s too high can also increase the chance of knocking fruit off low-hanging branches during spraying.
Off-center (OC) nozzles are commonly used for directed herbicide applications in citrus groves. The angle of the OC nozzle determines the direction and reach of the spray. Lower OC nozzle angles are ideal for targeting the weed strip along the tree row while minimizing contact with the trunk and foliage.
RECOGNIZE THE RIGHT CONDITIONS
Ensure that spray operators are trained to recognize when weather or field conditions are not suitable for application. For instance, windy conditions can increase the risk of drift. Very calm conditions may lead to spray lingering in the air due to temperature inversions.
Investing time in properly setting up spray equipment and training the application crew leads to more accurate herbicide applications, improved weed control, reduced chance of tree injury and minimal herbicide waste.
Ramdas Kanissery is an associate professor at the University of Florida Institute of Food and Agricultural Sciences Southwest Florida Research and Education Center in Immokalee.
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