Signs of herbicide damage

Herbicide damage is difficult to tell, because similar symptoms may be caused by several other things including; nutrient shortages or excesses, water excess or drought, wind driven sand or soil particles, high or low temperatures, mechanical damage, or other pesticides. However, general symptoms can be in the form of reduced leaf size and shortened internodes or that new leaves may turn yellow or have chlorotic spots, curling, cupping, and vein distortion of the leaves on some trees, plants may become more susceptible to disease and other pests, petiole and stem twisting and malformed leaves (such as effects by 2,4-D). An overall symptom from herbicides is the reduction in growth of the affected plant (from inhibition of cell division or other effects) and decline or loss of yield.

How to reduce Herbicide Drift

The first thing an herbicide applicator has to do is to read labels for droplet size requirements of the herbicide and then set up equipment to ensure drift minimization. A drift can be minimized by selecting appropriate nozzle type and pressure with due consideration for the weather conditions, most importantly the wind velocity and temperature inversions. Transport of herbicide away from the target area could be under the influence of gravity, buoyancy and wind. In this case, large droplets may fall faster than small droplets. In other words, the higher the droplet is released, the further it will move away from the target area because there is more time for the wind to move the droplet before it lands. Hence, an herbicide drift is closely related to boom or flying height. In drift prone conditions, boom should be operated at lowest height possible. Decreasing nozzle spacing will also allow boom to be operated at a lower height.

Temperature inversions would occur when warmer, less-dense air moves over cooler, denser air. The situation could create subtle horizontal air flows that can move concentrated amounts of spray long distances. Herbicide applicators should make clear understanding of the following aspects before and during herbicide applications;

(1) Before spraying

• Always check for susceptible crops in the area.

• Recognize all sensitive areas (wildlife and people).

• Know what is around the application site.

• Notify neighbors of your spraying intentions.

• When spraying, record weather and relevant spray details.