Pesticides, Influencing Factors in the Effectiveness and Efficiency of

A range of factors can influence the effectiveness and efficiency of pesticide application, absorption and retention to grass leaves. Reducing environmental contamination, maximising control of undesirable organism/s and ensuring cost-effectiveness of chemical use are primary aims from the use of any pesticide. Awareness of different influencing factors can help a grounds manager better achieve the desired aims to their fullest extent. Influencing factors can include the following:
1. Correct calibration and application / operating speed ensures the approved quantity of concentrate is applied to the target area. Excessive spray volume will encourage run-off whilst less than a label’s stated volume quantity will reduce the area covered and concentrate retained on a leaf.
2. Leaf surface and shape affects absorption and retention, with surfaces that are waxy, hairy, narrow and rolled being more difficult for pesticide absorption and retention than smoother, flatter, broader leaf blades. The angle of a leaf can also influence run-off or retention.
3. Additives, such as wetting agents, surfactants, polymers, and other adjuvants, can help either to reduce surface tension and/or improve surface retention of applied pesticides.
4. The size of the droplet should be just right for optimum applications, being- neither too small, in which case drift may be an issue, or too large, in which case they bounce or run off a leaf. Use the correct nozzle and pressure to achieve the desired droplet size (measured as Volume Median Diameter, VMD, in microns).
5. Conditions influencing plant growth. Slow, reduced growth will not absorb as much pesticide as an actively growing healthy plant.
6. Rainfall, just prior or just after application can reduce the potential retention of a pesticide. Check the ‘rainfast’ nature of a pesticide as different chemicals are more ‘rainfast’ than others.
7. A dense sward surface can reduce the evenness of contact from an application, especially where some plants grow over the leaves of other species.