Don’t coarser droplets reduce coverage?
Yes, they can, but it’s not important at reasonable water volumes. In most cases, coverage is very similar, and efficacy is the same for broadleaf herbicides and fungicides at 38 L/ac (10 GPA U.S.). Grassy herbicides require some caution – don’t use a combination of very coarse sprays and low carrier volumes, and do maintain higher pressures. Droplet number per square inch is more important than droplet size for determining efficacy. Pressure and volume should be adjusted to maintain at least 300 – 500 drops / square inch on water-sensitive paper, or 10-15% coverage.
