Agricultural Plant Pest Control
Agricultural plant pest control covers field and specialty crops, including corn, soybean, wheat, rice, sorghum, and vegetables. The exam emphasizes scouting, thresholds, correct identification, herbicide selectivity, resistance management, preharvest intervals, drift, and calibration.
Core rules
- Identify the pest and crop growth stage before choosing a product; disease, nutrient deficiency, and herbicide injury can mimic each other.
- Use an economic threshold, not a calendar. Treat only when expected loss exceeds control cost.
- Rotate herbicide sites of action and insecticide IRAC groups; resistance is a population problem.
- Respect preharvest intervals, crop rotation and plant-back restrictions, and label crop sites.
- Manage drift with nozzle, pressure, boom height, wind, buffers, and temperature or humidity inversions.
- Protect pollinators and beneficials; avoid flowering crops when the label prohibits application.
Worked example
A 40-acre field has 30-inch rows; the label broadcast rate is 1 qt per acre. You apply a 10-inch band. Band fraction is 10 divided by 30 = one-third. Product per field acre is 1 qt times one-third = 0.333 qt. For 40 acres, 0.333 times 40 = 13.3 qt. The same fraction applies to carrier if the label gives a broadcast carrier rate. Reasoning: the treated area is one-third of the field, so product is scaled to treated area.
Traps
- Applying a broadcast rate to a band, which overdoes product per field acre.
- Spraying by calendar after the threshold has passed or before the pest is present.
- Ignoring plant-back intervals after a soil herbicide.
- Confusing disease lesions with spray burn or nutrient symptoms.