Plant Health and Integrated Pest Management
The Plant Health and Integrated Pest Management domain tests diagnosis and decision-making rather than spraying. Expect questions on the IPM sequence, the disease triangle, distinguishing abiotic from biotic problems, monitoring and thresholds, biological controls, and the legal and safety rules that come with a pesticide label.
The IPM sequence
- Identify the pest or cause properly, monitor and count, compare the count with an action threshold, apply prevention and cultural controls, then mechanical and biological controls, then a pesticide as the last resort. Evaluate the result and record it.
- Prevention carries the most weight: right plant, right place, correct planting depth, sanitation, appropriate irrigation and spacing for airflow.
The disease triangle
- Disease requires a susceptible host, a virulent pathogen and a favourable environment. Remove any one leg and the disease does not develop, which is why airflow, drainage and resistant cultivars matter.
Abiotic versus biotic
- Abiotic injury is often uniform, appears suddenly, and follows a pattern: one side of the plant facing the road, one soil type, one exposure, or damage on many species at once. Consider salt, herbicide drift, drought, frost, pH, compaction and root damage.
- Biotic damage tends to spread, appears in patches, and shows signs: frass, webbing, feeding notches, fruiting bodies, lesions with margins. Look for the insect at the right life stage.
Pesticides
- The label is the law: rate, timing, PPE, buffer zones, re-entry interval and pre-harvest interval all come from it.
- Rotate modes of action to slow resistance, protect pollinators by avoiding applications during bloom and by timing to low bee activity, and complete the application record.
Worked example
A pin oak shows interveinal yellowing with green veins. This is iron chlorosis caused by high soil pH, an abiotic problem. Confirm with a pH test, then acidify or apply chelated iron; a fungicide would waste money and add risk because no pathogen is involved.
Traps that cost marks
Spraying for an abiotic disorder; applying a broad-spectrum insecticide during bloom; treating without reaching a threshold; skipping the application record.