Core: Pesticide Principles, Safety, and Regulations
Who regulates what
FIFRA gives EPA authority to register pesticide products; the Maryland Department of Agriculture (MDA) is the state lead agency that certifies applicators, licenses pesticide businesses, and enforces state law. Where federal and state requirements differ, follow the more restrictive one. Certification is by category and class - private (agricultural commodity on your own/employer's land), commercial (for hire), and public agency - and a certificate only covers work in the category(ies) held.
Label anatomy
Know where to find: active ingredients, EPA registration number (product-specific) versus EPA establishment number (where it was made), signal word, precautionary statements, PPE, first aid, restricted-entry interval (REI), preharvest interval (PHI), directions for use, and storage/disposal. Oral LD50 toxicity categories: I ≤50 mg/kg (DANGER-POISON, skull and crossbones), II 50–500 (WARNING), III 500–5000 (CAUTION), IV >5000 (CAUTION).
Worker protection and records
The Worker Protection Standard applies to agricultural plants on farms, forests, nurseries, and greenhouses - not to rights-of-way or ordinary turf care. Train workers and handlers every 12 months, keep decontamination supplies within 1/4 mile, notify workers orally or by posting (in writing when the REI exceeds 48 hours), and retain application records at least two years.
Traps in questions
Confusing REI with PHI; equating a low signal word with "safe"; assuming a certificate lets you work in any category; forgetting a tank mix may not exceed the most restrictive label; ignoring drift, resistance, and endangered-species language. Rule of thumb: if the use is not on the label, it is illegal - "the label is the law."