Full explanation
Pre-emergence herbicides work via a soil screen: they form a film in the top 0–3 cm that kills weeds as they germinate. Efficacy depends on soil moisture — on dry fields it drops 40–60%. Key products in Ukraine: Prowl (pendimethalin, BASF), Dual Gold (S-metolachlor, Syngenta), Stomp (pendimethalin, BASF), Racer (flurochloridone, Syngenta), Frontier (dimethenamid, BASF), Mistral (metribuzin, multiple). Typical dose 1.5–4 L/ha, treatment cost UAH 500–1,400/ha. Applied within 1–3 days after sowing, mandatorily onto moist soil (10+ mm rain within ±7 days). Advantages: lower crop-injury risk, 6–8 week residual control. Limitations: weak on perennials, requires predictable weather.