Weed Biology and Control - Revision Sheet

1. 📌 Essentials

• Weeds: Unwanted plants competing with crops, with adaptive reproductive strategies.
• Major weed families: Poaceae, Cyperaceae, Asteraceae (>50% of significant weeds).
• Reproductive: Gemenative (vegetative), parasitic, agamospermy.
• Seed dormancy: Seeds may remain dormant post-ripening, especially parimanna dormancy.
• Abiotic factors: Temperature and soil moisture critically influence weed emergence.
• Seed bank: Most seeds are located within 10-20 cm soil depth.
• Control methods: Flame weeding can induce dormancy; cultivation depth affects seed bank management.
• Growth forms: Erect, prostrate, climbing, bushy, perennial, annual.
• Weed phenology: Varies seasonally; e.g., Raphanus raphanistrum (winter-spring), Avena fatua (summer).
• Seed dispersal: Mainly via fruit capsules or pods.
• Parasitic weeds: Require host plants (e.g., Cuscuta, Onobanche).
• Preventive measures: Delay or inhibit weed establishment in uninfested areas.

2. 🧩 Key Structures & Components