Dive into essential strategies for protecting onion crops from common pests, diseases, and environmental threats in horticulture. Assess your knowledge of integrated management practices that ensure healthy onion yields.
Which insect pest is most commonly associated with causing direct damage to onion bulbs by laying eggs at the base, leading to maggots feeding on the roots?
Explanation: The onion fly lays its eggs near the base of onion plants, and its maggots feed on underground parts causing significant bulb damage. Aphids and thrips attack above ground and primarily sap nutrients without directly harming bulbs. Cutworms can damage seedlings but are less specific to bulbs and their feeding occurs above the soil.
What is the most effective cultural practice to prevent the spread of Fusarium basal rot in onion fields?
Explanation: Crop rotation reduces disease buildup in soil by interrupting the pathogen's life cycle, making it the best practice for Fusarium control. Overhead irrigation can increase fungal spread, high nitrogen promotes soft tissue susceptible to rot, and deeper planting increases vulnerability to soil pathogens.
If a grower observes silver streaks and distorted leaves on onions, which IPM (Integrated Pest Management) strategy is recommended for thrips management?
Explanation: Reflective mulches repel thrips and reduce their population on onions, forming a physical deterrent. Deep watering is not effective against thrips. Urea spray may promote green growth but doesn't address pests. Late planting may increase exposure to thrips if their population peaks later.
Which precaution is vital to prevent onion crop injury when using herbicides for weed control?
Explanation: Applying herbicides at the correct onion growth stage minimizes the risk of crop injury. Random mixtures, higher doses, or spraying in heat increase the risk of phytotoxicity and are not recommended.
What post-harvest handling practice best reduces the risk of bacterial soft rot in stored onions?
Explanation: Curing allows outer layers to dry and creates a protective barrier against bacteria, reducing soft rot incidents. Washing can introduce excess moisture, high humidity promotes bacterial growth, and immediate packing without curing increases decay risk.