Explore key concepts of thrips management in onion cultivation, covering identification, control methods, and crop protection strategies. This quiz challenges your knowledge of best practices for handling thrips in agriculture.
Which visible symptom on onion leaves most likely indicates an infestation of thrips?
Explanation: Silvery streaks and curling leaves are typical of thrips feeding, as these insects scrape the leaf surface. Wilting with black mold usually points to fungal infection, not thrips. Brown, sunken lesions are more characteristic of bacterial or fungal diseases. Leaf tip yellowing can result from nutrient deficiencies.
At which stage in their life cycle are onion thrips most effectively controlled by contact insecticides?
Explanation: Contact insecticides are most effective against mobile, exposed thrips larvae. Eggs are protected within leaf tissue, while soil-dwelling pupae are less accessible, and adults may avoid treated surfaces due to their mobility.
Which cultural practice best helps reduce thrips populations in onion fields?
Explanation: Reflective mulches can deter thrips by altering light and making it harder for them to locate onion plants. Watering at midday can stress plants, excessive nitrogen may attract more pests, and harsh pruning can damage onions without managing thrips.
Which beneficial insect is commonly used to biologically control thrips in onions?
Explanation: Minute pirate bugs are effective thrips predators. Lady beetles prefer aphids, praying mantises are generalists and fewer in number, and while green lacewing larvae eat thrips, they are best known for controlling aphids.
What is an important strategy to prevent thrips developing resistance to insecticides?
Explanation: Rotating chemicals with different modes of action reduces selection pressure and helps delay resistance. Relying on the same insecticide, using higher doses, or timing applications solely for weather do not address the core issue of resistance development.