Explore key facts on fungal diseases impacting castor plant roots and how to manage them in agricultural settings. Designed for a moderate challenge, this quiz covers major pathogens, symptoms, and control methods.
A farmer notices yellowing leaves and a brown discoloration in the vascular bundles at the base of a castor plant. Which root fungal disease is most likely responsible for these symptoms?
Explanation: Fusarium wilt is characterized by yellowing leaves and brown streaks in the vascular tissue, seen at the plant base. Powdery mildew mainly affects leaves with white spots, not the roots. Root knot nematodes cause knobby galls, not brown internal streaks. Damping-off generally affects seedlings, not mature plants showing vascular wilting.
Which method primarily spreads Macrophomina phaseolina, the fungus responsible for charcoal rot in castor plants, in agricultural fields?
Explanation: Macrophomina phaseolina persists in soil and infected crop debris, serving as the main source of infection for new plants. Airborne spread is less significant for this fungus. Insect vectors are not major carriers for this disease. Direct seed-to-seed contact is also not a primary transmission route.
Which symptom most reliably indicates Rhizoctonia root rot in castor plants?
Explanation: Rhizoctonia root rot causes sunken reddish-brown lesions at the root collar area. Leaf curling with powdery spots is typical of powdery mildew, not root rot. Swollen nodules are seen with root knot nematodes. Oozing black fluid is not characteristic of Rhizoctonia infection.
What is the most effective cultural practice for reducing the risk of root fungal diseases in castor fields?
Explanation: Crop rotation with non-host crops reduces the buildup of specific fungal pathogens in the soil. Excessive urea fertilization can worsen disease incidence. Planting during wet periods increases the risk of root disease. Spraying water alone does not prevent fungal infections.
At what stage is fungicide application typically most effective for managing soil-borne root fungi in castor crops?
Explanation: Treating seeds with fungicides before planting helps protect seedlings from early infection by soil-borne fungi. Applying fungicide after visible leaf symptoms may be too late for root protection. Treatment at harvest or during storage does not address soil-borne stages.