Waec Model Questions Vol1 2023 Agricultural Science Question 8

Practice essay / theory question 8 from the 2023 Waec Model Questions Vol1 Agricultural Science examination. This question covers Plant Diseases, Disease Incidence, Severity Index, Control Measures, Yield Loss Estimation .

Waec Model Questions Vol1 2023 Agricultural Science Essay / Theory
Topics: Plant Diseases Disease Incidence Severity Index Control Measures Yield Loss Estimation
Question 8 WAEC_MODEL_QUESTIONS_VOL1 • 2023 • AGRICULTURAL_SCIENCE • essay

During a routine scouting of a 5‑ha maize field in the Middle Belt, a farmer observed leaf lesions that were elongated, grey‑green and surrounded by a yellow halo. A sample of 200 plants was examined, and 30 plants showed typical symptoms of the disease. Of the symptomatic plants, 10 exhibited mild lesions covering less than 25 % of the leaf area, while the remaining 20 showed severe lesions covering more than 50 % of the leaf area.

Question Parts

( a )
State the most likely disease and the causal pathogen.
( b )
Calculate the disease incidence (%) and the disease severity index (expressed as a percentage, rounded to one decimal place). Use a severity rating of 1 for mild lesions and 3 for severe lesions.
( c )
Recommend an integrated control strategy for this disease, mentioning at least one cultural, one chemical and one resistant‑variety measure, and justify each choice.
( d )
If the potential yield of the field is 5 t ha⁻¹ and each percent of disease incidence reduces yield by 0.8 % of the potential yield, estimate the expected yield loss (in kilograms per hectare) caused by the disease.

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About This Question

This is Waec Model Questions Vol1 2023 Agricultural Science Question 8. It is one of the essay questions from the 2023 Waec Model Questions Vol1 Agricultural Science examination.

The question covers Plant Diseases, Disease Incidence, Severity Index, Control Measures, Yield Loss Estimation .

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