Crop Diseases: JAMB Agricultural Science Questions, Answers & Notes

What Crop Diseases covers in the JAMB Agricultural Science syllabus

A crop disease is any condition that disturbs a plant's normal functioning and health. Diseases are pathogenic/biotic (caused by living pathogens — fungi, which cause most tropical diseases; bacteria; viruses, e.g. cassava mosaic; and nematodes) or non-pathogenic/non-infectious (caused by non-living factors like nutrient deficiency). Symptoms include leaf spots, blights, rusts, wilting, stunting and rotting. Diseases spread by wind, water, insect vectors and infected planting material. Control methods include disease-resistant varieties (genetic), fungicides (chemical), crop rotation and field sanitation and roguing (cultural), certified clean seeds, and biological control; integrated disease management combines these. Crop diseases reduce yield, quality and income, so their control protects crops and secures food and income.

For Crop Diseases, JAMB expects you to be able to:

• Define crop disease and distinguish pathogenic (biotic) and non-pathogenic causes
• Identify pathogens (fungi, bacteria, viruses), symptoms and modes of spread
• Describe control methods and their economic importance

Key facts & revision notes: Crop Diseases

These are the recurring points our Crop Diseases questions test — revise them until each feels automatic, then practise the questions above to lock them in.

• A crop disease is any condition that disturbs the normal functioning and health of a plant.
• Pathogenic (biotic) diseases are caused by living organisms (pathogens) like fungi, bacteria and viruses.
• Crop diseases are caused by pathogens such as fungi, bacteria, viruses and nematodes.
• Non-pathogenic (non-infectious) diseases are caused by non-living factors like nutrient deficiency.
• Fungi cause the majority of crop diseases, especially in warm, humid tropical conditions.
• An infectious disease can spread from one plant to another (caused by pathogens).
• Cassava mosaic disease is a viral disease of cassava.
• Fungal diseases often show as leaf spots, blights, rusts or wilts.
• Diseases spread by wind, water, insects (vectors) and infected seeds/planting material.
• Planting disease-resistant varieties is a cultural/genetic method of disease control.
• Fungicides are chemicals used to control fungal crop diseases.
• Crop rotation breaks the life cycle of soil-borne pathogens, reducing disease build-up.
• Roguing (removing/destroying infected plants) prevents the disease from spreading to healthy plants.
• an insect) transmits pathogens from infected to healthy plants.
• Certified/clean seeds are free from pathogens, preventing the introduction of disease.
• Wilting, stunting, rotting, spots and blights are symptoms of crop diseases.
• Field sanitation (clearing crop debris and weeds) removes sources of infection, reducing disease.
• Integrated disease management combines cultural, chemical, biological and genetic (resistant varieties) methods.
• Crop diseases reduce yield, quality and income, and can cause food shortages.
• Crop disease control aims to protect crops, maintain yield and quality, and secure income.

Worked examples

Three Crop Diseases questions with the answer and a short explanation, so you can see how the topic is set before you practise the full set.

How Crop Diseases is tested in JAMB Agricultural Science

Our Crop Diseases bank holds 20 questions (11 medium, 9 hard). JAMB Agricultural Science typically returns to Crop Diseases year after year, so steady practice on this topic is high-value revision. Questions are multiple-choice with four options, and at UTME pace you get roughly 40 seconds each — which is why timed practice matters.

How to answer Crop Diseases questions

Work the stem first and predict the answer before you look at the options; then eliminate the ones that contradict the key facts above. Watch for “which is not…”, “all of the above” and “except” style stems, which are where rushed candidates lose easy marks on Crop Diseases. If a calculation or a precise definition is involved, work it from first principles rather than guessing from a half-remembered rule. When two options look right, re-read the stem for the qualifier that separates them — JAMB rarely repeats an option by accident. If you are still unsure, eliminate the two weakest choices to lift your odds, flag the question, and move on; never burn a full minute on one Agricultural Science item when the exam gives you about forty seconds each. Then come back to flagged questions with whatever time remains. The single most reliable way to get faster at Crop Diseases is repeated timed practice, so use the button above until the recurring patterns feel automatic.

Common mistakes to avoid in Crop Diseases

The errors that cost marks on Crop Diseases are usually careless rather than conceptual: misreading a negative stem, confusing two similar terms, or rushing a definition you actually know. Candidates also over-rely on “expo” and last-minute cramming instead of understanding the topic — which fails the moment JAMB rephrases a familiar idea. Treat every option as a claim to be checked against the facts above, keep your working tidy for any calculation, and don’t change a considered answer on a hunch. Above all, revise Crop Diseases actively by answering questions, not just by re-reading notes — recall under time is what the exam rewards.

Frequently asked questions

Is Crop Diseases part of the JAMB Agricultural Science syllabus?

Yes. Crop Diseases is a recognised topic in the JAMB Agricultural Science syllabus, covering define crop disease and distinguish pathogenic (biotic) and non-pathogenic causes. You should be able to recall its key facts and apply them to multiple-choice questions.

How many Crop Diseases questions can I practise on Belmadeng?

There are 20 original, JAMB-standard Crop Diseases questions in our free bank, each with the correct answer and a worked explanation. You can practise them untimed or as a timed test.

What are the most important points to know about Crop Diseases?

A crop disease is any condition that disturbs a plant's normal functioning and health. Diseases are pathogenic/biotic (caused by living pathogens — fungi, which cause most tropical diseases; bacteria; viruses, e.g. cassava mosaic; and nematodes) or non-pathogenic/non-infectious (caused by non-living…

How do I answer Crop Diseases questions quickly in JAMB?

Read the stem carefully, eliminate clearly wrong options, and match the remaining choices to the key facts for Crop Diseases. Practising timed Crop Diseases questions builds the speed you need for UTME's pace of about 40 seconds per question.

Are these JAMB Agricultural Science Crop Diseases questions past questions or original?

They are original questions written to JAMB (UTME) standard and mapped to the official syllabus — not reproduced past papers. This keeps them legal to use freely while closely mirroring how the real exam tests the topic.

Where can I practise Crop Diseases questions free without signing up?

Right here — tap “Start Crop Diseases practice” on this page to begin instantly. Belmadeng's CBT practice is completely free and needs no sign-up, download or subscription.

About these questions: original, JAMB-standard items written from the official UTME Agricultural Science syllabus (last reviewed 2026-09-18). Belmadeng is an independent study platform and is not affiliated with JAMB. Spotted an error? Use the report link.