Plant Diseases Practice Questions
18 free Plant Diseases practice questions for the General Science. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
What is the most common cause of plant diseases?
- A Fungi
- B Bacteria
- C Viruses
- D Algae
Correct answer: Fungi
Fungi are responsible for the majority of plant diseases worldwide. They infect plants by penetrating tissues and absorbing nutrients, often causing visible symptoms such as spots, rots, or wilting.
Which plant disease is caused by the fungus Puccinia?
- A Rust disease
- B Blight disease
- C Wilt disease
- D Smut disease
Correct answer: Rust disease
Rust diseases are caused by fungi belonging to the genus Puccinia. They produce characteristic reddish-brown pustules on leaves and stems.
Which bacterium causes citrus canker?
- A Xanthomonas citri
- B Agrobacterium tumefaciens
- C Bacillus subtilis
- D Pseudomonas aeruginosa
Correct answer: Xanthomonas citri
Citrus canker is caused by the bacterium Xanthomonas citri. It produces lesions on leaves, stems, and fruits of citrus plants, reducing crop yield.
Which plant disease caused the Irish potato famine in the 19th century?
- A Late blight
- B Powdery mildew
- C Rust
- D Leaf spot
Correct answer: Late blight
Late blight of potato, caused by the pathogen Phytophthora infestans, led to the Irish potato famine. It destroys leaves and tubers rapidly under moist conditions.
Mosaic diseases in many plants are caused by which group of pathogens?
- A Fungi
- B Bacteria
- C Nematodes
- D Viruses
Correct answer: Viruses
Mosaic diseases are caused by plant viruses, such as tobacco mosaic virus. They produce mottled or mosaic-like patterns on the leaves.
Which disease affects wheat and is caused by the fungus Puccinia graminis?
- A Wheat rust
- B Wheat blight
- C Wheat wilt
- D Wheat mosaic
Correct answer: Wheat rust
Wheat rust is a fungal disease caused by Puccinia species. It produces rust-colored spores that damage leaves and reduce crop productivity.
Which plant disease is caused by the bacterium Agrobacterium tumefaciens?
- A Crown gall disease
- B Bacterial leaf blight
- C Powdery mildew
- D Rust disease
Correct answer: Crown gall disease
Crown gall disease results from infection by Agrobacterium tumefaciens. The bacterium causes tumor-like growths at the crown of plants.
Which type of organism causes plant diseases such as root-knot disease?
- A Virus
- B Bacterium
- C Fungus
- D Nematode
Correct answer: Nematode
Root-knot diseases are caused by nematodes, microscopic roundworms living in soil. They cause swelling and knots in plant roots, affecting nutrient absorption.
Which environmental condition commonly favors the spread of fungal plant diseases?
- A Dry and windy weather
- B High humidity
- C Cold nights
- D Strong sunlight
Correct answer: High humidity
High humidity and moisture create favorable conditions for fungal spores to germinate and infect plants. Many fungal diseases spread rapidly during rainy seasons.
Which plant disease affects rice and causes significant crop loss in Asia?
- A Rice blast
- B Rice rust
- C Rice wilt
- D Rice mosaic
Correct answer: Rice blast
Rice blast is a serious fungal disease caused by Magnaporthe oryzae. It affects leaves, stems, and grains, leading to major agricultural losses.
Which term refers to the yellowing of plant leaves due to disease?
- A Chlorosis
- B Necrosis
- C Wilting
- D Leaf blight
Correct answer: Chlorosis
Chlorosis occurs when leaves lose chlorophyll and turn yellow. It may result from nutrient deficiency or infection by pathogens.
Which plant disease symptom involves the death of plant tissue?
- A Chlorosis
- B Necrosis
- C Wilting
- D Mosaic
Correct answer: Necrosis
Necrosis refers to the death of plant cells or tissues. It often appears as brown or black dead patches on leaves or stems.
Which disease of sugarcane is caused by a virus?
- A Red rot
- B Mosaic disease
- C Rust disease
- D Whip smut disease
Correct answer: Mosaic disease
Sugarcane mosaic disease is caused by a virus that produces mosaic-like discoloration on leaves. This infection reduces the efficiency of photosynthesis.
Which agricultural practice helps prevent the spread of plant diseases?
- A Crop rotation
- B Overwatering
- C Monoculture farming
- D Excess fertilizer use
Correct answer: Crop rotation
Crop rotation disrupts the life cycle of many plant pathogens. By planting different crops each season, farmers reduce disease buildup in the soil.
Which disease symptom involves the drooping of plant leaves due to loss of water pressure?
- A Necrosis
- B Chlorosis
- C Blight
- D Wilting
Correct answer: Wilting
Wilting occurs when plants lose water faster than it can be replaced. It may result from pathogen infection blocking water transport.
Which fungal disease of grapevines is caused by Erysiphe necator and badly reduces berry quality?
- A Downy mildew
- B Anthracnose
- C Black rot disease
- D Powdery mildew
Correct answer: Powdery mildew
Grape powdery mildew is caused by the fungus Erysiphe necator. It coats leaves and berries with a whitish floury growth, and infected berries crack and ripen poorly, lowering both yield and quality.
Which plant disease causes black lesions on leaves and fruits of apple trees?
- A Apple rust
- B Apple wilt
- C Apple mosaic
- D Apple scab
Correct answer: Apple scab
Apple scab is a fungal disease caused by Venturia inaequalis. It produces dark, scabby lesions on leaves and fruits.
Which method is commonly used to control fungal plant diseases?
- A Insecticides
- B Herbicides
- C Rodenticides
- D Fungicides
Correct answer: Fungicides
Fungicides are chemicals designed to prevent or kill fungal pathogens. They are widely used in agriculture to control fungal plant diseases.