Major Crop Diseases and Their Management MCQs 2026

Powdery mildew generally develops best under

1. Awaterlogged soil and root anaerobiosis✓
2. Bmild temperatures with high relative humidity✓
3. Cstrong frost with dry winds✓
4. Ddeep standing water in fields✓

The causal fungus of wheat stem, leaf and stripe rust belongs to the genus

1. APuccinia✓
2. BUstilago✓
3. CAlternaria✓
4. DPythium✓

Loose smut of wheat commonly becomes systemic when infection occurs during

1. Aseed drying stage✓
2. Bflowering stage✓
3. Cgrain storage stage✓
4. Dtillering stage✓

Cotton leaf curl disease is mainly spread in the field by

1. Aaphid✓
2. Bjassid✓
3. Cthrips✓
4. Dwhitefly✓

Bakanae disease of rice is characteristically associated with excessive seedling elongation due to

1. Agibberellin production by Fusarium fujikuroi✓
2. Bnitrogen toxicity in nursery soil✓
3. Czinc deficiency in flooded soil✓
4. Dbacterial ooze in vascular bundles✓

The common causal organism of rice sheath blight is

1. AMagnaporthe oryzae✓
2. BRhizoctonia solani✓
3. CXanthomonas oryzae✓
4. DUstilaginoidea virens✓

False smut of rice is recognized in the panicle by

1. Awhite powder on leaf surface✓
2. Bblack lesions on roots✓
3. Cgreenish smut balls replacing grains✓
4. Dyellow streaks on stems✓

Red rot of sugarcane is best identified in split canes by

1. Awatery soft rot at nodes✓
2. Bblack powder on leaf sheath✓
3. Csmall galls on roots✓
4. Dreddening with white transverse patches✓

The pathogen most associated with sugarcane red rot is

1. AColletotrichum falcatum✓
2. BSclerospora graminicola✓
3. CPuccinia sorghi✓
4. DPlasmodiophora brassicae✓

Whip smut of sugarcane produces a distinctive

1. Aorange powder on lower leaves✓
2. Bblack whip-like structure from the shoot apex✓
3. Cbrown ring at the collar✓
4. Dwhite cottony growth on roots✓

Citrus canker is classified as a

1. Aviral disease✓
2. Bnematode disease✓
3. Cbacterial disease✓
4. Dphysiological disorder✓

Bacterial blight of cotton is generally favored by

1. Adry hot winds only✓
2. Bfrost during boll opening✓
3. Csaline irrigation water✓
4. Dwarm humid weather and rain splash✓

Tikka disease of groundnut mainly affects the

1. Aleaves✓
2. Broots✓
3. Cflowers✓
4. Dseed embryo✓

Roguing in crop disease management means

1. Aspraying only after harvest✓
2. Bremoving diseased or off-type plants from the field✓
3. Cmixing infected seed with healthy seed✓
4. Dincreasing plant density to close gaps✓

Bordeaux mixture is prepared mainly from

1. Asulfur and kerosene✓
2. Bzinc sulfate and gypsum✓
3. Ccopper sulfate and lime✓
4. Durea and potash✓

Damping-off of nursery seedlings is usually intensified by

1. Awide spacing and dry soil✓
2. Bbalanced potassium nutrition✓
3. Cdeep summer ploughing✓
4. Dexcess moisture and poor drainage✓

Karnal bunt of wheat is primarily a disease of the

1. Agrain✓
2. Broot✓
3. Cflag leaf✓
4. Dstem node✓

Ergot disease replaces cereal grains with dark hard bodies known as

1. Auredospores✓
2. Bsclerotia✓
3. Coospores✓
4. Dconidia✓

Black scurf of potato is caused by

1. ASynchytrium endobioticum✓
2. BFusarium moniliforme✓
3. CRhizoctonia solani✓
4. DXanthomonas campestris✓

The most effective long term approach for many viral crop diseases is

1. Ahigh nitrogen application alone✓
2. Bdeep irrigation after symptom appearance✓
3. Clate sowing in every season✓
4. Dresistant varieties combined with vector management✓

A systemic fungicide commonly used as seed treatment against cereal smuts is

1. Acarboxin✓
2. Bglyphosate✓
3. Cmalathion✓
4. Dzinc phosphide✓

Downy mildew sporulation is commonly promoted by

1. Ahot dry winds and low humidity✓
2. Bsaline soil and high pH only✓
3. Ccool humid conditions and leaf wetness✓
4. Ddeficiency of phosphorus only✓

Clubroot of cruciferous vegetables is caused by

1. AAlternaria brassicae✓
2. BSclerotinia sclerotiorum✓
3. CErysiphe cichoracearum✓
4. DPlasmodiophora brassicae✓

Bacterial wilt of tomato, potato and other solanaceous crops is caused by

1. ARalstonia solanacearum✓
2. BPseudoperonospora cubensis✓
3. CTilletia indica✓
4. DUstilago tritici✓

Early blight of tomato and potato is caused by

1. APhytophthora infestans✓
2. BAlternaria solani✓
3. CFusarium udum✓
4. DPuccinia striiformis✓

Fusarium wilt pathogens often persist in soil mainly as

1. Azoospores only✓
2. Bpollen grains✓
3. Cchlamydospores✓
4. Dbacterial endospores✓

Root-knot nematode damage is commonly recognized by

1. Aorange pustules on leaves✓
2. Bblack sori in flowers✓
3. Choneydew on stems✓
4. Dgall formation on roots✓

A reliable first step to reduce seed-borne crop diseases is to use

1. Acertified disease-free seed with suitable seed treatment✓
2. Bungraded seed from infected fields✓
3. Cseed stored with high moisture✓
4. Dseed mixed across unknown sources✓

The plant disease triangle consists of

1. Asoil, fertilizer and irrigation only✓
2. Bsusceptible host, virulent pathogen and favorable environment✓
3. Cseed, pesticide and machinery only✓
4. Dtemperature, rainfall and wind only✓

The latent period of a plant disease is the time between infection and

1. Asowing of seed✓
2. Bfirst irrigation✓
3. Cproduction of new infectious propagules✓
4. Dharvesting of crop✓

Protectant fungicides give best results when applied

1. Aafter plants are completely dead✓
2. Bonly during grain storage✓
3. Conly after roots decay✓
4. Dbefore infection occurs✓

Anthracnose diseases commonly produce

1. Asunken necrotic lesions✓
2. Broot nodules with nitrogen fixation✓
3. Csilvering due to mites✓
4. Dgreen mosaic without necrosis✓

Aflatoxin contamination in groundnut and maize is mainly associated with

1. ARhizobium leguminosarum✓
2. BAspergillus flavus✓
3. CAzotobacter chroococcum✓
4. DBacillus thuringiensis✓

Common scab of potato is favored by

1. Astrongly acidic waterlogged soil✓
2. Bcontinuous flooding at tuberization✓
3. Cneutral to alkaline dry soil✓
4. Dcomplete absence of oxygen in soil✓

Wheat seed gall nematode disease is commonly called

1. Ared rot✓
2. Bwhite rust✓
3. Ckhaira disease✓
4. Dear cockle✓

Mosaic symptoms in crop plants most commonly suggest infection by a

1. Avirus✓
2. Bnematode only✓
3. Crodent pest✓
4. Dnutrient salt crystal✓

Plant quarantine primarily aims to

1. Aincrease pesticide sales in local markets✓
2. Bprevent entry and spread of exotic pests and pathogens✓
3. Creplace seed certification systems✓
4. Draise soil organic matter directly✓

Hot water treatment of seed is used to

1. Aincrease seed moisture for storage✓
2. Bconvert hybrid seed into pure lines✓
3. Celiminate certain seed-borne pathogens under controlled temperature✓
4. Dreplace all field sanitation measures✓

Collar rot and stem rot caused by soil-borne fungi are often encouraged by

1. Acomplete absence of organic residues✓
2. Bvery wide crop rotation only✓
3. Cdry sterile seedbeds only✓
4. Dwarm moist soil and infected plant debris✓

A physiological race of a pathogen is best described as a strain differing in

1. Avirulence on host differential varieties✓
2. Bshape of farm machinery required✓
3. Camount of fertilizer needed by crop✓
4. Dmethod of grain threshing✓

Horizontal resistance in crops is generally

1. Acontrolled by one major gene only✓
2. Bpolygenic, partial and relatively durable✓
3. Ceffective against insects only✓
4. Da symptom of nutrient toxicity✓

The classic alternate host of wheat stem rust is

1. Aberseem✓
2. Bsunflower✓
3. Cbarberry✓
4. Dsorghum✓

Smut fungi commonly produce dark masses of

1. Aascospores only✓
2. Bzoospores only✓
3. Cconidiophores only✓
4. Dteliospores✓

Angular leaf spots with bacterial ooze most strongly indicate a

1. Abacterial disease✓
2. Bviral deficiency complex✓
3. Cnematode cyst disease✓
4. Dstorage insect injury✓

Soil solarization helps manage soil-borne diseases by

1. Acooling soil below freezing point✓
2. Btrapping solar heat under transparent polyethylene✓
3. Cadding nitrogen directly from sunlight✓
4. Dblocking all oxygen permanently✓

Crop rotation is least effective against pathogens that

1. Asurvive only on one short-season crop✓
2. Black any resting structures✓
3. Chave wide host range and long-lived survival structures✓
4. Ddie immediately after harvest✓

Late blight management in potato relies heavily on

1. Alate harvesting without field scouting✓
2. Bexcess nitrogen and overhead irrigation✓
3. Cuse of visibly infected seed tubers✓
4. Dsanitation, resistant varieties and timely fungicide sprays✓

Stripe rust of wheat is favored mainly by

1. Acool humid weather✓
2. Bvery hot dry winds✓
3. Csaline irrigation alone✓
4. Ddeep flooding for weeks✓

Integrated disease management means

1. Ausing one pesticide repeatedly every week✓
2. Bcombining compatible methods based on disease ecology✓
3. Cignoring host resistance in all crops✓
4. Dcontrolling only weeds after harvest✓