Globally, maize is known as ‘Queen of the Cereals’ or ‘Miracle C4 crop’ because of its genetic makeup conserves highest yield potentiality among the other cereals and gaining popularity as evidenced by its large-scale consumption as food (61%), feed (17%), fodder for animals and as source of industrial raw materials (22%) viz., starch, syrup, dextrose, gelatin, protein, alcoholic beverages, oil, pharmacy, cosmetics, bio-fuel (ethanol), food sweeteners, etc.
Maize has a distinctive adaptability feature to cultivate different session (Kharif, Rabi and spring) throughout the year in one or other locations of the countries. The major maize growing states that contribute to maize production are Madhya Pradesh, Karnataka, Maharashtra, Rajasthan, Uttar Pradesh, Bihar, Gujarat, Tamil Nadu, Jammu Kashmir, and others. The major diseases prevalent in different agro-climatic zones of India are leaf spot, seed rot and seedling blight, banded leaf and sheath blight, downy mildew, stalk rot, smut and rusts.
Banded leaf and sheath blight (BLSB)
Causal organism: Rhizoctonia solani f. sp. sasakii
Description
The disease is reported to occur in Jammu Kashmir, Himachal Pradesh, Uttrakhand, Sikkim, Meghalaya, Assam, Nagaland, Punjab, Haryana, Rajasthan, Madhya Pradesh, Delhi, Uttar Pradesh and Bihar the disease is prevalent in hot humid foothill region of Himalayas and in plain. In Haryana, the disease is occurring in moderate to severe form since last couple of years and causes yield losses.
Symptoms:
The disease appears on leaves and sheath on 40-45 days old plant and later on spread to the ear. The characteristic lesions appear as concentric bands and rings on lower leaves and sheath. The affective plant produces large, grey, tars or brown discolor areas alternating with dark brown bands. Later on sclerotia are formed in these areas. The developing ear is completely damaged and dried up pre-maturely with cracking of the husk leaves. Brown rotting of ear also develops which shows conspicuous light brown cottony mold with small, round block sclerotia.
Management
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Stripping of lower 2-3 leaves along with their sheath considerable reduces the disease incidence.
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Use of resistant/tolerant hybrids
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Application of validamycine, carbendazim (0.2%) and moncren (0.1%) were found effective in checking the disease.
Maydis leaf blight (MLB)
Causal organism: Bipolaris maydis
Description
This disease occurs in major part of India which includes states of Jammu Kashmir, Himachal Pradesh, Sikkim, Meghalaya, Punjab, Haryana, Rajasthan, Delhi, Uttar Pradesh, Bihar, Madhya Pradesh, Gujarat, Maharashtra, Andhra Pradesh, Karnataka and Tamil Nadu. The disease is distributed in warm humid temperate to tropical where the temperature ranges from 20 – 30o C during cropping period.
Symptoms
The disease can be manifested by the appearance of numerous dead brown or purplish areas surrounded by a reddish brown margin on the leaves and the lesions longitudinally elongated, often coalescing to form more extensive dead portions.
Management
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Sanitation and destruction of crop debris will reduce the initial amount of inoculums.
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Rotation with non host species.
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Spraying of crop with mancozeb (0.2%) with the appearance of the disease at ten days interval found effective in controlling the disease.
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Growing resistant hybrids/varieties.
Common rust
Causal organism: Puccinia sorghi
Description
The disease is prevalent in subtropical, temperate and high land environment. The disease is reported in Jammu Kashmir, Himachal Pradesh, Sikkim, Meghalya, West Bengal, Punjab, Haryana, Rajasthan, Uttar Pradesh, Bihar, Madhya Pradesh, Maharashtra, Andhra Pradesh, Karnataka and Tamil Nadu.
Symptoms
Disease appearance is common at the time of teaseling. Common rust is recognized by the appearance of circular to elongate brown powdery pustules scattered over both surfaces of the leaf. Their powdery nature is due to the masses of uredospores that break through the epidermis of the leaf. As corn matures, black pustules are formed on the both surfaces of the leaves because of formation of black teliospores in place of brown uredospores.
Management
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Grow resistant /tolerant hybrids.
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Foliar spray with mancozeb @ 0.2 to 0.25 % at ten days interval starting with the appearance of the disease was found effective in checking the disease.
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Cultivate early maturing varieties
Bacterial stalk rot
Causal organism: Dickeya zeae
Description
The disease occurs in many states like Sikkim, West Bengal, Himachal Pardesh, Punjab, Haryana, Rajasthan, Delhi, Uttar Pardesh, Uttarkahand, Bihar, Madhya Pardesh and Andhra Pradesh. The high incident of this disease is favoured by high temperature (32-35ºC) and high relative humidity.
Symptoms
Disease can infect the plant at any node from the soil surface upto whole plant. Primary symptoms of discolouration due to tan to dark brown, water soaked slimy lesion on the leaf sheath and stalk appear when plants suddenly falls over and are seen scattered in the field. During advance stage of infection, a foul order can be sensed from the macerated tissues and the top of such plants can be easily removed from the rest of plant. Disease plants may remain green several days.
Management
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To manage the disease destroys the diseased plant debris.
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Keep the fields well drained and ensure proper drainage to avoid water logging.
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Maintain required plant population and planting of crop on ridges rather than flat sowing
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Application of 150 gm of Captan and 33gm of stable bleaching powder in 100 liters of water and drench the soil near plant roots when crop is 5-7 weeks old is effective in checking the disease.
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Uproot and destroyed infected plant when crop reaches 5-7 weeks.
Fusarium stalk rot
Causal organism: Fusarium verticillioides
Description
The disease occurs in Rajasthan, Uttar Pradesh, Haryana, Bihar and Andhra Pradesh
Symptoms
Symptom becomes conspicuous when the crop enters senescence phase. Infected plants leaves turn to dull green instead of dark green color and the lower stalk become yellow/ straw colour and whole plant is wilted. The internal pith of the lower nodes get disintegrated and softened which can be easily pressed between thumb and finger. Fungal mycelium can often be seen at such nodes. The pathogen commonly affects the roots crown regions and lower internodes. When split open, the stalk shows pink-purple discoloration.
Management
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Deep ploughing, sanitation and removal of previous crop debris.
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Always maintained recommended plant population.
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Balanced soil fertility, avoid high level of N and low level of K
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Use crop rotation with non host crop like soybean.
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Use the resistant or disease tolerant Hybrids
Pythium stalk rot
Causal organism: Pythium aphanidermatum
Description
The disease occurs in Sikkim, Himachal Pradesh, West Bengal, Punjab, Rajasthan, Uttar Pradesh and Bihar.
Symptoms
Disease may occur prior to flowering and is usually confined to the first or second internode above the soil line with the roots and top of the plant becoming infected. The outer rind and pith tissues are rotted with only the vascular bundles remain intact. The cottony growth can be seen on the infected portion of the plant. The diseased area of the stalk becomes brown, water soaked, soft and the stalk is collapsed.
Management
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To manage the disease destroys the diseased plant debris.
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Keep the fields well drained to avoid water logging that helps in zoospore dispersal.
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Maintain required plant population.
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Use resistant varieties/hybrids
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Application of 150g of captan and 33g of stable bleaching powder in 100 liters of water and drench the soil near plant roots when crop is 5-7 weeks old is effective in checking the disease.
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Uproot and destroyed infected plant when crop reaches 5-7 weeks
Charcoal Rot
Causal Organism: Macrophomina phaseolina
Description
The disease occurs in Jammu Kashmir, West Bengal, Punjab, Haryana, Rajasthan, Delhi, Uttar Pradesh, Madhya Pradesh, Andhra Pradesh, Karnataka and Tamil Nadu.
Symptoms
Disease appears one to two weeks after the flowering. This disease is prevalent in comparatively dried maize growing areas. The diseases are usually conformed to first or second internode above soil level. Disease also becomes apparent as the plant approach maturity. Affected plants dry premature and the affected internodes become disintegrated and show black discoloration. Presence of numerous, minute black sclerotia on vascular bundles and inside the rind of the stalks is a distinguished character. Water stress at or after flowering has been found to pre dispose the plant to infection.
Management
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Deep ploughing, sanitation and removal of previous crop debris from soil.
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Use crop rotation, avoiding water stress at flowering time to reduce disease incidence.
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Use resistance varieties/hybrids.
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In affected field, balance soil fertility specially increases the potash level up to 80 kg/ha.
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Use of Trichoderma formulation after mixing with FYM @ 10 g/kg and incubate for 10 days covered with wet gunny begs helps in reducing the disease. This mixture should be used in furrows before sowing.
Curvularia leaf spot
Causal Organism: Curvularia lunata
Description
The disease is prevalent in hot and humid areas.
Symptoms
Initial symptoms of the disease include small necrotic spots with a light colored halo. Lesions are about 0.5 cm in diameter when fully developed. Severe infection can cause yellow of whole leaf.
Management
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Deep ploughing, sanitation and removal of previous crop debris from soil.
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Use crop rotation, avoiding water stress at flowering time to reduce disease incidence.
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Use resistance varieties/hybrids.
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Seed Treatment with 20 g Trichoderma chalk formulation + Mancozeb 63% or Thiram 40 F.S. @ 6 g/kg seed.
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Foliar Spray: – It should be done at 35 and 55 DAS using Carbendazim 12%+ Mancozeb 62% or Zineb 75% @ 2 g/lit of solution.
Authors
Parvesh Kumar1 and Poonam Kumari
Department of Plant Pathology,
Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana, India 125004
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