Disease management

Across the country several diseases occurs during different seasons, if they are not managed at proper time than they leads to yield loss. Estimated losses due to major diseases of maize in India is about 13.2% of which foliar diseases (5 %), stalk rots, root rots, ear rots (5 %) cause major yield losses. The major diseases and their management practices are described as below:

i. Turcicum leaf blight (TLB)

This disease is distributed in Jammu & Kashmir, Himachal Pradesh, Sikkim, West Bengal, Meghalaya, Tripura, Assam, Uttar Pradesh, Uttarakhand, Bihar, Madhya Pradesh, Gujarat, Karnataka and Tamil Nadu. At its appearance, it shows long, elliptical, grayish-green or tan lesions ranging from 2.5 to 15 cm in length on the leaves. For control of TLB, spray Zineb/Meneb @ 2.5-4.0 g/liter of water (2- 4 applications) at 8-10 days interval. The crop debris should be ploughed down. Also, the resistant cultivars should be grown.

ii. Maydis leaf blight (MLB)

MLB also occurs in wide range of maize growing states like Jammu & Kashmir, Himachal Pradesh, Sikkim, Meghalaya, Punjab, Haryana, Rajasthan, Delhi, Uttar Pradesh, Bihar, Madhya Pradesh, Gujarat, Maharashtra, Andhra Pradesh, Karnataka & Tamil Nadu. It shows the symptoms as lesions on the leaves elongated between the veins, tan, 2-6 x 3-22 mm with limited margins with buff to brown borders. For effective control of this disease, spray of Dithane Z-75 or Zineb @ 2.4 - 4.0 g/liter of water (2-4 applications) at 8-10 days interval after first appearance of symptoms of disease. In addition, the crop debris should be ploughed down. Also, the resistant cultivars should be grown.

iii. Polysora Rust

This disease appears mainly in peninsular India i.e Andhra Pradesh, Karnataka and Tamil Nadu. The main symptoms of the disease shows appearance of circular to elongate light cinnamon brown, circular to oval 0.2-2.0 mm long densely scattered legions on the upper leaf. The uredospores are yellowish to golden in colour. For effective control of polysora rust, three sprays of Dithane M-45 @ 2-2.5 gm/liter beginning from first appearance of symptoms at 15 days interval are required. It is always advisable to use resistant varieties.

iv. Banded leaf and sheath blight (BLSB)

This disease mainly occurs in Jammu and Kashmir, Himachal Pradesh, Sikkim, Punjab, Haryana, Rajasthan, Madhya Pradesh, Delhi, Uttar Pradesh and Bihar. At appearance of the disease, white lesions develops on leaves and sheath. Purplish or brown horizontal bands present on white lesions characterize the disease. Seed treatment with peat based formulation (Pseudomonas fluorescence) @ 16 g/kg of seed or as soil application @ 7g/liter of water (soil drenching) or foliar spray of Sheethmar (Validamycin) @ 2.7 ml /liter water provides effective control of the disease. Stripping of 2 lower leaves along with leaf sheath also gives effective control of the disease.

v. Post Flowering Stalk Rot of Maize (PFSR)

The PFSR occurs mainly in Rajasthan, Uttar Pradesh, Bihar and Andhra Pradesh. Disease appears when the crop enters in senescence phase. The pathogen commonly affects the roots crown regions and lower internodes. When split open, the stalk shows pink-purple dis-colouration. For effective control of the disease, water stress at flowering should be avoided. Use balance dose of nutrients wherein potassium application helps in minimizing the disease. Use of bio-control agents (Trichoderma formulation) in furrows mixed with FYM @ 10g/kg at 10 days prior to its use in the field. It always advisable to practice crop rotation to minimize the disease incidence.

vi. Downy mildews (DM)

Himachal Pradesh, Sikkim, West Bengal, Meghalaya, Punjab, Haryana, Rajasthan, Delhi, Uttar Pradesh, Bihar, Madhya Pradesh and Gujarat are prone to downy mildews. The main symptoms of downy mildew are legends developing on lower leaves as narrow chlorosis strips. Strips extend in parallel fashion, well defined margined delimited by veins. Downy whitish to creamy growth usually on the ventral surface of the infected leaves appears corresponding to stripes. For control of downy mildew, the infected plants should be rogue out and destroyed. The planting of crop before onset of rains minimizes the incidence of mildew. Seed treatment with fungicides like Apron 35 WS @ 2.5 g/kg seed. Also the resistant varieties should be used.