Diseases of Maize and their management:
In this article, you will learn the various diseases of maize which causes yield loss up to 60-70 %. and we are giving their management guide. Maize is one of the important foods, forage and industrial crop of the world. It is called as ” THE QUEEN OF THR CEREALS”. Maize has the highest yield/ha among the cereal crops. it is important to control diseases of maize which are mention below as it causes yield losses.
List of diseases of maize:
1) Turcicum Leaf blight
2) Post flowering stalk rot
3) Charcoal rot
4) Banded leaf and sheath blight
1) Turcicum Leaf blight:
causal organism: Helminthosporium turcicum
Disease is characterized by long elliptical greyish-green or tan lesions on the leaves measuring 2.5 to 25 cm in length and up to 4 cm in width. The fungus affects the maize plant at a young stage. Small yellowish round to oval spots are seen on the leaves. The spots gradually increase in the area into bigger elliptical spots and are straw to greyish brown colour in the centre with dark brown margins. The spots coalesce to form bigger spots and give a blighted appearance. The surface is covered with olive green velvety masses of conidia and conidiophores. Under high humidity the whole leaf area becomes necrotic and the plant appears as dead. Lesions may be extended to the husk. This the one of major disease of maze which causes loss to crop.
The following are the management of turcicum leaf blight (diseases of maize)
- Crop rotation with other crops.
- Grow resistant hybrids like DHM-1 ¾ Treat the seeds with Captan or Thiram at 4 g/kg.
- Spray [email protected]%
2) Post flowering stalk rot:
Cephalosporium wilt (Black bundle disease and late wilt)
Causal organism: Cephalosporium acremonium/ Cephalosporium maydis
This disease of maize is caused by two organisms. which are explained further. Infection caused by C. acremonium becomes apparent when maize has reached the dough stage. One of the first symptoms is the purpling of leaves and stalks. The most characteristic symptom is the restricted blackening of vascular bundles in the stalk with the shredding of the intermodal pith region. Blackening of the vascular bundles extends through several internodes. Barren plants, excessive tillering and multiple ears are the other diagnostic symptoms.
Symptoms caused by C. maydis appear only after flowering stage and plants start wilting basipetal giving a dull green appearance of the leaves which later dry up. The lower internode turns discoloured, become reddish-brown, shrunken and soft, and subsequently becomes dry and hollow. When diseased stalks are split open, reddish-brown vascular bundles are seen.
- Crop sanitation
- Crop rotation
- Avoid water stress at flowering
- Seed treatment with Thiram or [email protected]/kg seed
- Grow resistant varieties like DHM-103, DHM 105, Hi-Starch and Ganga Safed-2.
3) Charcoal rot:
casual organism: Macrophomina phaseolina
Charcoal rot commonly attacks plants approaching maturity. The fungus produces brown, water-soaked lesions on the roots that later turn black. As the plant matures, the infection extends into the lower portions of the stem where gray streaks develop on the stem surface of lower internodes leading to premature ripening, shredding and breaking of the crown. Split open stalks have numerous black sclerotia on vascular strands, giving the interior of the stalks a charred appearance which is a characteristic symptom of the disease. Sclerotia may also be found on the roots.
- Long crop rotation with crops that are not a natural host of the fungus.
- Field sanitation ¾ Irrigate the crops at the time of earhead emergence to maturity.
- Treat the seeds with Carbendazim or Captan at 2 g/kg.
- Grow disease-resistant varieties, viz.DHM 103, DHM 105 and Ganga Safed 2.
4) Banded leaf and sheath blight:
causal organism: Rhizoctonia solani
Large, discoloured areas alternating with irregular dark bands are typical symptoms of the disease. Severe infection leads to blotching of the leaf sheath as well as leaves. The symptoms under favourable conditions extend up to silk, glumes and kernels. Disease generally appears at the pre-flowering stage. Symptoms also appear on the stalk and the internodes break at the point of infection
- Clean cultivation.
- Destruction of crop debris.
- Spray carbendazim or [email protected]%.
Sorghum downy mildew – Peronosclerospora sorghi / P. philippinensis
Crazy top downy mildew – Sclerophthora macrospora
Brown stripe downy mildew – Sclerophthora rayssiae var zeae
Sugarcane downy mildew – Peronosclerospora sacchari
Symptoms The most characteristic symptom is the development of chlorotic streaks appears on the leaves and the plants exhibit a stunted and bushy appearance due to the shortening of the internodes. White downy growth can be seen not only on the lower surface of the leaf but also on the chlorotic streaks. Affected leaves often tear linearly causing leaf shredding. The downy growth also occurs on bracts of green unopened male flowers in the tassel. The important symptom of the disease is the partial or complete malformation of the tassel into a mass of narrow, twisted leafy structures. The proliferation of axillary buds on the stalk of the tassel as well as the cobs is very common (Crazy top).
- Destruction of plant debris.
- Removal and destruction of collateral hosts.
- Grow resistant hybrids like DHM-1, DHM-103, DMR-5 and Ganaga II.
- Seed treatment with Metalaxyl (Apron 35SD) at 4g/kg.
- Deep summer ploughing ¾ Crop rotation with pulses.
- Spray the crop, 3-4 times, with Metalaxyl MZ (Ridomil MZ)@0.2% starting from 20th day after sowing.