Disease and Insect Pest Management in Maize
Maize is one of the most important grain crops in the world. The main season of maize cultivation is rainy season and hence prone to many diseases and pests. The management of important disease and pests are briefly discussed below.
A. Disease management:
(i) Downy mildew (DM): In India, DM is caused by Peronosclerospora sorghi and popularly known as sorghum downy mildew. Downy mildew appearing in the Rajasthan state is caused by a variant of P. sorghi and designated as Rajasthan downy mildew. Both forms of DMs cause heavy yield loss. Seed treatment with Metalaxyl W.P. @ 4g/kg of seeds and foliar spray of Mancozeb 2.5 g/l or Metalaxyl MZ at 2g/l provides excellent control over the disease.
(ii) Turcicum leaf blight (TLB): This is one of the most important diseases in Northern and North-eastern hills and peninsular India and is caused by Exserohilum turcicum. If not controlled at proper time, it has the potential to cause yield reduction up to 70%. Two to four applications of Maneb or Zineb @ 2.5-4.0 gm/litre of water at 7-10 days interval provide good control of the disease.
(iii) Maydis leaf blight (MLB): MLB is caused by Bipolaris maydis and generally appears in warm tropical and sub-tropical areas to wet temperate climate. It has the potential to cause as high as 70% yield loss. Application of 2-4 sprays of Diathane M-45 or Zineb @ 2.0-2.5 gm/litre of water at 7-10 days interval from the first appearance of disease controls the spread of pathogen.
(iv) Polysora rust (PR): Polysora rust or Southern rust caused by Puccinia polysora is prevalent in Penninsular India and can cause substantial damage. Spray of Diathane M-45 @2-2.5 gm/litre at the beginning of appearance of symptoms provides good control. However, additional 1-2 sprays may be provided depending upon the intensity of infestation.
(v) Post flowering stalk rot (PFSR): PFSR is prevalent mainly in Rajasthan, UP, Bihar and AP; although it may appear in other maize growing areas in North and South India. It is one of the most destructive diseases and is caused by complex association of multiple pathogens, among which Fusarium moniliforme, Macrophomina phaseolina and Cephalosporium maydisare commonly associated.The symptoms start appearing during senescence and it commonly affects roots, crown region and lower internodes. Application of potassium fertilizer minimizes the incidence of disease. Avoidance of water stress at flowering stage and crop rotation also reduces the incidence of the disease to a great extent. Further, application of bio-control agent such as Trichoderma formulation in furrow @ 10g/kg of FYM at 10 days prior to sowing provides good control.
(vi)Banded leaf and sheath blight (BLSB): BLSB caused by Rhizoctonia solani f. sp. sasakii has recently emerged as an important disease in Asia and South East Asia and can cause substantial loss to grain yield and fodder quality. The disease is very difficult to control. Removing lower 2-3 leaves, application of Pseudomonas fluorescens culture @16g/kg of seeds (as seed treatment) or 7g/litre of water for soil application coupled with foliar spray of Sheethmar or Validamycin @ 2.5-3.0 ml/litre of water provides reasonable control on the spread of the disease.
(i)Stem borer: Stem borer or Chilo partellus is a major insect pest in India and infest maize crop during the kharif season all over India. Spray of Cholopyriphos @ 1-1.5ml/litre of water at 10-12 days after germination provides good control. The insecticide should be mixed in 800- 1000 litre of water and evenly sprayed over the canopy per hectare. Additional 1-2 sprays after 7-10 days intervals further restricts the insect infestation. Alternatively, application of Carbofuron G 3% @ 0.6 kg a.i. / ha in the leaf whorls after 15-20 days after germination, provides protection against stem borer.
(ii)Pink borer: Pink borer or Sesamia inference affects maize crop during the rabi season and mainly restricted to Peninsular India. The larvae enter the plant at base by making a hole and damages the inside portion of the stem. This makes the plant stem weak and mild to heavy wind leads to the falling of the plants. The control measure is similar to stem borer as mentioned above.
(iii)Shoot fly: Shoot fly (Atherigona sp.) is a serious pest in Peninsular India, but can affect summer or spring crop in North Indian states as well. It affects the maize plants at the seedling stage and leads to drying of the seedlings or ‘dead heart’. Seed treatment with Imidacloprid @ 6ml/kg of seeds provides good control of the shoot fly. Early sowing during first fortnight of February avoids build up of shoot fly population.
(iv)Termites: Termite (Odontotermes obesus)isa major problem in the some fields. If not controlled, it can cause substantial damage to the maize crop. Since they establish colonies much deep into the soil, it is very difficult to get rid of the problem completely. Frequent irrigation before land preparation and during the crop growth reduces its infestation. Application of Fepronil granules @ 20kg/ha followed by light irrigation controls termites to a reasonable extent. If the infestation occurs in patches, applying few granules of Fepronil on and around the patches control termite infestation.
Submitted by jsbhat on Fri, 03/05/2013 - 01:01