Maize diseases and approaches to their management in India

Abstract

Abstract In India the area of land given to maize ranks fifth after rice, wheat, sorghum and pearl millet. In grain production maize holds fourth position over pearl millet. Of the 61 diseases of maize recorded so far, 15 and one nematode problem, are considered to constitute the major constraints limiting production. The major diseases are: four foliar diseases, two pre‐flowering and three post‐flowering stalk rots, four downy mildews and two sheath diseases. Information on ear, cob and kernel rots, smut and virus diseases is presented. An account of post‐harvest microbial problems is given. Four major approaches of disease management in the Indian context are outlined and the most appropriate one is considered to be host resistance. Adoption of this approach has yielded promising results for five major disease groups. It is pointed out that, so far, among the materials released which are resistant to one disease, or one set of diseases, most turn out to be susceptible to another set of diseases. The development of multiple resistance to the major diseases prevalent in the diverse agro‐ecosystems of India seems more appropriate. The population improvement approach through a recurrent selection scheme was adopted and since 1973, a high level of resistance to as many as 12 diseases has been developed. Although seven disease groups are amenable to chemical control, a very favourable cost: benefit ratio (1 : 14) is obtained only for seed and seedling groups of disease. Certain agronomic practices also help in reducing incidence of certain disease groups. The total estimate of loss in economic product per annum due to all diseases taken together has been estimated to be 13.2%.