Management of Sugarbeet Diseases

Abstract

The diseases of the sugarbeet (Beta vulgaris L) are one of the major constraints in the profitable commercial cultivation of crops in the country. Under Indian conditions, about 10–15% of the crop is destroyed by the diseases. Out of 25 diseases known in the country, about 15 are economically important. Among the diseases caused by fungi, seed/seedling disorders, foliar diseases, root rots of adult plants and nematodes both in root and seed crop are more destructive. Fortunately, the extent of damage caused by bacteria and viruses is negligible. Seedling afflictions also known as damping-off, black leg, seedling blight, seedling root rot, collar rot are of great importance. Both pre- and post-emergence mortality destroying 15–30% seeds/seedlings are observed. The pathogens envolved are Phoma betae, Pythium spp., Sclerotium rolfsii, Rhizoctonia solani, R. bataticola, Fusarium spp. and Alternaria spp. Seed/Seedling diseases can be effectively managed by conventional seed treatment with fungicides, seed polishing and seed pelleting with mixture of two fungicides or incroportion of bio-agents. Among foliar diseases, Cercospora leaf spot (Cercospora beticola) is a major disease of root crops in plains reducing both root yield and sugar production by 33% and 44%, respectively. Alternaria leaf spot (Alternaria alternata, A. brassicae) also damages up to 30% leaf area. Powdery mildew (Erysiphe betae) is a disease of warm and dry weather and reduces the root yield by 20–25%. These can be managed by spraying of fungicides like Benlate, Bavistin, Thiabendazol, wetable sulphur, Dithane M-45 and Dithane Z-78. Adult sugarbeet roots are affected by a number of soil borne diseases. Sclerotial root rot (Sclerotium rolfsii) is the most destructive disease causing about 50% damage of roots. Other diseases are dry root rot (Rhizoctonia solani) and charcoal root rot (R. bataticola) causing 15–30% damage of roots. Affected roots from these diseases are unfit for sugar extraction. These diseases can be managed by soil drenching of fungicides like PCNB, Bavistin Vitavax and Thiram and by manipulation of cultural practices. Biological agents like Gliocladium virens, Trichoderma harzianum and T. viride have been found effective in reducing root rots.KeywordsPowdery MildewRhizoctonia SolaniTrichoderma HarzianumRoot YieldCercospora Leaf SpotThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.