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ThesisItem Open Access Investigations on Alternaria leaf spot of cauliflower caused by Alternaria brassicicola (Schwein.) Wiltshire and its management(2024-02-25) Mukesh Kumar; Dr Ved RatanCauliflower is one of the most important cole crops which are grown almost throughout the year for its economic and nutritional value. India occupies second position in cauliflower production worldwide. Nowadays, the production of cole crops declined due to fungal, bacterial and viral diseases. The major fungal diseases including alternaria leaf spot inciting by Alternaria brassicicola, of cauliflower causes enormous losses in cole crops. This pathogen has been reported from all over the including Uttar Pradesh, India.The severity of the disease appeared in wet season and relatively high rainfall areas.Based upon seriousness of disease our investigation was carried on various aspects viz; survey and collection of disease sample, isolation and purification of associated pathogen, environmental factors on disease development, cultural media studies and evaluation of several bioagents, botanicals and chemical fungicides against alternaria brassicicola at Department of Plant Pathology and Student Instructional Farm (SIF) at Chandra Shekhar Azad Agriculture University and Technology, Kanpur. The survey during 2021-22 and 2022-23 results indicated that maximum disease severity were recorded in Kanpur Dehat (24.67%), while the minimum in Kannauj (14.21%) district. Symptomatology study revealed that the infected seedlings were developed a dark spot on lower leaves which leads to damping off. Initially small yellow specks are produced on leaves which enlarge into circular, dark to tan coloured concentric rings giving a target board effect. The koch postulates of the pathogenicity successfully proved and isolated pure pathogenic culture of the fungus produced profuse cottony mycelium, whitish to grey in colour at first and turned dark with age. The conidia are brownish black, obclavate with 4-11 transverse and 0-4 longitudinal septa measuring 28.85-67.28 11.39-13.91 μm with the average of 41.90×12.94μm. The culturalstudy of pathogen on different media showed, maximum mycelial growth was recorded on Potato Dextrose Agar medium (89.07 mm), while minimum onStarch Agarmedium (22.16 mm) after seven days of inoculation. Environmental factor also influenced the disease severity of the pathogen at different stages of crop growth. The disease severity of the pathogen was with weather parameters prevailed during the respective stages. It was found that maximum(r=-0.517) and minimum(r=-0.667) temperature were negatively correlated with percent disease severity, while relative humidity (r=0.485) and rainfall (r=0.141) positively correlated. The rainfall (0.142) was weak positively correlated with disease severity. Under in-vitro, five bioagents and ten botanical were tested. Out of bioagents T. Viride (74.81 %) found most effective and least in T. Virens (41.77%), while in botanicals, garlic clove extract (71.09%)at 15 per cent concentration was highly effective, and least in onion extract (56.55%)in minimizing the growth of A. brassicicola,. Similar inhibitory effects on mycelial growth were observed at 10 and 5 per cent concentrations. Similarly, under in-vitro condition contact and systemic fungicides were tested at different concentrations. Out of contact fungicides, Dodine showed the maximum inhibition (78.95%) and least in Metalaxyl+Mancozeb (62.43%) at 150 ppm, while in systemic fungicides, Propiconazole (100 %) showed maximum inhibition while Azoxystrobin (82.06%) against A.brassicicola, at 150 ppm. Under field conditions during 2021-22 and 2022-23, the average minimum disease intensity was recorded with the treatment of Propiconazole 25wp + Garlic clove extract 10% (5.50%), while maximum disease intensity (19.52%) with Neem leaf extract 10 per cent. Similarly, the average maximum cauliflower yield (15.15 kg per plot) was obtained with Propiconazole 25wp + Garlic clove extract10%, while minimum (9.94 kg per plot) with Neem leaf extract 10 per cent On the basis of above findings it is recommend that, application of the Propiconazole 25 WP + Garlic cloveextract 10 per cent has been found effective in terms of reduction of the A. brassicicola intensity and increased yield of cauliflower.ThesisItem Open Access Taxonomy And Parasitism Of Alternaria Spp. Associated With Some Umbelliferous Spices And Vegetables(CSA University of Agriculture and Technology;Kanpur, 2007) Mukesh Kumar; Udit Narain
