M. M. Rahman
TCRSC, BARI, Bogra
M. A. Ali
Department of Plant Pathology, BAU, Mymensingh
M. U. Ahmad
Department of Plant Pathology, BAU, Mymensingh
T. K. Dey
Director, PRC, BARI, Ishurdi, Pabna Banladesh
Rhizoctonia solani, Stem canker, Black scurf, Potato, Seed tuber
Tuber Crops Research Sub-Centre (TCRSC) of Bangladesh Agricultural Research Institute (BARI), at Chalopara, Bogra
Pest Management
Healthy as well as R. solani infected seed tubers of a susceptible variety, Diamant were collected from the Breeder Seed Production Centre (BSPC) Debiganj under Panchagarh district. Both healthy and infected potato seed tubers were mixed before planting at 0, 5, 10, 20, 50 and 100% infected seed tubers. The experiment was conducted at the Tuber Crops Research Sub-Centre (TCRSC) of Bangladesh Agricultural Research Institute (BARI), at Chalopara, Bogra district during 2007-2008 potato growing season. The experiment was laid out in a randomized complete block design with four replications. The unit plot size was 3 m × 3 m. Block to block and plot to plot distances were 100 cm and 50 cm, respectively. Row to row and tuber to tuber distances were 60 cm and 25 cm, respectively. Recommended doses of fertilizers and manure were applied as suggested by Tuber Crops Research Centre, BARI, Gazipur. Cowdung was incorporated in the soil during land preparation at the rate of 10 t/ha. Urea, Triple super phosphate (TSP), Muriate of potash (MOP), Gypsum, Zinc sulphate and Boric acid were applied at the rate of 360, 220, 250, 120, 14 and 6 kg per hectare, respectively. Half of urea and the entire amounts of TSP, MP, Gypsum, Zinc sulphate and Boron were applied at the time of final land preparation. Tubers were planted on 30 November, 2007. Rest half of urea was applied at 30 days after planting. Weeding was done at 25 and 50 days after planting. Earthing up was done at 30 days after planting. Irrigation was applied at 25 and 45 days after planting. Dursban 50WP (Chloropyrifos) @ 0.5% and Admire (Imidacloprid) @ 0.1% were applied to control cutworm and aphid, respectively. Secure (Pyriminamine) @ 0.1% was sprayed at 10 days intervals as preventive measure against late blight of potato. The crop was harvested on 27th February, 2008. Data on germination, number of stems per hill, plant height, disease incidence, percent disease index (PDI), tuber infection and yield were recorded. Data on disease incidence were recorded at 70 days after planting. To collect data on disease incidence, 20 plants were uprooted carefully from each plot, washed with tap water and checked for infection. Number of infected and healthy plants was counted in each plot and incidence percentage was calculated based on total number of plants checked. Disease severity was indexed on a 0-6 scale (Dey 2010), where 0=No symptom on stolon, 1=Minute brown lesion on stolon or root, 2=Moderately brown lesion on stolon and curling tendency on central leaf, 3=Stolon symptom discolored accompanied by brown discoloration on roots, 4=Brown to black discoloration on underground parts, tissue discoloration and tissue squeezed/curling of growing leaves, 5=Profuse emergence of auxiliary leaves and leaf size reduced markedly with pale green margin, and 6=Production of aerial tubers with green colour. The plants were checked individually and categorized into different group according to the indexing scale. The number of stem canker infected plants under each grade was recorded and percent disease index (PDI) was calculated using the following formula: PDI = (Class frequency/Number of plants assessed X highest score) x 100. Incidence of black scurf was recorded at harvest. The black scurf infected tubers were separated into three groups such as russet, deformed and sclerotia. The number of tubers under each group was counted and the respective weight was recorded. Number and weight of healthy tubers of each plot was also recorded. Data on different parameters were analyzed using computer program MSTAT-C. Differences among the treatment means were compared following Duncan’s Multiple Range Test (DMRT).
Bangladesh J. Plant Pathol.29 (1&2):29-32, 2013; ISSN 2012-9279
Journal