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2013 - 20172
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Subject: Plant Pathology × Author: Gairola, Kalpana × Start date: 2000 × Type: Thesis ×
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    ThesisItemOpen Access
    Early detection and management of white rust disease (Albugo candida) in rapeseed mustard
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2017-08) Gairola, Kalpana; Tewari, A.K.
    Among various diseases reported to occur on rapeseed mustard, white rust caused by Albugo candida is considered as one of the most important disease due to its destructive nature, wide distribution and grain yield losses of 17-34 per cent. The present investigation was carried out with the objectives of: early detection of A. candida, the cause of white rust disease; evaluation of rapeseed-mustard genotypes in field and in glasshouse (at cotyledonary and true leaf stage) and evaluation of some new fungicides for the effective management of the disease. The early detection of A. candida was done by PCR-based assay and light microscopy. In PCR based assay the primers ITS1 (3’-GAGGGACTTTTGGGTAATCA-5’) and Short ITS JV34 (3’- CGCCATTTAGAGGAAGGTGA-5’) and JV37 (3’-GTCAAGCAAAACAT-5’) were used to amplify the ITS region of A. candida and Alternaria brassicae. PCR amplification of A. candida from inoculated symptomatic and asymptomatic leaves yielded PCR products of 1200 bp and 600 bp of ITS1 and Short ITS primers, respectively whereas no bands were amplified in A.brassicae. This confirmed the presence of A. candida in asymptomatic inoculated leaves at early stage i.e. 1, 2, 3, 4, 5 and 6 DAI. In light microscopy the presence of pathogen structures were observed from inoculated symptomatic and asymptomatic inoculated leaves. This presence of pathogen structure viz. mycelium and sporangia was observed in asymptomatic leaves at early stage at 6,7,8 and 9 days after inoculation and from symptomatic leaves at 10 and 11 days after inoculation where as no fungal structure in healthy mustard leaves after staining with 1 percent cotton blue in lacto phenol and 0.4% trypan blue. A large number of rapeseed-mustard materials collected from different sources evaluated in field and in glasshouse (at cotyledonary and true leaf stage) revealed that for the confirmation of resistant sources against white rust disease it is very essential to evaluate Brassica materials first in field and then in glasshouse at both the stages i.e. at cotyledonary and true leaf stage under high disease pressure because some Brassica materials escaped from the disease in field but found susceptible in glasshouse at both the stages (EC-399299) or only at true leaf stage ( Katili local, E. sativus, Basanti and Banarasi rai, PWR-14-8, PWR-14-9, PWR-14-10, PWR-14-11, RMT-1-10-1, IC 597942 and IC265495). Among various fungicides Metalaxyl 8% + Mancozeb 64% (Ridomil MZ @ 0.25%) and a biological origin Azoxystrobin (Amistar 25 EC @ 0.1%) were found highly effective in inhibiting sporangial germination in-vitro and were found highly effective in controlling white rust disease (no occurrence of disease) in glasshouse and field in increasing grain yield and test weight followed by Propiconazole, Tebuconazole+Trifloxystrobin, Trifloxystrobin, Kresosim methyl (each at 0.1%). Garlic bulb extracts (2%) was also found effective in managing the disease even better than some old recommended fungicides
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    ThesisItemOpen Access
    Drechslera blight of soybean: Symptomatology, etiology and management
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2013-06) Gairola, Kalpana; Dubey, K.S.
    Drechslera blight of soybean caused by Drechslera glycini is widely distributed in warm and humid areas, especially in the tropics and it causes heavy losses (quantitatively and qualitatively). Under artificial inoculated conditions brownish spots were observed on leaves near the leaf margin with light brown centre and dark brown margin. and brownish discoloration were observed on hypocotyls and cotyledons. Seven media were tested for the growth of the Fungus, wherein, Oat meal agar was best for growth as well as sporulation of the test fungus. The pathogen grew best at pH 7 and 350C temperature. In-vitro antagonistic potential of six fungal and three bacterial bioagents wherein T. harzianum showed as potential strong potent bioagent against D. glycini. Among eight organic matters amended soil extracts tested, Press mud was found most effective against test fungus. Out of eight organic matter amended soils, inoculated with the test pathogen, Press mud was found most effective and gave highest seed germination. Tea waste was found best for nodulation and Press mud showed least disease severity as well as minimum preemergence mortality. while the post emergence mortality was found least in Bannana peel amended soil. Among eight Botanical extracts tested for their antifungal property, Ginger was found most effective. Out of Nine fungicides tested in which Tabuconazole gave maximum control of the test pathogen and Tridemefon, Thiophanatemethyle and Companian were found less effective.