Variability and management studies of Botrytis cinerea causing grey mould in gladiolus
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Date
2015
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Publisher
YSPU
Abstract
Botrytis Grey Mould (Botrytis cinerea Pers. ex Fr.) in gladiolus is one of the major limiting factors in its
cultivation affecting both yield and fruit quality in Himachal Pradesh. Present investigations were undertaken with an objective to study the prevalence of the disease, variability among the Botrytis isolates on the basis of cultural, morphological, pathological and molecular parameters. The role of environmental factors in disease development, germplasm screening and devising of suitable disease management strategies were elucidated. Botrytis grey mould was found to occur in moderate to severe form in different gladiolus growing areas of Solan, Shimla, Mandi, Bilaspur, Kullu and Sirmour districts of Himachal Pradesh. The average disease incidence and severity in two years of surveys (2012- 2013) ranged between 14.83 to 64.92 and 2.98 to 33.33 per cent, respectively. Based on the cultural, morphological and molecular characterization, out of fifteen isolates, fourteen were identified as Botrytis cinerea and one was identified as
Botrytis fabae. Mycelial growth and sporulation was recorded maximum on PDA media at temperature of 20oC however sporulation was obtained excellent at temperatures 10 and 15oC. Sclerotia formation was more at low temperature compared to high temperatures (30oC). Fructose and asparagines were adjudged best as carbon and nitrogen sources for multiplication of the pathogens. There was variation in among the isolates in respect to physiological studies. Molecular variability was carried by using 45 RAPD primers, out of which only 25 primers were amplified and showed 100 per cent polymorphism. DNA amplification was done by using 16 ISSR primers, only 14 primers were amplified and gave 143 polymorphic bands and showed 100 per cent polymorphism. Moderate temperature (22±2oC) coupled with high RH (80%) favoured the disease development under natural epiphytotic conditions. Esta Bonita, Grand Prix and Amesterdam cultivars
were found to be resistant against grey mould under natural conditions. In vitro effect of different fungicides on mycelial growth of B.cinerea revealed that two fungicides i.e., Quintal and Contaf gave no mycelial growth with cent per cent inhibition at all the concentrations tested. Amongst different bioresources, minimum growth was recorded in Allium sativum and Azadirachta indica. Amongst 15 plant oil peppermint, geranium, palmarosa, citronella and oregano completely inhibited the growth of B. cinerea. Integrated disease management studies revealed that the treatments, Quintal+ Allium sativum + Neem oil and Contaf + Allium sativum + Neem oil gave minimum disease severity and maximum disease reduction of 94.40 and 93.19 per cent, respectively. Plant growth parameters viz., plant height, spike length,no. of flowers/ plot and yield also increased with application of these combinations in field conditions during the years 2012-2013.
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Keywords
fungi, diseases, planting, biological phenomena, botrytis cinerea, biological development, developmental stages, oils, gladiolus, pathogens