CHANDEL, SUNITAREETIKA2017-03-162017-03-162017http://krishikosh.egranth.ac.in/handle/1/5810005030ABSTRACT Black spot disease is a serious threat to rose production in India. Black spot of rose caused by Marssonina rosae (Lib.) Lind. with its perfect stage Diplocarpon rosae (Wolf) causes heavy losses to roses worldwide. Therefore detailed investigations were undertaken with the objectives to record the disease severity of black spot of rose in Solan and Sirmour districts of Himachal Pradesh, and to study the physiological, epidemiological parameters of the pathogen and device suitable management strategies such as germplasm evaluation and chemical methods. Survey revealed that disease was prevalent in both districts surveyed with severity range varying between 24.48 to 78.65 per cent, maximum at Nauni (76.33 %) of Solan and minimum at Sargaon (24.48 %) of Sirmour. The pathogen was identified based on the morphological features as Marssonina rosae (Lib.) Lind. Most distinguishing morphological features of pathogen were production of cylindrical, two celled and hyaline conidia measuring in length (22.1 – 25.3 μm ) and width (5.3 – 7.1 μm). The pathogenicity was obtained within 15days of inoculation. In cultural studies, out of five solid media maximum radial growth was recorded on Malt Extract Agar (76.56mm) with sporulation count of 55.02 x 104 and out of five liquid media maximum dry mycelial weight (292.20mg) and sporulation of 24.46 x 104 spores/ml was observed on Richard’s medium. Among various temperature regimes, the maximum radial growth (88.00 mm) was observed at temperature 25º C with sporulation count of 54.23 x 104. Two pH levels of 6.5 and 7.0 were found best to attain maximum vegetative growth and sporulation of Marssonina rosae. Effect of different meteorological parameters on progress of black spot of rose (cv. ‘White Delight’) was studied under field conditions and it was observed that the disease severity become apparent in first week of June with minimum disease severity of 3.55% which gradually increase in respective months and assumed highest proportion (72.76%) in the mid of October, 2015. The mean temperature ranging from 11.4 to 26.4ºC, relative humidity I,II 44-67%, cumulative rainfall 46.2mm and total sunshine hours 58.8 favored the disease spread. Screening of 135 rose varieties indicated that none of the varieties were categorized under immune class but only one variety is highly resistant against black spot of rose i.e. ‘Anabel’ while twelve and three showed resistant and moderately resistant reactions. In vitro evaluation of fourteen systemic and non- systemic fungicides revealed that three systemic fungicides Nativo, Insignia and Cabrio top were most efficacious. Highest inhibition (84.3%) of mycelial growth was recorded in Nativo followed by Insignia and Cabrio top while Indofil M gave maximum inhibition (76.13%) out of the non- systemic fungicides. Same fungicides under in vivo conditions reported effectiveness by reducing the disease severity of black spot and increasing the average flower yield per plant.ennullThesis