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Authors: Santoshreddy Machenahalli
Advisor: M.S.L. Rao
Title: Studies on Downy Mildew of Gherkins Caused by Pseudoperonospora cubensis (Berk. And Curt.) Rostow.
Publisher: UAS, Dharwad
Type: Thesis
Agrotags: Plant pathology
Abstract: Gherkin or pickling cucumber (Cucumis sativus L.) is an exotic vegetable being grown in several parts of Karnataka for export. This vegetable is suffering from several economically important foliar diseases like downy mildew, which is posing a serious threat to the successful large scale cultivation of this vegetable in Karnataka. Survey results indicated that severity of gherkin downy mildew was more in Koppal followed by Gadag, Haveri, Dharwad, Bellary, Bagalkot districts and the per cent disease index varied from 63.21 to 70.58. The disease starts from 20 days after sowing, almost all stages of the crop were found to be susceptible. Among the fourteen genotypes evaluated against P. cubensis, genotype ‘Sparta’ was found moderately resistant. Three genotypes viz., Vertina, Nun-5508 and Shakthi–RZ were found to be moderately susceptible. The size of sporangia of P. cubensis from different hosts varied between 45-56 × 26- 37μm. The maximum sporangial germination observed at 20°C with 100 per cent relative humidity. Among the different fungicides, botanicals and bioagents tested against P. cubensis, Fenamidon + Mancozeb, Metalaxyl + Mancozeb, garlic bulb extract and Pseudomonas fluorescens were found superior, in inhibiting the sporangial germination under in vitro condition. Integrated disease management study under field conditions revealed that, the treatments with foliar sprays of Metalaxyl- MZ®Fenamidon + mancozeb ® Dimethomorph at 0.2 per cent recorded least per cent disease index which was found on par with Metalaxyl-MZ and Fenamidon + Mancozeb spray alone. As the rotation of different molecules of fungicides avoids the resistance development by the pathogen against fungicides, rotation of fungicides is beneficial rather than the single molecule usage.
Subject: Plant pathology
Theme: Studies on Downy Mildew of Gherkins Caused by Pseudoperonospora cubensis (Berk. And Curt.) Rostow.
Research Problem: Studies on Downy Mildew of Gherkins Caused by Pseudoperonospora cubensis (Berk. And Curt.) Rostow.
Issue Date: 2011
Appears in Collections:Thesis

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