Loading...
Thesis
Browse
1 results
Search Results
ThesisItem Embargo Etiology And Management Of Fruit Drop In Kinnow Mandarin(Punjab Agricultural University, 2023) Damanpreet Kaur; Amrinder KaurFruit drop in Kinnow mandarin is a major problem causing quantitative and qualitative losses, globally to the growers. Among the 33 diseased samples collected during the survey from different Kinnow growing orchards of Punjab, Colletotrichum spp. was found to be associated with all the isolates. Morphological characterization of 33 isolates (C-1 to C-33) revealed that the fungus produced creamy white to light grey colony with orange conidial mass in centre. The conidia were non-septate, cylindrical with round apex having oil droplets, ranging in size from 10.26 x 2.77 to 15.70 x 4.82 µm. An irregular shaped brown to black acervuli was produced in isolate C-1, C-4, C-5, C-10, C-19, C-24, C-25, C-29 and C-30 ranging from 130.00-164.30 µm in length and 145.50-168.40 µm in breadth having erect and septate, brown to black setae. Molecular characterization of all the 33 isolates done by amplification of ITS region, ACT and TUB2 genes revealed that all the isolates were of Colletotrichum, whereas amplification of species-specific primer CgInt/ITS4 confirmed that all the isolates belong to Colletotrichum gloeosporioides complex and no amplicon was observed in any of the isolates with primer pair CaInt2/ITS4 (C. acutatum). The phylogenetic analysis of two isolates C-4 and C-19, selected on the basis of high virulence and growth rate proved that Colletotrichum siamense (belonging to gloeosporioides complex) is associated with fruit drop in Kinnow mandarin under Punjab conditions. For management of the disease, different fungicides, botanicals, bio-control agents and nanoformulations were evaluated both under in vitro and field conditions, among the systemic fungicides, azoxystrobin 18.2% + difenoconazole 11.4% SC and propiconazole 25% EC proved to be the most effective by inhibiting 100 % and 88.33% mycelial growth at 25 ppm concentration, respectively. Among, non-systemic fungicides copper oxychloride 50% WP exhibited 100% mycelial growth inhibition at 1000 ppm concentration. In case of botanicals and bio-control agents, maximum mycelial growth inhibition was shown by neem extract (47.96%) and T. harzianum (55.12%), respectively. Nano-particles were not much effective and showed only (22.03-22.77%) growth inhibition of the pathogen. Under field conditions, the fungicides treatment of azoxystrobin 18.2% + difenoconazole 11.4% SC (61.19% and 63.81%) and propiconazole 25% EC (56.95% and 59.12%) were significantly effective in reducing fruit drop over control while neem extract (32.91% and 33.61%) was at par with T. harzianum with (30.92% and 33.41%) reduction in fruit drop over control during 2021 and 2022, respectively. Thus, the disease management strategies could be further incorporated in the IDM programmes for effective management of fruit drop in Kinnow mandarin.
