Variability in Alternaria mali (Roberts) and Management of Alternaria Leaf Blotch of Apple through Systemic Acquired Resistance Activators

DSpace/Manakin Repository

Variability in Alternaria mali (Roberts) and Management of Alternaria Leaf Blotch of Apple through Systemic Acquired Resistance Activators

Show full item record

Title: Variability in Alternaria mali (Roberts) and Management of Alternaria Leaf Blotch of Apple through Systemic Acquired Resistance Activators
Author: Sofi, Tariq Ahmad (Scholar); Beig, Muzafer A. (Guide)
Abstract: Seven districts of the valley were surveyed to record the status of Alternaria leaf blotch disease of apple. The disease was prevalent in all the districts surveyed with an overall disease incidence and intensity of 42.11 and 21.68 per cent, respectively. Highest disease incidence and intensity was recorded in district Pulwama and least in district Shopian. Pathogenic behaviour of twenty one isolates of Alternaria mali, isolated from apple leaves of cv. Red Delicious, was established following Koch,s postulates. Morpho-cultural and molecular studies were made to ascertain the prevalence of variability among the isolates. Colonies varied in their cultural behaviour ranging from velvetty to cottony, mostly appressed, with regular to irregular margins. Colour of the colonies ranged between light to dark olivacious. Growth rate of isolates was between 5.86 to 8.21 mm with fast growth in Am-13 and least in Am-5. Isolates impregnated media with colour ranging between grey to brown. Morphological studies of isolates revealed variations in their colour, size, shape and septations of hyphae, conidiophore and conidia. Significant variations were observed in conidiophore and conidial septations. Average conidial size varied from 21.36-31.74 µm x 8.34-14.48 µm. Isolates when tested for their virulence revealed variation in incubation period and number and size of the lesions produced. Isolate Am-1 was categorized as most virulent. The dendrogram analysis based on cultural, morphological and pathogenic studies revealed high diversity within Alternaria mali population. At 67 per cent similarity matrix all the isolates formed 2 clusters with 12 isolates in cluster I and 9 in cluster II. However dendrogram on molecular (RAPD) basis revealed 5 clusters at 68 per cent Dice similarity coefficient. There was no congruence between the RAPD pattern and cultural, morphological and pathogenic characters. Isolates that were identical for one spectrum were often dissimilar for other spectrum. Commercially important apple cultivars were screened for resistance against Alternaria mali and disease resistance of variable magnitude was observed in available germplasm. White Dotted Red was highly resistant and American Apirouge resistant in reaction. Red Delicious and Red Gold were highly susceptible. All the Systemic Acquired Resistance (SAR) chemicals tested against the disease significantly lowered the disease as compared to check. β-aminobutyric acid (BABA) at a concentration of 2000 ppm was most effective with least disease intensity before and after pathogenic inoculation. The other SAR chemicals in decreasing order of their efficacy were tri-potassium phosphate (K3PO4), benzothiadiazole S-methyl ester (BTH), 2,6-dichloroisonicotinic acid (INA), calcium hydroxide (Ca(OH)2), di-potassium ortho-phosphate (K2HPO4) and calcium carbonate (CaCO3). Penconazole used as standard check proved superior to all the SAR activators, except BABA.
URI: http://dspaces.uok.edu.in/jspui//handle/1/1079
Date: 2011


Files in this item

Files Size Format View
003.docx 13.08Kb WordPerfect View/Open

This item appears in the following Collection(s)

Show full item record

Search DSpace


Advanced Search

Browse

My Account