Spatial analysis of potato black scurf disease distribution using GIS and variability of Rhizoctonia solani isolates in Central Karakoram National Park Gilgit-Baltistan, Pakistan

Black Scurf

Azhar Hussain, Muhammad Saeed Awan, Francesco Morari, Sh. M. Iqbal3, Syed Najam ul Hassan

Key words: Black scurf, potato, Distribution, Rhizoctonia solani, IDW, Geostatistics GIS, CKNP and Gilgit-Baltistan, Pakistan.

Abstract:

Spatial analysis of black scurf distribution and morphological variability were carried out during the year 2012-13 using geographical information system and geostatistics techniques in four valleys & twenty four villages of CKNP region. During the studied it is showed that among the twenty four village eight villages found > 60 % disease prevalence, thirteen in range of 40 – 60 % and three villages < 40 % while disease incidence and severity were recorded as eight villages > 15 %, thirteen villages 10-15 % and three villages <10 % as well as disease severity; four villages >5, thirteen 3- 5 and seven villages in < 5 %. The ranged of disease prevalence (25.0 – 75.0 %), incidence (5.55 – 23.89 %) and severity (1.67 -6.55 %) were recorded. Twenty isolates of R.solani were obtained from the infected tubers of potato and characterized their colony growth rate mmd-1, different pH and temperature level. On the basis of colony growth rate (CGR), the isolates were categorized as slow, medium and fast. Twelve isolates (60 % of the total) showed medium growth (10-20 mm-day-1) while eight isolate (40 % of the total) showed fast growth (> 20 mm-day-1). Effects of different temperature and pH levels on CGR of the isolates were assessed. All isolates attained (above 80 mm CGR) at 30 ºC, (70-80 mm CGR) at 25°C and Optimum pH for CGR of isolate were 6.5-7.5 while cluster analysis of twenty isolates were categorized into two main groups i.e. A and B. 70 % of the isolates were classified in cluster A while 30 % in B.

Article Source: Volume 4, Number 2, January 2014 – IJB

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