Int.J.Curr.Microbiol.App.Sci (2018) 7(9): 3495-3502 3495 Original Research Article https://doi.org/10.20546/ijcmas.2018.709.433 Relationship between Weather Parameters and Sunflower Powdery Mildew (Erysiphe cichoracearum DC) in Various Sunflower Sowing Dates A. Bheemaraya*, M.M. Jamadar and Shalini Huilgol Department of Plant Pathology, College of Agriculture, Bijapur, University of Agricultural Sciences, Dharwad – 580 005, Karnataka, India *Corresponding author ABSTRACT Introduction Sunflower (Helianthus annuus L.) is native of southern USA and Mexico. It is an important oilseed crop belonging to Asteraceae family and ranks third next to groundnut and soybean. It is a rich source of edible oil (40- 52%) having anticholesterol properties due to the presence of poly unsaturated fatty acids (55-65% linoleic acid and 20-30% oleic acid) which are known to reduce the risk of coronary diseases (Joksimovic et al., 2006). International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 09 (2018) Journal homepage: http://www.ijcmas.com A study was conducted in Karnataka, India from 2013-14 at College of Agriculture, Bijapur, (UAS, Dharwad) to know the effect of weather parameters in seven dates of sowing from I Fortnight (FN) July to I FN of October on sunflower powdery mildew. Weather correlations in I FN July dates shown significant positive impact of cloud cover at 20-1 days before observation (DBO) on the powdery mildew incidence, highly significant parameters that affected the powdery mildew at 20-16 DBO were minimum temperature (- 0.95) as well as maximum temperature (0.98) and maximum vapour pressure at (-0.95) at 5-1 DBO. The weather correlations in II FN July date of sowing indicated highly significant negative relation of minimum temperature (-0.88) at 20-1 DBO, At 5-1 DBO evening relative humidity (0.81) showed positive relationship. Correlations of weather parameters in I FN August sowing date indicated that at 20-1 DBO all the weather showed negative and highly significant relationship except cloud cover (0.83) which was positive and significantly correlated. Interestingly rainfall (-0.84) indicated negatively significant relationship with powdery mildew severity. The weather correlations in II FN August sowing indicated that at 20-1 DBO highly significant negative relationship with most of weather parameters but rain fall (-0.79) significant and negative at 20-1 DBO. Crop sown in I FN of September revealed At 20-16 DBO none of the weather parameters had the significant influence on the powdery mildew intensity except maximum temperature (- 0.83) which was significantly negatively correlated, here rainfall (-0.85) was significant and negatively affected the powdery mildew severity. In II FN September sowing indicated that highly significant and negative relation of maximum temperature (-0.95) among all the weather variables on powdery mildew intensity at 5-1 DBO. Powdery mildew severity in I FN October sown crop were observed except morning relative humidity (-0.78) at 20-1 DBO and maximum temperature (0.88) at 20-16 DBO. Keywords Dates of sowing, Powdery mildew (Erysiphe cichoracearum), Weather parameters Accepted: 24 August 2018 Available Online: 10 September 2018 Article Info