Progress of citrus scab (Elsione fawcetti) on rough lemon in relation to prevailing meteorological parameters

The study on citrus scab (Elsinoe fawcetti Bitancourt and Jenkins) on rough lemon nursery from 1998 to 2007 in relation to prevailing weather parameters indicated that the disease appeared in May and attained its peak in September, and thereafter it declined. The peak severity of the disease was recorded in rainy season particularly in the month of August and September. The highest disease severity was recorded in the month of September (47.66%) and the lowest in December (1.65%). The super imposition of meteorological parameters and disease development data revealed that minimum temperature of 18.46 to 27.38°C, maximum temperature of 31.06 to 35.72°C, RH (morning) of 72.13 to 76.43 per cent, RH (evening) of 38.28 to 53.97 per cent, RF 26.06 to 52.57 mm, Cd of 3 to 9 and Rd of 2 to 5 favoured disease development. However, maximum incidence (47.66%) was recorded at temperature between 25.24 to 34.70°C; RH between 52.55 to 76.43 per cent, 34.04 mm rainfall, 5 cloudy days and 3 rainy days. The correlation of the disease severity with minimum (+0.569) and maximum (+0.311) temperature, morning (+0.026) and evening (+0.804) RH, RF (+0.377), number of cloudy (+0.716) and rainy days (+0.250). The correlation was significant with evening relative humidity and number of cloudy days.