RELATIONSHIP OF METEOROLOGICAL VARIABLES WITH LENTIL GREY MOLD AND ITS MANAGEMENT

Abstract

Botrytis grey mold (BGM) is the most important biological constraint for lentil crop in Pakistan. During 2007-08 and 2008-09, 912 varieties/lines were evaluated under field conditions. There was no line found to exhibit immunity against Botrytis grey mold. 452 and 236 varieties/lines exhibited moderately resistant response against Botrytis grey mold during 2007-08 and 2008-09, respectively. During 2007-08 and 2008-09, 652 and 863 varieties/lines exhibited susceptible response to Botrytis grey mold. 166 varieties/lines exhibited highly susceptible response to Botrytis grey mold during 2007-08, while 171 one exhibited highly susceptible response to Botrytis grey mold during 2008-09. Maximum disease development occurred at temperature 23-26 oC and 18-24 oC, relative humidity at 5 pm 36-54 %, rainfall 0-3 mm, wind speed 3-5 Km/h and sun shine 6-10 hours. The data of susceptible to highly susceptible lines/ varieties and meteorological variables were subjected step wise regression analysis based on two years data a model consisting of all environmental variables explained 98 % variability in disease development. When these were split by years; a three environmental variable model consisting of sun shine hours, relative humidity % at 8 am, relative humidity % at 5 pm explained 96 % variability in botrytis grey mold severity during 2008. However, during 2009, four environmental variables model consisting of wind speed Km/h at 8 am, max temperature oC, relative humidity % at 5 pm and rain fall mm explained 99 % variability in botrytis grey mold severity. For the management of BGM, three antagonists (Trichoderma harzianum, Aspergillus flavus and A. niger), three plant extract (Azadirachta indica, Bougainvillea spectabilis and Eucalyptus terticornis) coupled with three fungicides including Topsin-M, Cabriotop, and Antracol with different doses were used in laboratory experiment to assess their effectiveness against the colony growth of Botrytis cinerea. Out of these, Cabriotop, Trichoderma harzianum, Azadirachta indica were found effective in inhibiting the mycelium growth of the fungus. These same treatments were also found effective in greenhouse experiments. The most effective treatments were tested on two varieties and one advanced line under field condition. Among these Cabrio top at 150 ppm was most effective in controlling BGM on Masoor-85, Masoor-93 and line 00518. The protective spray of these treatments was significantly effective compared to curative spray.