Abstract:
Weather factors are key determinants in ecological disease
management in sustainable agriculture, while judicious crop
management systems deliver better control over rice
diseases in tropical conditions. This study was designed to
explore the effect of weather factors under different crop
management systems and seasons on Rice Brown Leaf Spot
(RBLS) disease incidences caused by Bipolaris oryzae in the
tropical dry zone of Sri Lanka. The incidence of RBLS was
measured under Conventional, Reduced, and Organic crop
management systems commencing from the first occurrence
of disease symptoms, at three-day sampling intervals in the
tropical dry zone during wet (Maha) 2018/19 and 2019/20,
and dry (Yala) 2019 and 2020 seasons. Secondary data on
weather parameters were collected from the regional
weather station. The RBLS incidences were highest in the
wet season and were most abundant at the reproductive
stage. The disease incidence dynamics over time were found
to be similar among all the crop management systems in
three seasons. The cumulative amount of rainfall seven days
before the disease observation (RF7), the day-RH (DRH), and
the maximum (TMAX48) and average temperature
(TAVG48) that were recorded 48 h before the disease
observations were found to be significantly correlated with
the disease incidence of crop management systems in the
wet season. DRH and minimum temperature (TMIN72) of 72
h before the disease observed in the wet season resulted in
higher disease incidences. The RBLS disease can be managed
concerning the crop management systems under high DRH
and TMIN (20-25 ℃) in the wet season.
