TITLE:
Effect of Some Environmental Factors on Incidence and Severity of Angular Leaf Spot of Cotton in Yola and Mubi, Adamawa State, Nigeria
AUTHORS:
N. Z. Tuti, H. Nahunnaro, K. Ayuba
KEYWORDS:
Angular Leaf Spot, Cotton, Rainfall, Relative Humidity, Disease Incidence and Disease Severity
JOURNAL NAME:
World Journal of Engineering and Technology,
Vol.3 No.3B,
August
25,
2015
ABSTRACT: Environmental factors such as relative
humidity and rainfall generally have been found to increase the incidence, rate
of spread and severity of diseases thereby reducing yield of crops. Study was
conducted on five cotton varieties, which were artificially inoculated with
bacterial blight pathogen to determine the effects of rainfall and relative
humidity on incidence and severity of angular leaf spot (ALS) and yield of seed
cotton in Yola and Mubi. Results showed that the severity of ALS was higher in
Yola (58.65%) at 13 WAS assumed to be due to higher relative humidity range of
76% - 87% and low rainfall of 2 - 40.6 mm. This is assumed to have favoured
disease development as against that of Mubi location which recorded lower
severity (51.11%) due to lower relative humidity (42% - 55%) and rainfall (37 -
73 mm). Results further revealed that at 13 WAS, SAMCOT-8 had low incidence
(66%) and severity (39%) in Yola. This was against the much higher
corresponding incidence and severity of 82% and 42% respectively that was
observed in Mubi during the same period. SAMCOT-10 and SAMCOT-9 varieties were
found to be highly susceptible to the disease at the same period. SAMCOT-8
recorded the highest yield of 390.00 kg?ha?1 in Yola and 868.09 kg?ha?1 in Mubi
while the lowest yields of 227.17 kg?ha?1 was observed on SAMCOT-10 in Yola
while 461.61 kg?ha?1 was obtained on SAMCOT-9 in Mubi. The variation in yield
among these varieties might be due to the differences in their reactions to the
disease. There is a need to conduct further trials in these locations to
confirm the level of resistance or other aspects of these varieties to the
disease.