Alternaria blight caused by Alternaria brassica and A.
brassicicola singly or by mixed infection is one of the most widespread and
destructive diseases of oilseed brassicas globally. Different chemicals,
including systemic fungicides, have been used for the management of this
disease. However, with the increase in environmental pollution and present-day
public perception on pesticide contaminants of foods, especially the edible
oils, the development of alternative economical and eco-friendly approaches for
disease management is needed. Several plant products are known to have
antifungal activities, which are environmentally safe and non-phytotoxic. In order to identify the effective and
economic molecules of fungicides against Alternaria blight, a field trial was
conducted during Rabi 2021-22 and 2022-23 at Nagaon, Assam, in rapeseed
(Brassica rapa L. var. toria). The trial was conducted with seven fungicides
and replicated thrice (RBD) to assess the most effective fungicide in managing
the disease. Among the different fungicides tested, the ready-mix formulation
of tebuconazole 50% + trifloxystrobin 25% WG resulted in maximum reduction in
disease severity both on leaves (54.1 %) and pods (55.7 %). Thus, this
combo-formulation led to realization of the highest seed yield (1187 kg ha-1)
with a yield advantage of 78.5 % over the check. The highest net monetary
return (NR) of Rs. 39001 ha-1 with a benefit-cost ratio (B:C) of 2.02 was
received in the treatment, followed by azoxystrobin 23 % SC @ 1 ml l-1 with
46.1 % and 45.8 % reduction in disease incidence, respectively on leaves and
pods and yield increase of 54.8 %. Interestingly, when B:C ratio was
calculated, azoxystrobin 23% SC recorded the highest B:C (2.31) with an NR of
Rs. 37959 ha-1. The combination of trifloxystrobin and tebuconazole acts as a
synergist, as the individual components have different modes of action.
Tebuconazole, a triazole, acts as a demethylation inhibitor (DMI) that hinders
the fungal cell wall synthesis and thereby acts as an obstacle for the fungal
growth and reproduction.
Author(s) Details
R. Chakrabarty
AAU-Zonal Research Station, Assam Agricultural University, Shillongani,
Nagaon-782 002, India.
H. Kalita
AAU-Zonal Research Station, Assam Agricultural University, Shillongani,
Nagaon-782 002, India.
P. Buragohain
AAU-Zonal Research Station, Assam Agricultural University, Shillongani,
Nagaon-782 002, India.
R.N. Borkakati
AAU-Zonal Research Station, Assam Agricultural University, Shillongani,
Nagaon-782 002, India.
B. Kalita
AAU-Zonal Research Station, Assam Agricultural University, Shillongani,
Nagaon-782 002, India.
Please see the book here :- https://doi.org/10.9734/bpi/fsarh/v5/6811
