In the northeastern Himalayan area of India, effective fungicide spray schedules are used to control late blight (Phytophthora infestans) of potatoes (Solanum tuberosum).

Abstract

One of the most damaging phytopathogens that causes late blight disease in potatoes (Solanum tuberosum L.) is
Phytophthora infestans (Mont.) de Bary, a member of the order Peronosporales. At any stage of crop
development, the disease may create severe disease outbreaks that result in total defoliation and significant yield
loss. The disease signs can emerge on leaves, petioles, stems, and tubers. At Chesrimai GP, Charilam block,
Sepahijala, Tripura, field tests were carried out in 2020–21 and 2021–22 to determine the best fungicide
management techniques to lessen the losses brought on by the destructive disease. In order to determine the
optimal spray schedule against late bight disease, the experiment was set up in three replications using a
randomised block design (RBD) with eight treatments containing various fungicides in various combinations.
The best-performing treatments were found to be Mancozeb 75% @0.25% at 35 days after sowing (DAS),
Cymoxanil 8% + Mancozeb 64% @0.25% at 42 DAS, Mancozeb 75% @0.25% at 49 DAS, and Cymoxanil 8%
+ Mancozeb 64% @0.25% at 15.00 and 12.75%), the lowest mean disease severity (1.58% and 0.93%), and the
highest tuber yield (21.27 and 21). Additionally, throughout 2020–2021 and 2021–2022, yield increased above
control by 26.6 and 27.7%, respectively, and the pooled incremental cost benefit ratio (ICBR) of 1:16.09 was
shown to be the greatest of all treatments. Under field circumstances, the late blight disease of potatoes may be
successfully managed using an effective spray schedule that includes contact fungicide for prophylaxis and
prevention, followed by translaminar/systemic + contact fungicide.