Antimycotic Potential Assessment of Trichoderma Species and Fungicides for Sustainable Management of Sclerotinia trifoliorum causing Stem and Crown Rot of Trifolium alexandrinum L.

Abstract

Sclerotinia trifoliorum, the fungal plant pathogen first reported in 2021 from Pakistan on Trifolium alexandrinum L. (Egyptian clover; an annual winter fodder crop), causing Stem and crown rot disease. About 46% to 55% incidence of this disease was recorded on E. clover cultivated in the irrigated tract of the country in 2018-19. This disease is subjecting significant crop losses and drastically reducing growth. An integrated disease management approach employing biological and chemical control was adopted to manage this wide-spreading fungal pathogen. The fungal antagonists, including Trichoderma harzianum, T. longibrachiatum, and T. asperellum Moreover, fungicides, including Thiophanate Methyl, Tebuconazole, Tubeconazole+Emdachloprid, Chlorothalonil+cymoxanil, Azoxystrobin, Pyraclostrobin+Metiram, and Mancozeb+Metalaxyl were tested under in vitro and field conditions. Among Trichoderma species, the best response was achieved by T. harzianum with 80.61% inhibition compared to control. Among concentrations of T. harzianum, the best response was achieved on 1/10 (1.24 cm) with 2.4 average No. of Sclerotia and 66% inhibition. Under filed condition experiments, the data regarding Disease severity in T. harzianum treated trays was 51.7% compared to untreated/control 73.5%. Besides disease control, the application of T. harzianum showed a significant increase in green and dry fodder weight (851 grams with 87 grams of dry weight) than untreated/control (561 grams with 55 grams of dry weight) in the fourth cut. For chemical evaluation, seven fungicides tested at three concentrations under in vitro trials among these Thiophanate methyl (0.5 cm) with 90.7% inhibition were found more effective. Thiophanate Methyl's application significantly reduced the disease severity compared to control plants with disease severity in fungicide-treated trays was 28.7% compared to untreated/control 73.5% and significant increase green and dry fodder weight (931 grams with 92 grams of dry weight) than untreated/control (561 grams with 55 grams of dry weight) in the fourth cut.