Evaluation of Fungicides and Fungicide Application Methods to Manage Phytophthora Blight of Pigeonpea

Abstract

Phytophthora, a blight of pigeonpea caused by Phytophthora cajani, has been significantly increasing in major pigeonpea production regions of India. Limited information on infection with this pathogen and its epidemiology, as well as a lack of adequate resistant cultivars, is hampering the management of Phytophthora blight significantly. Therefore, five fungicides, viz., metiram + dimethomorph, cymoxanil + mancozeb, famoxadone + cymoxanil, mancozeb, and metalaxyl-M + mancozeb, were evaluated against P. cajani under control conditions to control zoospore induction, as well as the infection of zoospores, at the seedling stage. The half-maximal effective concentration (EC50) of fungicides for mycelial inhibition was calculated. The lowest EC50 was recorded in metiram + dimethomorph (0.17 µg/mL), followed by the metalaxyl-M + mancozeb (2.49 µg/mL) and cymoxanil + mancozeb (8.23 µg/mL) fungicides. The formation of the sporangium and zoospores was most significantly affected by metalaxyl-M + mancozeb, followed by metiram + dimethomorph and cymoxanil + mancozeb, in terms of sporangia viability and zoospore germination and encystment. Further, under glasshouse conditions, different fungicide application methods (e.g., seed-treatment; soil-drench; foliar-spray, either singly or in combinations) were evaluated with fungicides on susceptible (ICP 7119) moderately resistant pigeonpea (ICPL 99010, ICPL 20135 and ICPL 99048) cultivars. The seed-treatment + soil-drench, soil-drench + foliar-spray, and soil-drench of fungicide application methods were found to be effective in controlling the Phytophthora blight, at p < 0.001. A combination of the seed-treatment + soil-drench and soil-drench + foliar-spray methods, using metalaxyl-M + mancozeb or metiram + dimethomorph fungicides on moderately resistant cultivars (ICPL 99010), has a synergistic effect on the ability to control the Phytophthora blight at the seedling stage.

Inhibitory Effects of Endemic Thyme's Thymol‐Carvacrol Chemotype Essential Oil on Aspergillus Species with Free Radical Scavenging Properties

“…As per the definition, the minimum inhibitory concentration (MIC) and half‐maximal effective concentration (EC 50 ) are usually determined through laboratory assays that involve testing various concentrations of the fungicide against the targeted fungus. The assays were performed under controlled conditions to ensure accurate and consistent results [41] . In this context, we conducted literature comparisons between our essential oil and synthetic fungicides to support our data.…”

Phytophthora capsici the Causal Agent of Phytophthora Blight of Capsicum spp.: From Its Taxonomy to Disease Management

“…Extensive laboratory and field trials have demonstrated the effectiveness of these synthetic Oomyceticides (Wang et al, 2020). For instance, Mancozeb 64% + Metalaxyl 4%, Copper sulfate pentahydrate (soil application) and Potassium phosphonate (foliar application) can completely eliminate root and crown rot (Sharma et al, 2023). Additionally, Fosetil Aluminum (soil drench) has been shown to reduce wilting in pepper plants by 100%.…”

“…IDM strategies should be integrated within agroecological, ___________________________________________________________________________________________ conventional, or other production systems, as a single approach often proves insufficient. By combining these strategies, IDM aims to achieve effective and sustainable control of P. capsici in Capsicum crops (Liu et al, 2019;Ngo et al, 2020;Hua et al, 2022;Muthu Narayanan et al, 2022;Tiwari et al, 2022;Acharya et al, 2023;Quesada-Ocampo et al, 2023;Santos et al, 2023 andSharma et al, 2023).…”

“…The staggering $100 million in annual losses attributed to P. capsici makes it the world's fifth most destructive Oomycete (Kamoun et al, 2015). Its ability to reach aerial plant tissues and 2 ___________________________________________________________________________________________ its polycyclic nature further complicate management strategies, solidifying its reputation as one of the most challenging plant pathogens to control (Santos et al, 2023 andSharma et al, 2023).…”