Synergistic effect of plant extracts and fungicide against purple blotch disease of onion

Abstract

Onion is widely cultivated crop and attacked by different fungi. Purple blotch of onion caused by Alternaria porri is a continuous threat to Pakistan agriculture industry for the last few years. Generally, fungicides give satisfactory control but due to the environmental concerns, their use should be restricted. In integrated disease management program, cost effective and eco-friendly approach is used to cope with plant pathogens. Therefore, the present study was planned to evaluate the antifungal efficacy of different plants extracts such as Pongamia pinnata, Polyalthia longifolia, Cassia fistula, and Citrus sinensis against A. porri alone as well as synergistically with different concentrations of Mancozeb under in vitro conditions. Methanolic leaves extracts of these plants were mixed with different concentrations (25, 50, and 75%) of fungicide and screened via poisoned food technique to measure percent inhibition of fungal growth. The results indicated that plant extracts alone gave appreciable amount of fungal reduction but when used in combination with fungicide, performed best. Among them P. longifolia gave 73%inhibition, C. sinensis 49%, P. pinnata 70%and Cassia fistula showed46% inhibition respectively. In combination with fungicide, 25% of recommended dose, P. longifolia gave 82.93%, P. pinnata gave 77.07 %, C. sinensis 73.17% and C. fistula gave 62.92% inhibition as compared to control against A. porri. With the increase of fungicide in combination, more reduction in the fungal growth was observed. It is concluded that extracts can be used synergistically with fungicides. The combinations will protect the environment by reducing the amount of fungicide

Identification of Alternaria spp. associated with purple blotch disease in onions and evaluation of plant-based fungicides for disease control

“…However, in the absence of genetic resistance in crops, crop production relies on the use of synthetic chemicals (Mandi et al, 2020;Ravikumar et al, 2020). Despite their effectiveness, synthetic chemicals have deleterious consequences on the environment, increase residual toxicity levels in produce, and tolerance among pathogens to fungicides (El-Mougy & Abdel-Kader, 2019; Kalsoom et al, 2019). Currently, no resistant source is available against purple blotch of onion due to genetic variations or divergence among pathogen populations.…”

Activity of extracts from selected Tanzanian spices on major fungal pathogens and blight diseases of Tomato

“…Some studies have further recommended use of botanical extracts with the recommended fungicides but at lower concentrations. A combination of extracts from Polyalthia longifolia with 25% of the recommended fungicide, mancozeb, for controlling purple blotch reduced the growth of Alternaria porri by about 82% (Kalsoom et al, 2019). This combination of botanical extracts with fungicides is to support reduced usage and reliance of synthetic pesticides (Deepa et al, 2013).…”