Abstract
The present studies were conducted to evaluate the efficacy of botanical extracts (neem, mint, turmeric and ginger) and salicylic acid on disease incidence and associated physiological and biochemical parameters against anthracnose disease in commercially available guava variety Allahabad Safeda. Three foliar applications of botanical extracts prepared from mint leaf (10, 20 and 30 gL− 1), neem leaf (10, 20 and 30 gL− 1), turmeric rhizome (5, 7.5 and 10 gL− 1), ginger rhizome (5, 7.5 and 10 gL− 1) and salicylic acid (5, 10 and 15 mgL− 1), were applied to the guava trees during flower bud appearance (mid-May), fully opened sepals (end of May) and 50% opened bloom stage (mid-June). Percent disease index (PDI) and physio-biochemical attributes were assessed at 30 DAS, 60 DAS and 90 DAS during 2022 and 2023. Neem @ 30 gL− 1 reduced the incidence of the disease to 11.52 per cent in the infected guava fruits as compared to the untreated control (31.53 per cent) and emerged as most effective against anthracnose. All other treatments at their highest concentration controlled the disease incidence in the guava fruits. Neem leaf extract @ 30 gL− 1 resulted in higher photosynthetic pigments, total soluble sugars, total soluble proteins, free amino acids, antioxidants (ascorbic acid, proline and α-tocopherol content) and lowered H2O2 and malondialdehyde content; with higher activities of peroxidase and polyphenol oxidase enzymes as compared to untreated control. The organic acid and salicylic acid content was higher in the peels of fruits taken from trees treated with botanical extracts. This study can be further used to decipher the underlying molecular mechanism during anthracnose infection in guava and to further promote the green management strategy to reduce this disease.