Phytochemical screening and assessment of various weed extracts for the management of Alternaria solani infecting Solanaceous crops

One of the major diseases of Solanaceae family is early blight caused by Alternaria solani which lowers the yield with reduction of plant health and seed quality. The current study assessed the presence of secondary metabolites in the extracts of selected weeds such as Cannabis sativa, Parthenium hysterophorus, and Lantana camara using phytochemical screening and their antifungal interactions with the target pathogen Alternaria solani. The results of phytochemical screening showed that P. hysterophorus was particularly rich in amino acids, which were not found in the aqueous and ethanol extracts of C. sativa and L. camara. Proteins were detected in all extracts except those from P. hysterophorus. Tannins were absent only from L. camara, but present in the other extracts. P. hysterophorus also had a substantial amount of flavonoids, which were absent from the ethanol extract of L. camara but present in other extracts. Phytosterols were found in every extract of C. sativa, L. camara, and P. hysterophorus. Food poison method and Agar disc diffusion method were used to investigate the antifungal behavior of weeds extracts against Alternaria solani. The food poison method produced significantly better results than the agar-disc diffusion method. However, the order of effectiveness of weeds using these two methods were: C. sativa > L. camara > P. hysterophorus. Moreover, maximum inhibition was observed in the aqueous extract of C. sativa after seven days of incubation. The outcomes of this study could lessen the need for artificial fungicides and aid in controlling the emergence of disease resistance and hold substantial significance in the realm of sustainable agriculture and disease management.