Evaluating eco-friendly botanicals (natural plant extracts) as alternatives to synthetic fungicides.

BACKGROUND

Fungicides are widely used in conventional agriculture to control plant diseases. Prolonged usage often poses health problems as modern society is becoming more health-conscious. Penicillium digitatum, the cause of citrus green mould, is an important postharvest pathogen which causes serious losses annually. The disease is currently managed with synthetic fungicides. There is, however, a growing concern globally about the continuous use of synthetic chemicals on food crops because of their potential effects on human health and the environment.

METHODS

Different concentrations (500-5,000 ppm) of 5 ethanol extracts of Neem, Pong-pong, Chili, Lemon grass, and Ginger were compared with DMSO and fungicide (Guazatine,1,000 ppm) for their anti-fungal activity (inhibition zone) in vitro on PDA media and during storage conditions. Lethality test LC50 (BST) was followed to determine the lethal dose from plant extract compared with the lethal dose for synthetic chemicals (Guazatine).

RESULTS

Crude extraction from Neem, Chili and, Pong-pong showed a complete inhibition zone at 3,000ppm (100%) in the green mould in vitro. At in vivo, concentrations (4,000 and 5,000ppm), Neem, Chili, and Pong-pong showed a high effect on the prevention of the development of mycelia growth Penicillium digitatum on the surface fruits in storage conditions at 25 °C±2. In addition, the lethal concentration (LC50) values of the crude extracts were investigated by using the Brine-shrimp (Artemia salina Leach) lethality test (BST). At 20.5 and 30 μg/ml-1, Neem, Pong-pong and hot Chili showed very high lethal toxicity on brine and effect. Lemon grass and Ginger killed 50% at 495 and 473 μg/ml(-1), respectively, compared with controls.

CONCLUSIONS

Pong-pong, Neem, and chili showed positive effects on the inhibition of postharvest fungi as alternatives to fungicides, while bearing in mind the increasing global pollution of the environmental. Extracts from Lemon grass and Ginger have interesting antifungal activity and they are also toxic in bioassay against shrimp. These extracts or botanicals have a bright future in modern plant protection to replace conventional synthetic pesticides.