Efficacy of plant extracts to control fungal post-harvest ROT

Abstract

Fungicides are widely used in conventional agriculture to control plant diseases. Prolonged usage often poses health problems as the modern society is becoming more healthconscious because of their harmful residual effects. The diseases are currently managed with synthetic fungicides but there is, however, a growing global interest on their replacement with other alternatives such as with environment–friendly biopesticides, such as use of botanicals or biological control. Penicillium digitatum, Aspergillius niger and Fusarium Sp, the causal agents of citrus green mold, black rot and brown rot, are important post-harvest pathogens that cause serious losses in citrus annually, besides affections other commercial fruits. The current study tends to the application of botanical as alternative to synthetic fungicides carrying out their antimicrobial screening, longevity study, toxicology, post-harvest study included spraying plant extracts, resident effect, wrapping and coating using different statistical analysis and ANOVA .The research also focus on the selected plant extracts in control post-harvest fruit rot besides the costeffectiveness for commercial purpose .Then selection of the best anti-fungal plant extract on the isolation of its active anti-fungal compound using chromatography analysis. Ten Ethanol extracts(concentrations 500-5000 ppm) of Cerbera odollam L.(Pong-pong), Capsicum frutescence L.(Chili), Azadirachta indica L. (Neem), Cymbopogon nardus L. (Lemon grass), Zingiber officinale L. (Ginger), Andrographis paniculata L . (Green chirayta), Curcuma longa L. (Turmeric), Syzygyum aromaticum L. (Cloves), Murraya koenigii L. (Curry leaf), Swietenia macrophyllai L. (Mahogani), were tested for their antifungal activity for citrus green mold, black rot and brown rot and compared with the control fungicide (Guazatine). Longevity of crude plant extracts was studied depending on their anti-fungi activity under different storage conditions (Refrigerator, Room conditions, and Outside) for four weeks. The best plant extracts were selected of plants under study based their on anti-microbial activity showing more than 70-90% fungal inhibition and longer stability and efficacy under different storage conditions. The toxicity (LC50) of the best anti-fungal extracts was determined by the Brine Shrimp Test (BST). Chromatography analysis GC-MS was used to determine the residual effect in fruits that were sprayed with plant extracts. Efficacy of the selected best plant extract incooperated with biodegradable materials wrappers (Polylactic acid, pectin and newspaper) was determined during storage at room temperature (±25Co) to control fruit-pathogen decay under modified atmosphere packaging (MAP) to increase shelf life and improve the fruit quality and an another experiment in cooperating coating (chitosan, starch and oil paraffin) with fruit wrappers to further increase the fruit quality . The plant extract that exhibited best result to increase the shelf life and fruit quality was subjected to biocompond analysis using chromatography LC-MS. Crude extracts from pong-pong and chili showed fungal inhibition zone in PDA medium at 3000ppm (c.100%), while neem, lemon grass, ginger recorded more than (70%) fungus inhibition; other plants showed low effect less than (50%) for the same concentration. Longevity study showed the fresh extract solution for all plants under study gave best effectiveness of crude plant extracts stored under different conditions. Longevity study of fresh plant extracts under different condition recorded high inhibition in PDA medium for 3 weeks when stored at 4oC, 1 week when stored at 25 oC, and less than 1 week (3days) when samples were kept outside at ±32oC. In vivo, the fruits sprayed with fresh plants extract of neem, pong-pong and chili completely prevented infection at 4000 and 5000 ppm and increased shelf-life of fruit compared with untreated © This item is protected by original copyright xix fruit by three week at room temperature. Five crude plant extracts from pong- pong, chili, neem, lemon grass and Ginger were selected as the best plants based their on antimicrobial activity showing more than 70-90% fungal inhibition and longer stability and efficacy under different storage conditions. LC50 values below 2g/ml are considered to be toxic and unsafe for human consumption. The LC50 values of the plant extracts were: pong-pong was 5μg/ml (low but safe); chili: 20 g/ml (low but safe); neem: 30 g/ml (safe); lemon grass: 473 g/ml (safe) and ginger: 495 g/ml (safe). Mass Spectrometry analyses show low residual effect and not exceed maximum residue limits MRL values in fruit treated with the best extracts after first, second and third week on the spray. Five plants extracts namely pong-pong, chili, neem, lemon grass and ginger incooperated with fruit wrappers fruit showed increased shelf life and decreased weigh loss for fruits stored at room temperature compared with untreated fruit. Plant extract of pong-pong incooperated with coating fruit (chitosan, starch and oil paraffin) showed decreased weigh loss and increased shelf life for fruits stored at room temperature (±25oC) as compared with untreated fruit. Cerebera produced the best results in the experiments and its extract was selected for the identification of active anti-fungal biocompounds from. Alpha Glycoside (4, 6 Benzylidene -1O-Methyl -2O-(2346 Tetra-O-Acetyl-Betad -Glucosyl), a new compound from the leaf extract of Cerebra odollam L. was identified for its antifungal action.