natural-products-in-plant-pest-management

Natural Products from Plants 67in plants. The efficacy of crude, boiled water and acetone extracts of 17 plantspecies against Rhizoctonia solani, causing wet root rot disease in chickpeas,was evaluated under laboratory conditions (Kane et al., 2002). The crude,boiled water and acetone extracts of A. sativum, the crude and boiled waterextract of Eucalyptus sp., as well as the boiled water and acetone extracts ofZingiber officinale contributed to 100% inhibition of the mycelial growth of thepathogen. In the same year Prabha et al. (2002) reported on the antifungalproperties of extracts from Foeniculum vulgare, Coriandrum sativum, Trigonellafoenum-graecum, Anethum graveolens and Cuminum cyminum against threefungi, including Fusarium oxysporum. All extracts showed a relatively greaterinhibitory effect on F. oxysporum, with stem extracts from A. graveolens exhibitingcomplete growth suppression, while the mycelial growth of the othertwo fungi was also inhibited significantly.Om et al. (2001) also reported the effect of essential oils extracted fromCallistemon lanceolatus (Callistemon citrinus), Citrus medica, Eclipta alba, Hyptissuaveolens and Ocimum canum (O. americanum) against Rhizoctonia solani, thecause of damping-off disease of tomato and chilli (Capsicum annuum). Theessential oils of Citrus medica, E. alba and O. canum completely inhibitedthe growth of the fungus within 24 h. The essential oils of C. lanceolatus andO. canum controlled the damping-off disease of tomato by 57 and 71%and that of chilli by 40 and 83%, respectively. The same effect was alsoobserved by applying crude, boiled water and acetone extracts fromA. sativum, and a boiled water extract of Eucalyptus sp., as well as boiledwater and acetone extracts of Zingiber officinale (Kane et al., 2002).In some cases plant extracts not only inhibit fungal mycelial growth, butalso spore germination. Chen et al. (2002) reported that Chloris virgata, Dalbergiahupeana, Pinus massoniana, Paeonia suffruticosa and Robinia pseudoacaciaextracts inhibited spore germination of grape downy mildew (Plasmoparaviticola) and the effect was comparable to that of a traditional fungicide, liquidBordeaux. Other work also demonstrated that leaf extracts of Lawsoniainermis and Datura metel possess antifungal activity against Mycosphaerellaberkeleyi, causing late leaf spot in groundnuts (Kishore et al., 2002). Particularly,the D. metel extract continuously reduced disease progress up to 115days after sowing while the severity of late leaf spot at harvest wassignificantly less than that of the controls.Plant seeds also contain compounds with antimicrobial properties. Seedextracts of 50 plant species, belonging to different families, were evaluatedfor their ability to inhibit the growth of Trichoderma viride in vitro (Bharathimathaet al., 2002). Of the various seed extracts, that of Harpullia cupanioides(Roxb.), belonging to the family Sapindaceae, displayed very high antifungalactivity. The seed extract of H. cupanioides strongly inhibited the growth ofRhizoctonia solani, Curvularia lunata (Cochliobolus lunatus), Colletotrichum musaeand Alternaria alternata and retained its antifungal activity even after heatingat 100°C for 10 min or autoclaving at 121°C for 20 min. Rodriguez and Montilla(2002) reported on the in vitro and in vivo antimicrobial effect of a Citrusparadisi seed extract (Citrex) on F. oxysporum lycopersici causing tomato wilt.Five treatments were evaluated: (i) immersion of plant roots in a solution of