IOSR Journal of Agriculture and Veterinary Science (IOSR-JAVS) e-ISSN: 2319-2380, p-ISSN: 2319-2372. Volume 10, Issue 4 Ver. I (April. 2017), PP 49-57 www.iosrjournals.org DOI: 10.9790/2380-1004014957 www.iosrjournals.org 49 | Page In vitro Antifungal Activity of Some Plant Extracts against Seed-borne Pathogens F. A. Abushaala 1 , A. R. Ben Ramadan 1 , M. A. S. Fahej 2 1- Microbiology Department, Faculty of Science, Misurata University, Libya 2- Biology Department, Faculty of Science, Elmergib University, El-khums, Libya. Abstract: Chemical fungicides cause serious environmental problems. Plant metabolites and plant based pesticides considered to be better alternatives as they are known to have minimal environmental impact in contrast to synthetic pesticides. In this study some plant extracts in different concentrations were tested in vitro for their activity against some cucurbit seed-borne fungi. All tested plant extracts significantly reduced the growth of the tested damping-off pathogens at all tested concentrations. F. semitictum and F. solani were more sensitive to plant extracts treatment than the other tested pathogens, where R. raetam extracts with 15% and 10% concentrations as mean were more effective to tested damping-off pathogens, whereas R. raetam 5% concentration and P. dactylifera 15% concentration were similarly efficient in suppression (30.0 and 30.2 mm, respectively). C. trifurcatum gave lowest effect, whereas P. dactylifera 5% and C. trifurcatum 15% gave the equal values (27.2%). The highest inhibitory zone values were obtained by the plant extract R. raetam (32.53 mm as a mean values). F. solani, F. semitictum and F. moniliforme were more sensitive with the highest inhibitory zone values due to plant extract treatments (37.0, 36.0 and 36.0 mm, respectively). Keywords: Damping-off pathogens, Plant extract, Cucurbit seed-borne fungi, Antifungal activity. I. Introduction Cucurbits are important vegetable crops that daily consumed world over. The family cucurbitaceae, includes cucumber (Cucumis sativus), squash (Cucurbita pepo), watermelon (Citrullus lanatus), cantaloupe (Cucumis melo var. cantaloupensis), snak cucumber (Cucumis melo var. flexuosus), sweetmelon (Cucumis melo) and pumpkin (Cucurbita sp.). Serious soil-borne and seed-borne pathogens, i.e. Pythium debaryanum, P. ultimum, P. dissotocum, P. oligandrum, P. violae, P. aphanedermatum, Macrophomina phaseolina, Rhizoctonia solani, Fusarium solani, F. semitectum, Aphanomyces euteiches, Sclerotinia sclerotiorum and many species of Verticillium and Cladosporium., can cause damping-off and root rot diseases, resulting in great economic losses in crop yield and quality. The use of fungicides for control of these pathogens has met moderate success and their future use is in question due to increased regulatory restrictions. So, the modern approach in plant disease control is directed toward minimizing the fungicidal use to decrease environmental pollution and finding alternatives to chemical fungicides. Hence, in recent time application of plant extracts as well as plant metabolites for plant disease management has become important viable component of Integrated Pest Management, as plant metabolites are eco-friendly where botanicals place an important role (Sahayaraj et al., 2009). Several investigation studies have been conducted in order to screening different plants for their antifungal properties (Stephan et al., 2005 and Satish et al., 2010) and biochemical compounds that these plants have. Studies revealed a highly significant antifungal activity of some water extracts or essential oils of plants. Since some plants are already known to possess several biological activities (Amin et al., 2009 and Belabid et al., 2010). 1. Plant extracts: The antimicrobial activity of secondary metabolites and lectins, compounds usually associated to defense mechanisms of plants. Secondary metabolites are separated into nitrogen compounds (alkaloids, non- protein amino acids, amines, alcamides, cyanogenic glycosides and glucosinolates) and nonnitrogen compounds (monoterpenes, diterpenes, triterpenes, tetraterpenes, sesquiterpenes, saponins, flavonoids, steroids and coumarins). Lectins are carbohydrate-binding proteins and their biological properties include cell-cell interactions. This chapter reports solvent organic extracts (mixture of secondary metabolites), isolated secondary metabolites and lectins from plants with antimicrobial activity against Gram-negative and Gram-positive bacteria as well as antifungal activity towards human and plant pathogens. Effects of plant secondary metabolites and lectins on deleterious human and plant microorganisms indicate their perspectives of antimicrobial uses (Paiva et al., 2010). Solvent organic extracts contain a mixture of secondary metabolites including alkaloids, flavonoids, terpenoids and other phenolic compounds; these molecules are associated to defense mechanisms of plants by their repellent or attractive properties, protection against biotic and abiotic stresses and maintenance of structural integrity of plants (Tepe et al., 2005).