Agriculture & Horticulture

Statement of the Problem: Plectosphaerella species have been isolated from different hosts throughout the world such as basil, tomato, sunflower, soybean, cucurbits, pumpkin, endive, rocket, and Lamb lettuce. To date Plectosphaerella genus consists of 12 species such as Pa. alismatis, Pa citrulli, Pa. cucumerina, Pa. delsorboi, Pa. melonis, Pa. oligotrophica, Pa. oratosquillae, Pa. pauciseptata, Pa. plurivora, Pa. populi, Pa. ramiseptata and Pa. sinensis. The most common and known species of Plectosphaerella is Pa. cucumerina, which has been reported as pathogen and endophyte from different horticultural crops as well as biological agent to control of Galium spurium, Sagittaria trifolia and nematodes of potato. Aim: The purpose of this study is to ascertain the role that these fungi play in affected horticultural crops by pathogenicity tests. Methodology & Theoretical Orientation: Nine Plectosphaerella species were artificially inoculated on three different hosts (basil, pepper and tomato) to perform pathogenicity tests in-vitro (detaches lives) and in-vivo (young 30-day old plants) conditions. The pathogenicity tests were carried out in a greenhouse with experimental design consisting of ‘two independent batches’. Each host ×

isolate combination was replicated five times. The disease severities were recorded after 15-35 days after incubation on leaf surface and on roots and collar showing symptoms. Findings: Pathogenicity tests demonstrated that except for Pa. oratosquillae, all Plectosphaerella species essayed in this study are able to cause disease symptoms on all hosts used with different disease severity degrees. Plectosphaerella paucisepatata and Pa. plurivora showed a vascular behavior while the other seven species a parenchymatous behavior. Finally, Pa. ramiseptata resulted to be the most pathogenic species on all the three hosts. Conclusion & Significance: We consider that the Plectosphaerella species investigated in the present study are not endophytic fungi, but pathogenic fungi as they cause necrosis symptoms with different degrees of disease severity.