In vitro: stem cutting a simple technique for determination aggressive potential of fungal isolates causing root rot disease of grapevine

Abstract

Pathogenic soil borne fungi causing epidemic root rot disease on grapevine and high loss of plant growth and fruit yield. Fast detection of aggressive fungal isolates is the first tool for introduce selection effective a agent for management disease progress. In vitro two simple techniques based on stem cutting of grapevine i.e., mycelial growth and cell wall degrading enzymes activities were evaluated for screening of aggressive fungal isolates in comparsion with classical pathogenicity test. Fourteen isolates of fungi associated with root rot disease of grapevine plants i.e. Fusarium oxysporumi Schlechtend, Fusarium solani (Mart.) Sacc, Botryodiplodia theobromae, Rhizoctonia solani Kuhn and Macrophomina phaseolina (Tassi) Gold. were tested and pathological action on grapevine plant (Cv.crimson) under soil artificially infested by classical method with their mycelial growth,cell wall degrading enzymes activities on stem cutting of grapevine as well as each fungal isolates of shoot and root compare the control. Fungal isolate of Botryiodiplodia theobromae No. (7) was the most isolate recorded high and significant root rot (100%) incidence and disease severity on grapevine plants followed by Fusarium avenacum isolate No. (11) and Fusarium solani isolate No. (12). Positive correlation co-efficient was observed between mycelial growth of fungal isolates tested on stem cutting of grapevine plants and root rot disease incidence and their disease severity followed by their production pectinase and cellulase enzymes. So, mycelial of fungal growth on stem cutting of grapevine is a good and simple of opportunity technique for determination aggressive degrees of fungal isolates in vitro as alternative accuracy, very short time test and very shape cost than classical pathogenicity test.