Induction of Systemic Resistance Against Tomato Root Rot Disease Under Greenhouse Conditions

Induction of systemic resistance against tomato root rot is considered save and goodstrategy for controlling this serious disease which lead to delay growth and death of severely infectedplants especially under protective production. Sixteen isolates of Rhizoctonia solani and ten ofFusarium solani were isolated from diseased tomato samples collected from ten Egyptiangovernorates. The isolated fungi were differed in their virulence on tomato plants. Kafr-El-Sheikhisolates No.16 of R. solani and Gharbia isolate No.8 of F. solani were significantly more aggressivethan the others. All tested antagonistic treatments including bioagents, biocides, chemical inducers andplant oils as well as Vitavax-200 significantly reduced the disease severity under greenhouseconditions. The results also revealed that dipotassium hydrogen phosphate at 2% concentration, Bio-Arc and Bio-Zeid at recommended doses recorded the least disease severity caused by the isolatedpathogens, followed by Trichoderma koningii (14), T. harzianum (15) and Acinetobacter genospecies(B40). Other treatments were less effective. Soaking roots of tomato seedling for two hours in most ofbiotic and abiotic inducers before transplanting in soil infested with the pathogenic fungi increasedperoxidase, polyphenol oxidase and chitinase activities at 14 days post inoculation (dpi) to valuesmore than 7 dpi.