Root fungi increase the growth and yield and decrease the severity of Fusarium crown and root rot of tomato plants grown in soilless culture (refereed)

This report describes a series of experiments in which three fungal isolates, isolate rf18 of Fusarium culmorum (Smith) Sacc., isolate rf34 of Penicillium brevicompactum Dierckx and isolate rf41 of P. crustosum Thom were examined for their effects on the growth and yield of tomato plants in soilless culture, and on the severity of Fusarium crown and root rot. The three fungal isolates were initially selected on the basis of their ability to increase the growth of tomato seedlings in growth pouch experiments. However, the vegetative growth of small plants (tenth true leaf stage) was not affected by the fungi. In a 1990 yield trial, different fungal treatments resulted in an increase in the weight of immature fruit and an increased efficiency of fruit production (defined as fruit fresh weight per unit plant fresh or dry weight). In a 1991 yield trial, different fungal treatments increased the weight and number of marketable fruit. In growth pouch seedling experiments and two of three small plant trials, some fungal treatments reduced the percent infection and/or severity of infection by Fusarium oxysporum Schlect. f. sp. radicis-lycopersici Jarvis and Shoemaker. However, in the 1991 yield trial, fungal treatments did not affect the infection severity or number of infected plants when a natural epidemic of F. oxysproum f. sp. radicis-lycopersici occurred.