Disease Development Following Infection of Tomato and Basil Foliage by Airborne Conidia of the Soilborne Pathogens Fusarium oxysporum f. sp. radicis-lycopersici and F. oxysporum f. sp. basilici

Abstract

Fusarium oxysporum f. sp. radicis-lycopersici, the causal agent of Fusarium crown and root rot of tomato, and F. oxysporum f. sp. basilici, the causal agent of Fusarium wilt in basil, are soilborne pathogens capable of producing conspicuous masses of macroconidia along the stem. The role of the airborne propagules in the epidemics of the disease in tomato plants was studied. In the field, airborne propagules of F. oxysporum f. sp. radicis-lycopersici were trapped with a selective medium and their prevalence was determined. Plants grown in both covered and uncovered pots, detached from the field soil, and exposed to natural aerial inoculum developed typical symptoms (82 to 87% diseased plants). The distribution of inoculum in the growth medium in the pots also indicated the occurrence of foliage infection. In greenhouse, foliage and root inoculations were carried out with both tomato and basil and their respective pathogens. Temperature and duration of high relative humidity affected rate of colonization of tomato, but not of basil, by the respective pathogens. Disease incidence in foliage-inoculated plants reached 75 to 100%. In these plants, downward movement of the pathogens from the foliage to the crown and roots was observed. Wounding enhanced pathogen invasion and establishment in the foliage-inoculated plants. The sporulation of the two pathogens on stems, aerial dissemination, and foliage infection raise the need for foliage protection in addition to soil disinfestation, in the framework of an integrated disease management program.

FoSTUA, Encoding a Basic Helix-Loop-Helix Protein, Differentially Regulates Development of Three Kinds of Asexual Spores, Macroconidia, Microconidia, and Chlamydospores, in the Fungal Plant PathogenFusarium oxysporum

“…The timing of symptom appearance and the severity of symptoms were almost the same on plants inoculated with wild-type and mutant strains, indicating that the ⌬FoSTUA mutants retained the abilities to infect host plant tissues and to cause disease symptoms under the conditions tested. F. oxysporum invades from roots of host plants, colonizes roots and stems, and produces conspicuous masses of macroconidia and microconidia on stem surfaces at the late stage of symptom development (26,44,45). We observed mycelia of wild-type and mutant strains growing on stem surfaces 3 weeks after inoculation.…”

“…1D). These asexual spores play important roles in the disease cycle: macroconidia and microconidia are produced on the stem surfaces of infected plants and serve as secondary inocula to spread the fungus to neighboring host plants, and chlamydospores are endurance organs in soil and act as primary inocula when suitable host plants are planted in soil (17,26,39,44,45).…”

Contamination of Fresh Produce by Microbial Indicators on Farms and in Packing Facilities: Elucidation of Environmental Routes

“…Little evidence of correlation was observed in indicator detection and concentration between soil and fresh produce. This is not unexpected, as common regional farming practices (e.g., no nearby animal production facilities, use of synthetic fertilizers rather than compost, and use of plastic mulch), along with the arid growing conditions, likely minimized microbial contamination of soil in this production region (40)(41)(42). Although bivariate correlation analysis (Table 3) suggested that there was a significant negative correlation between microbial-indicator concentrations in irrigation and source water and indicator concentrations on produce, this relationship did not remain after adjustment for any linear model, except that for E. coli on produce and irrigation water (Fig.…”

Short communication: Dieback of rose caused by Acremonium sclerotigenum as a new causal agent of rose dieback in Iran

“…Infection through leaf wounds by airborne propagules of F. oxysporum f. sp. radicis-lycopersici in tomatoes (Rekah et al, 2000) and F. oxysporum f. sp. basilici in basil (Uchida et al, 1996) have also been reported.…”