Treatment of leatherleaf fern with benlate systemic fungicide increases populations and virulence of endophytic bacteria
2008
Kloepper, J.W., Dept. Entomology and Plant Pathology, Auburn University, Auburn, USA | McInroy, J.A., Dept. Entomology and Plant Pathology, Auburn University, Auburn, USA
Using molecular techniques, we previously reported that increased populations of Pseudomonas spp. were associated with Benlate use on Leatherleaf fern [2007 Phytopathology 97:S182]. The current study was done to confirm and extend the previous work, using isolation techniques. All Rhizomes of Leatherleaf fern were collected from a commercial fernery in Florida where Benlate was never used. Some rhizomes were planted and grown until three fronds were present on each plant, and these plants were used in a spray experiment containing eight replicate plants of three treatments: Benlate WP, Benlate DF, and water. Other rhizomes were directly used in a drench experiment containing the same three treatments plus a six-hr-old preparation of Benlate DF. In both experiments treatments, all applications of Benlate resulted in significantly greater populations of total bacteria and fluorescent pseudomonads in the rhizosphere, on the rhizome surface, and inside rhizomes 2-4 weeks after application. Benlate treatment also resulted in significantly more deformed root hair tips and in enhanced populations of pseudomonads inside petioles seven weeks after treatment. The percentage of virulent endophytic bacteria, based on testing whole bacterial cells and cell-free metabolites on cucumber, was significantly increased by Benlate. Hence, Benlate changes the microbial community and increases virulence of the community in a perennial plant.
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