Optimizing the efficacy and environmental fitness of a commercial Pseudomonas bacterial biocontrol product for the control of turfgrass disease

A fungicide/antibiotic-producing bacterial strain of Pseudomonas aureofaciens Tx-1 (Tx-1) has been commercialized for golf course use with some success in recent years. To achieve adequate control it must be applied daily. This may be partially explained by UV susceptibility of Tx-1, which is a common limitation of biocontrol agents. Results from various wavelengths of ultraviolet radiation (A, B, C) exposure tests showed a significant drop in Tx-1 survivors following increased dosage. Significant improvement of UV tolerance was achieved and demonstrated in all UV exposure tests by mixing a sunscreen. In an attempt to identify the most UV-resistant individual cells, Tx-1 was exposed to intensive UV light (UV-C) for various lengths of time (in vitro). Cells (10TC30) with significantly improved survival rate after 7 J/m2 UV-C irradiation was found followed by 10 cycles of 42 J/m2 of UVC exposure. Field data of dollar spot and anthracnose control studies showed that applied at high concentration (107CFU/cm2), Tx-1 sunscreen mixture and the strain 10TC30 provided significant disease control compared with non-treated control in the field study. Population sizes of the treatments were monitored, and results demonstrate the improved percentage of survival of Tx-1 with the protection of sunscreen...