5.2.2S
POST-HARVEST BIOLOGICAL CONTROL: COMMERCIAL SUCCESSES AND A MODEL FOR PUBLIC AND PRIVATE-SECTOR COOPERATION

JP STACK

University of Nebraska, SCREC, Clay Center, NE 68933, USA

Background and objectives
In 1997, over eight million pounds of pears (ca 75% of pears going into storage) from the Pacific Northwest were treated with Bio-Save 110 and eight million pounds of oranges and lemons in California were treated with Bio-Save 1000 to prevent post-harvest decay during storage. The Bio-Save product line (EcoScience Corporation, New Brunswick, NJ, USA) has been in commercial use for 3 years in the USA with EPA labels for pome and citrus fruits. It is estimated that in 1998 more fruit will be treated with Bio-Save than has ever been commercially treated with any biological control product. Bio-Save offers excellent protection against the major post-harvest decay pathogens of pome fruits (i.e. Penicillium expansum, Botrytis cinerea and Mucor piriformis), and citrus, (i.e. Penicillium digitatum, P. italicum and Geotrichum candidum). In 1997, a label extension was granted for the use of Bio-Save 1000 to protect cherries from certain post-harvest decay pathogens; it will be used commercially in 1998.

The discovery, development and commercialization of the Bio-Save products required the cooperation and interaction of many individuals representing industry, government (USDA, EPA), and academia. The active ingredient of Bio-Save 1000 and Bio-Save 100 (Pseudomonas syringae strain ESC10) was discovered and developed by EcoScience Corp. The active ingredient of Bio-Save 110 (Pseudomonas syringae strain ESC11) was discovered and initially characterized by Dr Wojciech Janisiewicz with the USDA (Kearneysville, WV, USA); EcoScience licensed the rights to commercially develop ECS11. During the early product development stage, University and USDA scientists collaborated with EcoScience to conduct small-scale efficacy testing and non-target risk assessment. Industry labs with expertise in production of microbials collaborated with EcoScience to develop cost-effective and stable methods of production and formulation. During advanced stages of development, the fruit packing industry worked closely with EcoScience to facilitate the adoption of biologically-based technology. Throughout, the EPA helped EcoScience work through the regulatory process. The successful introduction of Bio-Save to the market was the result of the collaboration of many individuals and institutions. At present, Bio-Save 150 (active ingredient Cryptococcus laurentii, discovered by Dr Rodney Roberts, USDA, Wenatchee, WA) is under development following the same cooperative model.

Results and conclusions
Most post-harvest decays of pome and citrus fruits are caused by opportunistic pathogens requiring a wound for entry. Consequently, the primary screen for potential biocontrol agents included the ability to colonize wounds and prevent decay. Strains of P. syringae were identified with the ability to colonize wounds of pome and citrus fruits while providing excellent protection against the most common wound pathogens. While declining on the fruit surface, ESC10 and ESC11 persisted in wounds of fruit in cold storage (e.g. 10C, natural atmosphere) or modified atmosphere storage (e.g. 0.5C, 6% CO2). A frozen pellet formulation (83% active ingredient) was developed with sufficient shelf stability to meet packhouse industry requirements. Under commercial packhouse conditions, Bio-Save 1000 (lemons, oranges, and grapefruits), Bio-Save 100 (apples), and Bio-Save 110 (pears) consistently protected fruit from postharvest decay; in most cases efficacy was comparable to the industry standard synthetic fungicide. The mechanisms of biological control appear to be competition for space and nutrients. Several experiments in different laboratories have failed to identify antibiotics as the basis of efficacy. Bio-Save is used as a stand alone product to prevent decay. Equally important, it is also used as a tool in the management of fungicide-resistant isolates of decay pathogens.

References
1. Stack JP et al., 1992. Phytopathology 82, 1063
2. Janiciewicz and Jeffers, 1997. Crop Protection 16, 629-633
3. Bull et al., 1997. Biological Control 8, 1-88.