Apple maggot (Rhagoletis pomonella) is an insect pest of apple (Malus domestica) that is currently limited in extent in the commercial production areas of Washington State thanks to a quarantine program. We estimate the costs to the Washington economy if this pest were to spread more widely. Apple maggot control costs are related to the pressure of codling moth (Cydia pomonella), the most prevalent insect pest in commercial apple production in Washington State. It was found that the losses for the Washington apple industry’s range from $510 million to $557 million, depending on the codling moth pressure. Our findings underscore the importance of an efficient quarantine program that minimized the risk of spreading the pest along with additional costs associated with quarantined areas.
In the mid-1980s, a statewide educational program was initiated to help improve productivity in replanted apple orchards. This effort began with a study of the background of the problem in Washington and an assessment of the problems growers faced when replanting orchards. An array of potential limiting factors were identified-most important, specific apple replant disease (SARD)-but also low soil pH, poor irrigation practices, arsenic (As) spray residues in the soil, soil compaction, nematodes, nutrient deficiencies, and selection of the appropriate orchard system. The educational program was delivered using a variety of methods to reach audience members with different learning styles and to provide various levels of technical information, focusing on ways to correct all limiting factors in replant situations. Results have been: Acceptance of soil fumigation as a management tool: increased recognition of soil physical, chemical, and moisture problems; reduced reliance on seedling rootstock, and an increase in the use of dwarfing, precocious understocks; and better apple tree growth and production in old apple orchard soils.