Treatments to make tart cherries export-ready

As Michigan tart cherry growers grapple with stiff competition from imported products, researchers are exploring how export markets could provide a valuable path forward. While demand abroad may offer new opportunities, reaching those markets requires growers to meet a complex set of standards that often differ significantly from those in the U.S. Among the biggest challenges are stricter maximum residue limits (MRLs) for pesticides and concerns about pest contamination, particularly from spotted wing drosophila (SWD).

A Michigan State University research team led by Jackie Perkins, Emily Lavely, Heather Leach, Winter Krajci, Reillyn Ford and Ashlyn Clement is working to help growers navigate those hurdles. Their project focuses on developing pest management programs that protect fruit quality while also satisfying export requirements.

The team’s first objective was to evaluate how current tart cherry pest management programs perform when measured against both pest control needs and the residue requirements of potential foreign markets. Researchers aimed to identify where existing spray programs may need adjustment to better align with export expectations.

A second objective centered on testing modified programs to determine whether they could continue providing reliable pest control while improving compliance with export standards. Findings from the project will ultimately support the development of Extension resources and educational programming for growers.

The researchers conducted extensive monitoring during the 2024 and 2025 growing seasons. Weekly trapping of SWD was carried out at 14 cherry orchards located across southwest, west-central and northwest Michigan production regions. The monitoring effort provided a broad snapshot of pest pressure across the state’s major growing areas.

Two weeks before harvest, fruit samples were collected from each orchard to assess SWD infestation levels. These evaluations helped researchers determine how effectively current management programs were protecting fruit from infestation as harvest approached.

Residue testing was another key component of the study. From each participating farm, researchers collected 10 one-pound fruit samples after cherries had spent two hours on a cooling pad. The team also gathered fruit from tart cherry processors during both years of the project, focusing primarily on quick-frozen products. These samples provided additional insight into residue levels present in commercially processed fruit.

In 2025, the researchers expanded their efforts through a spray trial at the West Central Michigan Research & Extension Center in Hart. They evaluated four different pre-harvest treatment programs targeting SWD. Before harvest, fruit were assessed for Drosophila larvae infestation to compare treatment performance. The research team also collected fruit on the day of the label-directed pre-harvest interval as well as one day later. This allowed them to determine whether a slightly longer waiting period before harvest could help reduce pesticide residues enough to satisfy export requirements.

Results from the study underscored the delicate balance between pest protection and market access. Heavy insecticide use leading up to harvest remains the most significant obstacle to exporting Michigan tart cherries. Effective management of SWD often requires intensive insecticide programs and some of the products commonly used by growers create residue concerns in export markets.

One product in particular emerged as a recurring challenge. Imidan®, which is widely used for SWD management, was frequently detected at levels exceeding MRL requirements in potential export destinations. Researchers also found that extending harvest by an additional day after the final Imidan application did not sufficiently lower residue levels to meet those standards.

Several alternative products produced more encouraging results. Mustang® Maxx, Danitol® and Exirel® remained effective tools for controlling SWD while avoiding potentially problematic residue levels.

Grandevo® and Entrust® also showed promise as low-residue options. However, researchers noted that these products can be expensive and may be difficult to justify during seasons marked by severe pest pressure.

Disease management programs presented far fewer concerns. Fungicide residues did not exceed MRL thresholds during either year of the study, suggesting that current disease control practices are unlikely to limit export opportunities for Michigan tart cherry growers.

Looking ahead, the MSU team plans to continue analyzing spray records, scouting information and economic factors associated with alternative management programs. A cost-benefit analysis will help refine future recommendations and support the development of practical Extension resources.

As growers search for fresh markets and stronger returns, building export-ready pest management programs may become an increasingly important piece of Michigan’s tart cherry future.

by Enrico Villamaino