Michigan State University professor John Wise, right, discusses trunk injection of biopesticides to combat pear psylla at the West Michigan Research Station in Hart on Nov. 1. (Matt Milkovich/Good Fruit Grower)
Michigan State University professor John Wise, right, discusses trunk injection of biopesticides to combat pear psylla at the West Michigan Research Station in Hart on Nov. 1. (Matt Milkovich/Good Fruit Grower)

The West Michigan Research Station has been operating for more than a year, and its research projects are starting to bear fruit. 

The station, a partnership between Michigan State University and a group of growers in West-central Michigan, held a tree fruit field day and pear meeting Nov. 1. Completed last year, the station includes multiple buildings and 68 acres of farmland in Hart, now the home of several asparagus and tree fruit research projects. 

MSU entomology professor John Wise started the pear meeting by discussing different biopesticide application methods to control pear psylla. 

In laboratory settings, biopesticides are often just as effective as conventional pesticides, but they tend to break down more rapidly in an outdoor orchard environment. Ideally, biopesticides should be delivered in a “way that optimizes their performance, as opposed to just throwing it up in the air and walking away,” Wise said.

Wise thought trunk injection might be a more effective way to deliver biopesticides. He’s been studying trunk injection of pesticides for more than a decade, and he started injecting pear trees at the research station in 2021, he said. 

Trunk injection involves piercing a tree’s bark and applying chemicals directly into its vascular system. It’s a technique that was developed for the ornamental and forestry markets but doesn’t yet have a commercial application in tree fruit. Trunk injection is a very effective pesticide delivery method, but the amount of time and labor involved in injecting each tree make it a poor fit in commercial-scale orchards right now, he said. 

“How to make it work for tree fruit production is a really serious challenge that has to be addressed,” Wise said. 

Emily Lavely, MSU tree fruit educator for West-central Michigan, discussed the station’s high-density Bartlett pear planting. The trees are trellised, trained to the tall spindle system, and planted on Amelanchier and quince rootstocks. In the coming years, they’ll evaluate fruit set, scion and rootstock compatibility, fire blight resistance and other factors, she said. 

MSU research assistant Cory Outwater gave an update on the station’s cherry leaf spot trials. In separate blocks, they compared fungicides Bravo and Initiate (chlorothalonil), captan and Kocide (copper hydroxide). Kocide, which they sprayed at 4 pounds per acre instead of the label-recommended 3.5 pounds, was the only product that provided season-long protection. Spraying Kocide at the higher rate provided greater control, though phytotoxicity did lead to some defoliation, Outwater said.

“The important thing is we are holding onto the majority of the leaf,” he said. “So, it might look really ugly early on. But it is controlling the disease.” 

Outwater plans to continue conducting the trials and collect more data next year, he said.

MSU apple production specialist Anna Wallis talked about a new block of apples where they are evaluating alternative trellis materials. The block, Aztec Fuji on Geneva 11, spaced 2.5 feet by 10 feet, has rows with fiberglass and steel posts, testing how well each holds up in high-density orchards. Growers are looking for alternative post materials due to a shortage of pine in the past couple of years, she said.

The jury is still out on the fiberglass posts, which are repurposed from the oil industry. The hollow posts are very flexible and might need to be filled with another material to be strong enough for an orchard trellis, Wallis said. 

The fiberglass posts were difficult to work with, too. The project team had a hard time pounding them into the ground because of their tendency to bend. And in order to keep the wires connected to the posts, they had to drill holes in them, said John Bakker, the station’s interim orchard manager. 

“I’ve done a lot of building,” Bakker said. “I’ve never drilled a material that wears out a drill bit faster than fiberglass.”

Bakker also recommended wearing gloves whenever handling fiberglass posts. 

“I think the final fiberglass slivers just worked their way out of my system about a month ago,” he said. “They were annoying me all summer long.”

The steel posts, designed by TrellX, perform exceptionally well in orchards but are expensive. Wallis said they hope to test concrete and possibly other materials in the future. 

“I think that there’s some good alternatives here,” Bakker said. “But more work needs to be done.” 

—by Matt Milkovich