An antiethylene product normally used to slow fruit ripening can also help improve fruit set in cherries, research shows.
Dr. Matt Whiting, cherry horticulturist with Washington State University in Prosser, and Lynn Long, extension educator with Oregon State University, found that applications of ReTain (aminoethoxyvinylglycine) can increase fruit yields in shy-bearing cherry varieties, such as Regina and Tieton. The product is labeled for that use as well as for managing maturity of apples at harvest.
Whiting said lab studies showed that a lack of productivity in certain cherry varieties was related to the flower and not to pollen viability. As soon as the flower opens, the ovule begins to senesce, and it is viable for a shorter time in some varieties than others.
The scientists found that applying a product like ReTain, which reduces ethylene production in the plant tissue, could extend the viability of the ovule.
“By keeping the ovule alive longer, there’s more chance for the pollen to go down and fertilize the flower,” Whiting said.
In their trials with Regina and Tieton, Long and Whiting tested applications equivalent to one pouch (333 grams or 11.75 ounces) of ReTain per acre at four stages during bloom: popcorn, 10 percent full bloom, 50 percent full bloom, and full bloom. They then tested three different rates: half a pouch, one pouch, and one-and-a-half pouches. The product was applied at the equivalent of 200 gallons per acre.
In a trial with Regina in The Dalles, Oregon, the ReTain treatment at 10 percent full bloom gave as much as a 20 percent increase in fruit set compared with the control. That was a gain of almost 9 pounds per tree or 2 tons per acre. Tests with Tieton also resulted in significant increases in fruit set.
Every rate and timing improved fruit set, though there was no consistent trend, which suggests that there’s a broad window when the treatment can be effective, Whiting said. Some of the variability in results might be attributable to the weather at the time of application or immediately afterwards, as warm temperatures hasten the senescence of the ovule.
Whiting suggests using one or one-and-a-half pouches per acre. He said the product is expensive, but the indications are that there could be a very positive return on investment. It costs around $280 to $300 per acre at a one-pouch rate.
“You need to figure out how many additional fruit per tree you need to make it work,” he said.
The research was funded by the Oregon Sweet Cherry Commission. •