Newly available fruit thinner shows promise in Idaho trials

By Sean Ellis

Idaho Farm Bureau Federation

CALDWELL – Field trials in commercial orchards in southwestern Idaho are proving the effectiveness of a newly available plant growth regulator.

Accede is a product that can be used to thin stone fruit, reducing the amount of labor needed for hand thinning, and can also be used to extend the thinning window in apples and other pome fruit.

The chemical contains ACC, a natural compound responsible for the ripening or maturing of fruit.

Fruit scientist Essie Fallahi pioneered research into the use of blossom thinners for many years while overseeing the University of Idaho’s pomology program in Parma. That initial work was supplemented or completed in other universities.

One of the results of that work – Accede – became commercially registered last year.

Fallahi recently oversaw about 20 test plots for Accede in commercial fruit orchards in the Treasure Valley area of Idaho.

“The results are fantastic,” he told orchardists June 22 during the Idaho State Horticultural Society’s summer field tour. “It is a huge development in the fruit world.”

The orchardists were taken to several of the trial plots.

“This is exciting,” Fallahi said. “With Accede, we are getting rid of inferior fruit and getting more uniformity on the remaining fruit.”

Pretty much all commercial orchards need to use hand thinning but Accede can significantly reduce the amount of labor needed to accomplish that, Fallahi said.

“This is called success,” Fallahi said after pointing out one test plot with significantly less fruit on the branches compared with a nearby plot where Accede was not used. “In here, there is definitely less labor needed.”

Fallahi, president of the American Society for Horticulture Science, told Idaho Farm Bureau Federation that hand thinning is very labor intensive and expensive for orchardists and Accede has shown great promise in helping to reduce that cost.

“Hand thinning is amazingly expensive,” he said. “That is why growers are so excited by this development.”

As an example, Fallahi said it is is common for commercial orchardists to pay about $1,500 per acre for hand thinning of peaches.

“With the use of this fruit thinner, I can’t give you an exact number for what the cost will be because that should be determined by each grower, but I can assure you it will be significantly less,” he said.

For peaches, apricots and nectarines, Accede is used to get rid of blossoms at the bloom stage after pollination or before pollination. With apples, it works as a post-bloom thinner.

Last year was the first year Accede, which is registered for all stone fruit, was tested in commercial orchards in Idaho. The tests were repeated this year.

“The results 90 percent of the time have been fantastic,” Fallahi said. “It is reducing the number of flowers. As a result, it is reducing the number of fruits. And then the remaining fruits on the trees are more uniform and they are larger.”

The results of the active ingredient used in Accede have been published in papers for a number of years based on trials in university plots.

“We wanted to also do trials with commercial growers so they have their own confidence in the chemical and understand how it works,” Fallahi said.

The commercial growers that donated test plots for the commercial trial overseen by Fallahi also helped with labor and materiel costs.

When it comes to commercial fruit, orchardists want fewer fruits per branch because that results in larger sized fruit and more uniformity, which is what the market wants, Fallahi said.

If a branch has too many fruits, they will receive fewer carbohydrates from the leaves and remain smaller, he said. That is why orchardists need to thin a good portion of their crop, in order for the remaining fruit to be larger.

“The less fruit you have, the larger they get,” Fallahi said. “There is a certain leaf-to-fruit ratio that we need in order to have the optimum fruit size.”

One of the test plots for Accede this year was in the Henggeler fruit orchards in Fruitland

In the commercial fruit world, the market pays more for larger fruit, said field manager Chad Henggeler.

“I’d rather have two large peaches than five small ones,” he told Idaho Farm Bureau Federation. “In an over-supplied market, small peaches are very difficult to sell.”

Another test plot was conducted at Symms Fruit Ranch in the Sunny Slope area of Caldwell.

“Conservatively, I’d say (Accede) took off at least a third of the fruit,” co-owner Jamie Hertz told fellow orchardists while reviewing one of the test plots.