IFTA Day 3: Pennsylvania by boardroom

Michigan State University extension specialist Anna Wallis discusses chemical thinners at the International Fruit Tree Association’s annual conference in Pennsylvania on Feb. 15. (Matt Milkovich/Good Fruit Grower)

The third and final day of the International Tree Fruit Association’s 65th Annual Conference and Tours, held in Hershey, Pennsylvania, was a full day of educational sessions.

Jim Schupp, professor of pomology at Penn State University, spoke about rootstocks for future peach production. He said peaches are the second most important tree fruit in Pennsylvania, after apples, and are very important for early season cash flow.

However, low yields are a challenge and production efficiency is lower than for apples. Current low-density fishing systems are slow to initiate cultivation, with suboptimal cultivation potential.

Peach trees are also labor intensive, with very dense canopies and excessively vigorous regrowth. Shade reduces fruit quality and color, and typical vase-culture systems are not compatible with mechanization, he said.

In other words, Pennsylvania peach farmers aren’t ready for the future and they need to make some changes. Among other things, they need higher densities for earlier and larger yields, tight canopies, and size-controlling rootstocks.

One of the drive systems recommended by Schupp was the Quad V, which splits the canopy into two narrow tree walls. The system increases yield and color and facilitates mechanization. It can also handle crop load, irrigation and fertilizer better, Schupp said.

He said Bailey was a good rootstock for earliness, productivity and size control. Controllers 6, 7 and 8 also showed promise as productive semi-dwarf rootstocks in his peach tree trials.

Schupp said dwarf peach trees need permanent support, such as trellises and posts.

“There is no full, self-contained dwarf tree in a commercial setting,” he said.

High-density peaches won’t be the same as high-density apples: They’ll need slightly wider spacings to achieve better fruit size, he said.

“We are overdue for a step change in peach production systems,” Schupp said.

Retired Rutgers University agricultural officer Win Cowgill led the afternoon session, titled “PGR, Biostimulants, and Snake Oils.”

So what makes a product real and not “snake oil”? Cowgill said good replicated research from a third party is a good indicator. A company must be prepared to put its products to the test. What’s wrong is a product that’s only backed by customer testimonials. If a product developer is unwilling to invest money in product testing and development, chances are the product is snake oil, he said.

Valent’s technical development specialist, Poliana Francescatto, opened a discussion on plant growth regulators by talking about ACC and ABA. ABA, abscisic acid, is a natural plant hormone that promotes the thinning of apples and especially pears. It can be used in organic production and has potential for bitter pit control in apples.

ABA, which promotes leaf senescence and abscission, could be used to partially defoliate apple trees to promote fruit color, she said.

ACC, marketed as Accede, is the first approved stone fruit thinner based on a natural compound. An immediate precursor to ethylene, ACC can be applied from pink bud to petal fall in stone fruits and could be a late/rescue thinner in apples. ACC is a more reliable fruit diluent than ethephon at high temperatures, and it does not cause gummosis in stone fruits, Francescatto said.

Anna Wallis, an apple production specialist at Michigan State University Extension, said that a first application of Accede to peaches at 20% bloom and a second application at 100% flowering can lead to a significant reduction in fruit, reducing hand thinning by almost half.

As an apple thinner, Accede works best as part of a season-long thinning program. In the Michigan trials, Accede performed best on apples in the “backup” thinning window, when fruit is about 20 millimeters in diameter, Wallis said.

by Matt Milkovitch

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