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Dave Allan of Yakima is using a similar system to Auvil Fruit Company’s, except that he uses a vertical trellis

Dave Allan of Yakima is using a similar system to Auvil Fruit Company’s, except that he uses a vertical trellis

At Yakima Valley Orchards in Washington, the father-son duo Dave and Travis Allan hope to identify the best way to get a replanted orchard into production, and take some of the guesswork out of it.

In a 14.5-acre block of Honeycrisp planted in 2004, scientists are conducting trials to compare fumigated and nonfumigated trees and evaluate a whole host of rootstocks.

During an orchard replant field day last fall, Dave Allan said that the fumigant Telone C-25 had given more uniform results than Vapam (metam sodium), and the trees grew better. Vapam doesn’t move very well in the soil, and so the ground has to be ripped very well, he said.

In the third leaf, nonfumigated trees were at least two feet shorter than fumigated trees.

Tim Smith, Washington State University Extension educator for north central Washington, confirmed that results with Vapam, which is applied with water, can be variable and said he thinks it’s best to have it applied by professionals. The fumigants Telone C-17 or Telone C-25 are injected into the soil. Smith said Telone (1,3-dichloropropene) alone does not control replant disease, but the chloropicrin in those formulations does.

The Allans installed drip irrigation in the block this year (in the third leaf), but said that in the future they will put a drip system in the first year.

Rootstocks

Fourteen different rootstocks are being evaluated in the block. The trees are spaced 3.3 feet apart with 8.5 feet between rows for a total of 1,550 trees per acre. Budagovsky 9 has been the poorest performing rootstock in the block, Dave reported. At several of his orchards, trees on Bud 9 have gone into decline as they got older.

Tom Auvil, research horticulturist with the Washington Tree Fruit Research Commission, said Bud 9 is usually a good rootstock in virgin ground and has good fireblight tolerance. However, it is not very drought tolerant. “You have to baby it with water,” he said.

Though Mark has a reputation for not being drought-tolerant, some growers are able to manage that rootstock successfully, he added.

Some of the Geneva rootstocks show good tolerance to fireblight and cold hardiness, Auvil said. Geneva 41 produces a Malling 9 size tree and has resistance to woolly apple aphid as well as replant disease and crown rot, but it is not as productive in nursery stool beds as Bud 9 or M.9.

The Honeycrisp trees were planted as sleeping eyes, and the Allans are emulating the training system used at Auvil Fruit Company, Vantage, Washington, except that the trees are trained to a vertical seven-wire trellis, rather than to a V trellis.

This involves keeping branches small and flat on the wires, and not allowing big branches to grow into the alley. Travis said initially they left those branches and paid workers to pull them down, rather than remove them, but it showed a poor return on investment.

Auvil said it’s a waste of green matter to allow vigorous limbs to grow in the wrong places on the tree while trying to establish the canopy. “If you keep vigorous wood out of the bottom of the tree, you’ll get more growth in the top,” he said.

Plantings on such training systems need close and frequent attention, he stressed, otherwise a tree can have big suckers in the lower part while the top looks like it’s going to die.

“Managing the vegetative growth is a long-term endeavor,” Auvil added. “It’s one of the challenges we have in dealing with these high-performance systems. We know what to do, but for whatever reason we’re not able to get it done. If we’re to get the full value of the investment, we need to be here more times. Weed out those limbs when they’re only a few inches long.”

There’s a right time to train the trees and missing that opportunity can create problems that can’t be overcome later, he stressed. “If you allow the limbs to grow up to higher diameter, you’re going to shorten the life and the productivity of the block.”