Good Fruit Grower / January-15th 2012 / Mixup delays ­rootstock production

 Email  Print  Feed

Mixup delays ­rootstock production

Nurseries propagating the new Geneva 214 rootstock found that it was actually the more vigorous G.222.

A mixup in the propagation process will add more than a year to the arrival of quantities of the long-awaited Geneva 214 rootstock, one that is being billed as a superior replacement for M.9.

Last summer, an employee at Willow Drive Nursery in Ephrata, Washington, Richard Adams, noticed that plants in the nursery’s new rootstock stool bed didn’t look right. Genetic testing in September confirmed it was not G.214 but was instead G.222. Adams had been in school at ­Cornell University and was familiar with its Geneva ­rootstocks.

“We caught it early, thank goodness,” said Ken Adams, Richard’s uncle and the president of Willow Drive ­Nursery.

“When he saw the plants, he knew they weren’t labeled right. They have a unique look.

“We don’t know how the mixup occurred, and we’re not sure it’s a big deal. We had planted only a few hundred feet of bed, and we pulled it out quickly. We don’t know how big a loss it will be in time.”

At least three other Washington and Oregon nurseries are in the same position.

The situation is different at North American Plants, the Lafayette, Oregon, nursery, which now has about 300,000 G.222 roots, worth about $1.50 each, and would like to recover its investment. It produced them to distribute to nurseries to use in their stool beds to produce rootstock, thinking they were G.214. The rootstock came to them from Cornell University as plantlets that had been propagated by a tissue culture laboratory in Delphi, New York.

Geneva 222 is a more vigorous rootstock than G.214 and probably not very useful for Willow Drive customers, Adams said.

Geneva 222 has been tested and done well in South Africa, and there may be growers in some areas of the United States who may be interested in it as well, according to ­Cornell horticulturist Dr. Terence Robinson.

“What happened is an embarrassment to us,” Robinson said about the rootstock mixup at the Cornell program. “The best that could come of this now is that some apple growers might see opportunity and use the 300,000 G.222 roots,” he said. “The South Africans love it, and North American Plants has been authorized to offer them for sale. It could be a great one-time opportunity for some growers to get a great fireblight-resistant rootstock.”

What happened?

Dr. Gennaro Fazio, the USDA Agricultural Research Service plant breeder who heads the rootstock development program at Cornell University in Geneva, New York, declined to talk about the mixup, saying he was not authorized to do so. He deferred to the ARS North Atlantic area director, Dariusz Swietlik, who said it was “too sensitive for me to comment.” Yes, there was a mixup, he said.

Nor did Yongjian Chang, the manager at North American Plants, want to talk about it, but did say he was contacting nurseries about selling the G.222 rootstocks, and was resuming production of G.214.

While some have speculated that the mixup could set G. 214 rootstock availability back four to five years, Robinson’s estimate of 14 to 18 months seems more realistic.

Release of four new Geneva rootstocks, including G.214, was announced in late winter of 2010. In the May issue of Good Fruit Grower, Fazio said, “We have the capacity to produce more than a half million trees on Geneva rootstocks every year now, and we’re hoping to reach into the millions in a few more years. We are micropropagating all of them, and six nurseries are licensed to produce liners of Geneva rootstocks. Those six are Copenhaven, Cummins, Treco, Wafler’s, Willamette, and Willow Drive.”

He described G.214 as in the M.9 Pajam 2 rootstock vigor class, highly yield efficient; highly productive (yields of 100 to 125 percent of M.9 in most U.S. trials); with good precocity, cold hardiness, resistance to fireblight, crown rot, and wooly apple aphid, tolerance to replant disease; and having very good propagation characteristics in the stool bed.

Some Geneva rootstocks do not propagate well in the stool bed, having been selected for absence of burr knot and low suckering, but G.214 was not difficult to propagate. It was being developed in tissue culture to obtain greater numbers faster, Robinson said, not because it was difficult to propagate.

Robinson gave a barebones account of the mixup. “We’re not too excited about explaining this,” he said.

Two years ago, when G.214 was officially released, plant material was sent to a tissue culture laboratory in New York State and the first batch was produced, he said. These were DNA tested, under Fazio’s direction, to determine they were G.214 and sent on to be further developed. A second batch, however, was sent on without DNA testing, and these turned out to be G.222.

Not first time

This is not the first time the Cornell University breeding program at the New York ­Agricultural Experiment Station in Geneva has stumbled. According to an article published in Good Fruit Grower in November of 1995, commercial distribution of two new fireblight-resistant rootstocks suffered a major setback because they were not behaving as expecting after being propagated through tissue culture.

The G.65 rootstock, released in 1991 as a very dwarfing (M.27 size) rootstock resistant to phytophthora, fireblight, apple scab, and powdery mildew, turned out to be far more vigorous. G.11, released in 1992 as an M.26 size rootstock with some resistance to ­fireblight, was also more vigorous than expected.

Nurseries that had dug trees on those rootstocks for sale the next spring were advised not to sell them as true G.11 or G.65 trees.

At that time, eight nurseries suffered significant financial losses from growing trees they could not sell. Four to six years of work were lost, as each of the nurseries had used tissue culture to develop thousands of rootstocks starting with one stick of each ­selection.

It was not clear how that mixup occurred. DNA analysis showed that the two rootstocks, after propagation through tissue culture, were not genetically identical to the original rootstocks.