When the manager of an orchard at Manson, Washington, told grafter Ken Coates that he was thinking of pulling out an Amber Jewel plum block to plant cherries, Coates told him he had a better plan.

Coates, who has been a commercial grafter for almost 30 years, had experience in California of using an interstem to graft plums over to cherries instead of pulling the trees, thereby avoiding the costs and lost time involved in replanting.

For the interstem, he uses the plum rootstock Adara, which is compatible with cherry. Adara (Prunus cerasifera) was developed in Spain and is sometimes used as a cherry rootstock in California.

The plum trees at the Manson orchard are on Citation rootstocks and trained to a four-wire trellis. "You can imagine the cost of taking this orchard out, and buying new trees, and preparing the ground, and possibly ­redoing the irrigation," Coates said.

In spring of 2008, he grafted pieces of Adara wood onto side branches of two rows of trees as an experiment. In September, when the grafts had grown up to six feet long, Coates went back to the orchard to bud in Skeena cherries. He put cherry buds into the Adara shoots every eight inches.

Though Coates has been using Adara as an interstem for about five years in California, this is the first time he has tried it in the Pacific Northwest. He doesn’t know yet whether the Adara will be hardy enough, but will find out this winter.

In February, during the dormant season, he will remove the budded Adara shoots, cutting above the bottom cherry bud, which will remain on the tree. He’ll put the rest of the wood into cold storage and will cut them into eight-inch scion pieces, each of which will have a sleeping-eye cherry bud. In April, he’ll carefully graft those into the rest of the trees. The cherry buds will grow during the 2009 season at the same time as the graft is healing in.

One step

Coates said growing the Adara shoots in the orchard as a source of interstem wood has two advantages. Most of it will be thicker caliper than the wood he could obtain from a nursery, and therefore more suitable for budding. It also saves time because the grafting of the interstem and budding to the scion are done in one step.

"It would be like planting a new tree next spring ­without all the expense and labor," Coates said.

He also experimented this year with whip grafts on some trees. This involved whip-grafting together a dormant scion of cherry wood and a dormant piece of Adara, taping it up, and then grafting the combination onto a plum tree. This was done in the spring of 2008, and the cherry shoots grew the same year. Coates said they will likely fruit in 2009.

"It’s real exciting to see a cherry on the plum in one year," Coates said. "Any time you can gain a year in the market, that’s what we want to do."

Harold Schell, director of field Services at Chelan Fruit, Inc., Chelan, Washington, said grafting over the trees gets the grower into cherry production sooner, particularly if nursery trees of the desired rootstock-variety combination are not immediately available.

Coates said the Manson orchard was the perfect scenario for conversion to cherries because the new cherry growth can be trained immediately to the wires."

The new trees will in effect be double interstems, with the Citation rootstock, then Amber Jewel plum, then Adara interstems, and finally the Skeena cherry on top, but Coates knows of no disadvantage to that.

Peaches

The Adara rootstock would work equally well for converting peach or nectarine trees to cherries, although, curiously, it doesn’t work for converting other stone fruits to peaches, he said.

"Potentially, we could graft over a peach orchard to cherry as well, which is real exciting," he said. "This has been a fun project. As long as I’ve been in this business, when I think I’ve done it all, something else comes along, and that’s nice."

Steve Terry, chief executive officer at Chelan Fresh Marketing, said the company handles just two thousand boxes of Amber Jewel plums. One retail chain uses them, and some other chains have shown interest, but competition from California is tough. Fruit at the high-elevation orchard at Manson matures in late August.

"The problem with the Amber Jewel is it runs into the plums from California," Terry said. "And when California has a big crop of soft fruit and plums, it makes it very ­difficult."

The California soft fruit industry has planted many later varieties, some of which go onto the market as late as December, Terry said. "Back in the old days, California used to run out of soft fruit by the Fourth of July, and the apple market used to go up $2 a box on the fifth, just based on that.

"All of a sudden, California just kept planting soft fruit and going into July and August, and now September and October. It’s amazing."

Concerning the market for cherries, Terry said Washington hasn’t had the crop yet to fully test the size of the market. It had a short crop this year.

"We’ve got some big cherry crops coming up in the future," he said. "We’re going to see how many cherries the consumer can consume."