Rodney Klenk explains his production system, with support from Wally Heuser (right), his long-time advisor.

Rodney Klenk explains his production system, with support from Wally Heuser (right), his long-time advisor.

Rodney Klenk credits much of the look of his cherry orchards to his long relationship with Wally Heuser, chief executive officer of International Plant Management and the person largely responsible for the introduction of Gisela rootstocks and many new varieties to eastern U.S. cherry producers.

Klenk, a third-generation grower on Michigan’s Fruit Ridge, continues to try new things, often working on projects in cooperation with Heuser.

Heuser returns the compliment. He calls Klenk a pioneer. Almost 25 years ago, Klenk began abandoning the traditional Mazzard rootstocks in favor of smaller trees on Gisela 5, 6, and 12. Klenk has some of the oldest Gisela trees in the United States, Heuser said.

His orchards are planted in rows 16 feet apart with trees 5 or 6 feet apart. Most trees are trained to central leader, and some are staked to prevent leaning. Trees on Gisela rootstocks on heavy soils, like those of Fruit Ridge, grow fast and crop heavily the first years, but the roots take longer to anchor well, Heuser said. Stakes provide support during the first five years, after which leaning isn’t usually a problem. “Trees don’t blow over or break off,” Heuser said, “but there’s a big sail effect, and trees will lean.”

Klenk is trying some trellis wires for support, an idea his dad wanted to try but which is considered risky in the East, where wire rubs can be entry points for canker. He used metal W clips to tie branches to the wires. Some are trying nylon wires, but it’s not known yet whether this will help, Heuser said. Wooden posts can cause cankers as well, so a post must be away from the trunk and on the west side, so wind pushes trees away from the posts.

Klenk uses copper sprays early in the season to ward off canker, followed by a diligent pruning program to take out infected limbs. “We cut out oozing cankers and disinfect them with bleach,” he said. He uses Dr. Greg Lang’s “big ugly stubs” approach to pruning, so if cankers develop they won’t make it to the leader and severely damage the tree.

He does most of his heavy pruning in August, when it’s hot and dry and canker risk is small. Spraying with copper before and after pruning is a good preventative, adds Michigan State University cherry researcher Lang, who, along with Heuser, ran much of the educational side of the program on this International Fruit Tree Association tour stop last March.

As to varieties, “Rodney has tested them all,” Heuser said. Most of his orchards are Cavalier (Rynbrandt cultivar), a variety Heuser helped introduce years ago, but he continues to look for new, good varieties. Cracking is a major problem in rainy years, and some varieties are more resistant than others. Klenk uses wind machines to blow-dry the trees after rains, but otherwise does little to prevent cracking.

Cherries are rarely self-fertile, so the big variety mix is a plus for pollination as well as diversification of risk. Heuser has been working with Cornell University to commercialize varieties developed by Bob ­Andersen before he retired. Both BlackGold and WhiteGold are self-­fertile, making them self-reliant and good pollinators for other varieties.

Klenk is growing seven numbered Cornell selections and also grows the varieties Regina, Hudson, Sam, Schmidt, Summit, Early Robin, ­Sunset Bing, Benton, and Cavalier.

Klenk’s latest experiment, working with Heuser, consists of test rows of trees planted two feet apart on Gisela 3, a very dwarfing rootstock. Klenk calls them “pole cherries”—a small trunk with limbs pruned short and fruit borne close in near the trunk. That style is also being investigated by Italian researcher Stefano Musacchi and Greg Lang.

Klenk is also looking at high tunnels, which could provide rain protection that would go a long way to solving the cracking problem and provide superior picking conditions for U-pick visitors. He’s closely following Lang’s work in that arena.