Apr 30, 2010

Terence Robinson: The Future for Orchards is Tall Spindle

Terence Robinson, an applied fruit crop physiologist with Cornell University, wants to help growers find the most cost-effective way to run their orchards. His recommendation: a high-density, tall spindle system.

“A low-density orchard will never catch up to a high-density orchard system,” he said, “even though density production eventually levels out to some extent.”

Robinson doesn’t hesitate when he recommends the tall spindle system.

“If you plant 900 to 1,300 trees per acre with 3 to 4 foot spacing between trees, and you manage those trees, you will maximize profitability for your orchard,” he said.

Just what is a tall spindle system? Briefly, Robinson said, the grower plants 9- to 12-feet-tall, highly branched (feathered) trees with 3- to 4-foot spacing between them. There should be 10 to 13 feet between rows. Branches are trained to bend below horizontal for ease of management. There will be no permanent scaffold branches that attach at the trunk, but rather small fruiting branches that are pruned when they reach two-thirds of the diameter of the trunk. The trees may require minimal pruning at planting.

The difficulties are reduced due to natural competition between trees.

“If you’re worried about having to do excessive pruning, you needn’t worry,” Robinson said. “Tree size will decrease naturally with higher tree density.”

From Robinson’s experiments, the more successful tall spindle orchards established to date have been on M.9 and B.9 rootstocks. Robinson said precocious dwarfing stocks are important, since early cropping is essential. Geneva 41, G.11 and G.16 are also appropriate rootstocks where fireblight is a concern.

Another key, Robinson said, is to reduce vigor in upright scaffold branches. Bending the branch below the horizontal axis does this. Branch weights, rubber bands or tying can all be successful, although Robinson points out the importance of using a UV-protected rubber band to keep it from deteriorating due to sun damage. Branch bending maintains a proper amount of vigor, keeps trees within allotted space and encourages the production of fruit buds for the following growing season, he said.

The bottom line is profitability.

“This is the only system we have ever tested that achieved a cumulative production over 1,000 bushels in the first five years,” Robinson said. “This resulted in approximately a 40 percent increase in crop value compared to the slender vertical axis and sol axis planting systems.”

The second year’s crop is very important, Robinson said, to help ensure the profitability of the tall spindle planting system. The apple crop can approach 100-150 bushels per acre on precocious tree varieties, giving growers an immediate return on the investment.

A common question revolves around whether or not a grower can afford to switch to tall spindle. Robinson’s research has proven that it is a good investment for a long-term plan. Getting high-quality trees is a must, he said, to attain maximum profitability. He also advised planning well in advance. Going to the nursery and ordering the trees a year and a half in advance can quite often save 20 percent to 25 percent.

“With this system done right and with good quality trees, it is very probable that four to five years in, you’ve already paid back the investment,” Robinson said. “It allows a grower to move on to the next block that much sooner. The high-density system has been the most productive, with the highest and earliest production. Production began with a small crop in the second year and very high yields by the fifth year. In 2009 (year eight of one research trial), the tall spindle system produced yields of 1,200 to 1,600 bushels per acre.

“This research demonstrated much higher yields than we previously thought possible, with the tall spindle system at a relatively young orchard age,” Robinson said. “This high-yielding system, when coupled with a high-priced variety like Honeycrisp, can dramatically change the orchard profitability potential for new orchards. We’ve never been able to achieve as high of a yield with Honeycrisp as we do with some other varieties, but the profit margin makes it work.”

If you’re wondering if you can grow apples in a high-density system, Robinson has some insight. Experienced growers need to understand that this is quite different from other growing systems, he said. It takes time and an understanding that there is never a large branch, which was common on older systems. His advice is to plant a small section in high density and go from there. Growers who have never worked with apples before tend to do best right out of the gate with tall spindle. They have an easier time grasping the concepts and freely take advice and seek help, Robinson said.

The best advice Robinson can offer is to jump in.

“It’s a learning process, but it isn’t that difficult,” he said. “Learn from your mistakes and work with your Extension people; they are a great resource.”

He also advised communicating with the International Fruit Tree Association and talking to other growers.