Multi-leader Apple Tree System Impresses International Growers

By Matthew J. McCallum

You know you’re onto something when a group of apple growers from around the world stops in their tracks and marvels at your orchard. That was the reaction Italian orchard manager Michele Gerin received when he hosted the International Fruit Tree Association Study Tour in November, showcasing his multi-leader apple tree system.

Gerin is a farm manager for the Mazzoni Group, which grows more than 5,000 acres of fruits and vegetables in northern Italy’s province of Ferrara. The fully integrated operation produces both conventional and organic crops, markets them fresh, and also processes produce into frozen products.

The Mazzoni Group’s goal is to improve fruit quality, reduce labor, and increase yields in its apple blocks. Since 2017, the operation has exclusively planted apples using a multi-leader apple tree system, abandoning the slender spindle approach. Today, the farm grows 500 acres of apples, half of them Pink Lady.

The multi-leader system produces a wall of fruit with a thin canopy that allows better light penetration for improved fruit color.

Growing Apples with the Multi-Leader System

“The goal is for each tree to get more light for more color because we don’t have enough cool temperatures here,” Gerin said. “We want a thin canopy.”

The system uses a 15% shade cloth that doubles as hail protection. Trees are trained on a six-wire trellis with drip tape attached to the first wire. Cement posts replace wooden supports to ensure long-term durability.

Gerin uses M.9 rootstock, which balances vigor with the soil and fertility of the area. Spacing between rows ranges from nine to eleven feet, with four feet between trees. He chose stronger rootstock compared to slender spindle because densely planted rows had reduced vigor.

Color remains a challenge due to warm weather and limited cool nights. With Pink Lady, the multi-leader system colors fruit about eight days later than slender spindle.

“We think it is because the engine of the tree is smaller and it takes more time to give color to the fruit,” Gerin explained.

Managing Canopy, Labor and Fruit Quality

To improve coloring, the farm uses a defoliator machine to blow leaves off trees about 20 days before harvest, or in early October. Defoliating too early reduces color, Gerin noted.

The Mazzoni Group also grows its own nursery stock of two-leader trees, costing about $15 each, roughly twice the cost of single-leader trees. While the system is more expensive initially, Gerin believes it pays for itself over time.

Photo: Shade cloth is required on all Mazzoni Group apple plantings due to the high heat. It also serves as hail protection.

“In the first three years we have 700 more labor hours per hectare training and affixing all the leaders to the wire compared to the spindle,” he said. “But once done, pruning and harvesting are much simpler and cost less than the slender spindle.”

Mechanical pruning in June further reduces labor. The system produces about 90% premium fruit compared with 65% under the slender spindle system.

“We are also looking to reduce volumes and rates of our spray because there is no inside of the canopy to reach. We believe we may be able to use it without a blower.”

A System Built for the Future

After five years, Gerin is confident in the results. While the multi-leader system requires considerably more training in the early years, he believes the long-term advantages in labor savings, fruit quality and orchard efficiency make the investment worthwhile.

“This system is very expensive on the front end, but pays off handsomely in later years,” Gerin said.

With international growers impressed and results to prove it, the Mazzoni Group believes it has found a winning system for the future.

Originally published in Fruit Growers News, January 2023.