Pruning highbush blueberries

UNH Extension Fruit & Vegetable Production Field Specialist Heather Bryant started her half-hour class on pruning blueberry bushes by introducing the tools she uses.

Long-handled bypass loppers provide the leverage needed to cut and remove no-longer vigorous blueberry canes, Bryant explained. Commercial blueberry growers with many bushes ordinarily sharpen their blades every day. Bryant keeps a small folding file in her pocket with which she sharpens blades, using long smooth strokes.

Smaller hand pruners, outfitted with a locking safety feature, are also typically used. Commercial growers are apt to carry a folding saw that looks somewhat like a giant locking jack knife that’s useful when cutting larger diameter canes, Bryant explained.

Highbush blueberry bushes are pruned when they are dormant. The only exception, she emphasized, is that a nasty scraggly fungal disease called “witches’ broom” should be removed whenever it’s spotted. Caused by Pucciniastrum goeppertianum, which results in clusters of stunted, swollen and reddish-brown shoots, it requires both blueberry plants and fir trees to complete its lifecycle.

“Blueberry bushes should never be planted within 500 yards of Balsam fir,” Bryant warned.

Any cutting edge that contacts this rust fungus should be sanitized each time.

The first year after planting a blueberry bush, any broken branches should be removed, plus all the round flower buds, Bryant recommended. Emerging leaves are flat and look quite different from budding fruit.

“The idea is to send support to the root system and not to any fruit,” she said. “Ideally, this is also done in the second year.”

Bryant strongly recommended getting a soil test done before any bushes are planted.

“Blueberries thrive in acidic soil, a pH range of 4.5 or 4.6,” she said. “I like having scientific data before I add anything to the soil.”

Highbush blueberries are usually planted at least five feet apart in rows that are eight to 10 feet apart, allowing a mower to keep the corridor trim. Set healthy two- or three-year-old plants in early spring. Dig a planting hole at least twice as large as the blueberry plant’s root system.

Blueberries require little pruning during the first two or three years, other than removing dead and/or weak branches. It’s after the third year that annual pruning should be scheduled, but only while the blueberry bushes are still dormant.

Bryant believes that 85% to 90% of blueberry growers don’t cut hard enough. “Remember,” she pointed out, “the perennial part of the bush grows underground.”

This pruning demonstration was in a commercial blueberry plantation in Windy Ridge Orchard, located in the county seat of Grafton County, NH, where a mix of medium hardy or hardy bushes, such as ‘Jersey’ or ‘Patriot,’ are typical. Growing more than one variety helps ensure cross-pollination takes place.

Windy Ridge Orchard has installed irrigation lines in its blueberry plantation, and Bryant took care not to cut into them.

The task at hand, she explained, was to remove all no-longer vibrant canes, leaving from six to 12 mature canes. Those over six years old often support pale green lichen.

Any weak or scrawny shoots should also be removed from the base, leaving an airy, open bush in which breezes and sun streams in. “Only a few nice, straight, young canes should be retained,” Bryant noted. These healthful open conditions reduce the likelihood of invasive fruit flies laying eggs on not-yet-ripe berries.

Bryant said a good rule of thumb in the Granite State is not to fertilize blueberries after the Fourth of July. Holding to this rule prevents tender growth from developing late in the season, leaving it vulnerable to freezing conditions.

UNH Extension has fact sheets available online on all aspects of growing highbush blueberries. It also highly recommends an outstanding online video, “Pruning Blueberries,” that features University of Maine Cooperative Extension Fruit & Vegetable Specialist Dr. David Hanley pruning mature bushes. (Find it at tinyurl.com/PruningBlueberries.)

The pruning demonstration took place on a farm that has grown and changed over the years. The Fabrizio family moved to Windy Ridge in summer 1967, according to their website. The farm had been owned by Russell Dexter’s family and had operated as a dairy farm for more than 80 years.

Mom and Dad pondered a few options for the land, including a dairy and/or campground, but settled on the idea of apples. The first trees were planted in 1968 behind the house, and the Sugarloaf Block was planted in 1971. Within a couple of years, the five Fabrizio kids began selling apples on the front lawn. As the orchard grew, operations were moved into the garage.

With the help of Grandpa Fabrizio, a cider room and sales room were built in the garage and apples stored in the carport. Sales were conducted on an honor system, and the first school group came for a tour in the early ‘80s. Dad worked full-time as the Grafton County 4-H agent; Mom was a full-time teacher; and the kids kept an active 4-H dairy and sheep farm. Harvest time was always very busy.

The Black Mountain Block was planted in 1980, and the current apple building with cold storage was built in 1983. Most of the apples and fresh pressed apple cider were sold to area supermarkets. Dad continued to gain a stellar reputation for great quality fruit, and Mom kept busy working the store after school and on weekends.

In the mid-1990s the latest planting took place in the 7 Oaks Block. These trees of new (Honeycrisp) and old (Mac and Cortland) varieties were planted on a trellis system for increased productivity and ease of picking. In 1995, Dad retired from Extension; Mom retired in 1998; and Sheila returned from the Peace Corps.

Since then, they’ve made a concerted effort to create a family destination for local friends and visitors. The farm animals, playground and nature trails were all started at this time. Windy Ridge’s consistent mission is to provide top quality fruit and a friendly farm experience for the whole family.

by Edith Tucker