New York State apple growers who are planting NY1 last year or this year for the first time are being advised to manage them intensively.

It appears this Cornell-bred cultivar is even weaker growing than its Honeycrisp parent.

“The lack of sufficient leader growth to reach the top of the trellis (10 feet) by the end of the third year is a serious problem that limits yield in future years,” say Cornell horticulturist Dr. Terence Robinson and Lake Ontario fruit program educator Mario Miranda Sazo. They gave their advice to growers in the June 25 issue of Scaffolds, a weekly fruit journal published by the Cornell University Department of Entomology.

“NY1 is turning out to be a difficult tree to achieve sufficient leader growth when grown on M.9 or B.9 rootstocks,” they wrote.

NY1 is very precocious. The ability to set a heavy crop early, combined with its inherent low vigor, can challenge growers to fill the space in three years, they wrote.

“There are several important strategies for maximizing tree growth after planting and during years two and three, including a balanced nutritional program, irrigation, excellent weed control, and overall good orchard management,” they said.

Early on, growers were advised to plant at a spacing of three feet or less on the most vigorous M.9 clones or their equivalent. Robinson is now advising a still more vigorous rootstock, like G.935, for both NY1 and Honeycrisp.

In the first year of growing NY1, growers should keep the leader growing until the end of July through intensive nitrogen and water management. Competing buds should be removed from the leader early or cut back in July to two inches to prevent competition. Flowers should have been removed.

Trees should receive about a quarter pound of calcium nitrate at planting, and should get another application in late June. Water should be applied two to three times a week in small volumes, and applying the nitrogen in the water is recommended.

“It is also imperative to maintain excellent insect control and excellent weed control at least through the end of July,” they said. “This should result in 18 inches of leader growth by the end of the year.”

For growers who planted NY1 last year, the horticulturists recommend they be defruited this year so the energy is directed to growth. Despite the freezes this year, the cultivar seems to have set a crop, they said.

“In years three through five, we suggest a strict crop load management program of four fruits per square centimeter of trunk cross sectional area to balance growth and cropping,” they said.