Growing large Galas, especially in the eastern United States, is challenging, though it can be done by combining aggressive pruning, thinning, high fertilization, and irrigation. But does it pay to produce large sizes?
Galas, now a staple variety throughout the country, can command a significant premium for large fruit in the 80- to 88-count sizes, said Dr. Terence Robinson, horticulturist at Cornell University’s Geneva, New York, research station. "But the problem on the East Coast, and elsewhere, is that we grow a lot of small ones."
He explained that the popular variety is predisposed towards small sizes—it is genetically small fruited, produces profuse flowers on one-year wood, sets heavy crops, and is not biennial, which leads to repeated heavy crops that decrease tree vigor over time. "Trees that are low in vigor are difficult to thin, which further compounds the problem," Robinson said.
He started a research project to grow larger Galas five years ago, studying the effects of pruning, thinning, fertilization, and irrigation. "I think we’ve figured out how to grow larger Galas. But does this maximize crop value?"
In years when smaller fruit are abundant, there can be a significant price spread between Galas. During the 2005-2006 season, Washington 80-count Extra Fancy Galas from controlled atmosphere storage sold for an average f.o.b. of $21.41 per box (42-pound equivalent), reported the Washington Growers Clearing House Association. The same grade of Gala in 100-count boxes sold for an average f.o.b. of $16.01. Regular storage Extra Fancy 80-count Galas sold for $21.77; 100-count of the same grade were $14.39. Galas sized at 125 sold for $12.34, with 138s and smaller selling for less than $11.50.
"There’s really no market for 120s, or 140s," Robinson noted. "You can get larger fruit size by reducing crop load; however, when you reduce crop load, you reduce yield."
Robinson believes there is an optimum balance somewhere in the middle where sizes are increased but yields are not reduced below what is profitable.
From 2003 to 2005, field studies were conducted at the Geneva experiment station in New York on six- to nine-year-old Gala trees planted on M.9 rootstock. Management factors known to influence fruit size were compared individually and combined to determine the most effective ways to increase size.
The split trial included three pruning treatments of limb renewal, spur extinction, and stubbing back; two chemical thinning treatments of BA (benzyladenine) plus carbaryl and NAA (napthaleneacetic acid) plus carbaryl; three rates of nitrogen (normal, double, and triple amounts); and drip or trickle irrigation compared to no irrigation.
Of the four management factors studied, pruning had the greatest effect on yield and fruit size, he reported at the Great Lakes Fruit, Vegetable and Farm Market Expo in Michigan.
Spur pruning and stubbing back both reduced blossom density by one-third compared to limb renewal pruning. Crop load was reduced by 20 percent in the spur pruning treatment and 25 percent in the stubbing back compared to limb renewal.
"Spur pruning—aggressive pruning—brought us to about the crop load levels we wanted without doing any hand thinning," Robinson said. "By dropping some buds on the ground with the pruning shears, we achieved the bud load and crop load we wanted."
Of the thinning treatments, in most cases, BA and carbaryl gave the best improvement in fruit size, although the thinning treatments overall had an intermediate effect on fruit size. Multiple sprays, such as 2% ATS (ammonium thiosulfate) at full bloom, 600 parts per million of carbaryl at petal fall, and BA/carbaryl at 10-millimeter fruit size, gave the best results, with fruit averaging 185 to 195 grams.
He noted that high rates of fertilizer improved yield, but not fruit size. Irrigation had little effect on yield or fruit size except in 2005, a dry year, when there was an irrigation effect. Fruit size that year was significantly larger than the treatments without drip irrigation; however, even with irrigation, size was still smaller that year than the other years.
Robinson concluded that it is possible to consistently grow large Galas in New York. "But it takes multiple applications of thinners and pruning. When you combine aggressive pruning, high fertilization, multiple thinning sprays plus irrigation, we averaged fruit sizes of 194 grams in 2003, 184 grams in 2004, and 157 grams in 2005.
"You can produce large Galas, but is that really what we want to do? To get 190-gram-sized fruit, we had to knock yields back, and it took tremendous expense to do so."
Robinson calculated theoretical curves to predict the optimum yield and fruit size for Gala that would maximize crop value. He did this by relating crop load and fruit size for each year, constructing a theoretical yield, packout, and crop value curve for the range of fruit sizes. The theoretical curves were then used to predict optimum yield and fruit size for each year.
Optimum yield varied widely between the years as did optimum fruit size. In 2003, yields were from 750 to 900 bushels per acre, but in 2004, a year with a heavy crop and large fruit size, yields ranged from 1,600 to 2,000 bushels per acre.
The curves predicted that when yield was reduced, crop value increased to an optimum crop value, but further reductions in yield beyond the optimum resulted in reduced crop value. The bottom line is that while fruit size is important to returns, yield is much more so.
While the market clearly rewards larger-sized Gala apples, Robinson said that the greatest returns to the grower came from high yields of Galas of moderate fruit size (100 to 113 count, around 160 to 170 grams).
He said the data suggests that eastern U.S. growers should target the 100 to 113 sizes for optimum crop value. "It means that we’ll get a lot of 100s, some 113s, and a few 80s. But to get 80-count Gala apples, it costs too much in New York in terms of yield."