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Keeping Gala Trees Productive

In the minds of many apple growers, Gala is a relatively new player in the variety mix here in Ontario. However, we’ve watched Gala plantings in Southern Ontario for the better part of a couple of decades now. A lot of those blocks planted in the last few years are looking very mature. In fact, many of these Gala trees have lost their ability to produce adequate fruit size for today’s market place. Fruit size distribution in the tree canopy can decline rapidly if maturing trees don’t get the best management options.

For some of these trees, their best days could be behind them if they are loosing vigour and becoming too spurry with little renewal growth in the canopy. A tree with these particular traits will produce an average fruit size that will diminish quite rapidly and with it, tonnage that won’t return the dollars it should because fruit is just too small (Figure 1). Crop value can change rapidly with a pronounced reduction in fruit size on older spurs. Can anything be done? The answer is unequivocally yes.

Unfortunately, both aggressive thinning treatments and application of extra nitrogen won’t necessarily solve the problem. One of the more outstanding treatments resulting in a good tree response is reducing the numbers of fruiting spurs per centimeter of cross sectional area. This is a good topic of discussion in the field at a pruning demonstration or in the classroom. Dr Terrence Robinson of New York State has spoken on this topic many times, as all Gala growers in the Great Lakes area are looking at the same phenomenon regardless of the locality.

A number of years ago I witnessed some seemingly brutal tree treatment when an experienced grower raked off most of the spurs off the lower side of a branch with one swift brushing by hand. Other growers will actually carry out the same treatment with a swift brushing move using the end of the pruning lopper. Both of these treatments actually help dramatically and will remove hundreds of excess spurs very quickly. Small diameter Gala wood is generally considered to be more brittle and is easily broken or snapped in two.

Figure1. Tree tops showing an excessively spurry condition in a mature Gala tree.

Trying to solve the fruit size problem with growth regulators like Promalin won’t work when temperatures are cool around the bloom/fruit set period and extra nitrogen could easily result in a higher degree of disease expression like fireblight. While thinning treatments will definitely help in the short term, the long term and sustainable solution has to go back to canopy renewal and spur extinction methods. Other treatments that could help with fruit size include the use of irrigation and particle film technology.

Canopy renewal in mature Gala can consist of the elimination of larger diameter “tree-like” offending branches (50% rule). There is always one or two of these branches. Cutting at a bit of an angle (Dutch cut) may help generate a bud break and a new shoot to fill in the canopy. It’s these 2-3 year old branches that have the ability to produce the largest fruit.

Spur extinction by breaking off or cutting off every 2^nd or 3^rd spur will reduce the crop load and increase average fruit size. Stubbing back and removing a high percentage of 1-year-old wood will also reduce the energy and carbon getting into an unnecessarily large number of spur clusters (Figure 2). 

Figure 2. Mike Versteegh demonstrate canopy renewal techniques on Gala at a recent pruning Workshop organized by apple growers in the Georgian Bay area.