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Some Lessons from the 2007 Growing Season

One of the things that continues to challenge estimators during the growing season is the potential size of any crop. Sayings like “a small crop gets smaller and a big crop gets bigger” can carry some truth. What is truly amazing this year was how we managed to produce the volume of fruit in Ontario that has been reported through the harvest season after seemingly over thinning some blocks and in one of the hottest and most rainfall deficient growing seasons ever.

Crop volume of course is directly related to fruit numbers and average fruit size. This year, I believe we had the fruit numbers right from the start; it was the challenge of fruit sizing was at question during the 2007 growing season. Surprisingly, some growers did report the largest crop they had ever grown. Other growers reported very large volumes of smaller sized fruit, which is understandable when considering the 2007 growing season.

We had a couple of things going on in the early part of the season that helped get us off to a good start in many areas. Soil moisture reserves in the spring were there. We had one of the better bloom/fruit set periods that we have seen in a number of years. This was in spite of the fact that many growers had the perception of thinning programs where they had sprayed too much fruit off the trees in late May and early June.

I have always maintained that if you can easily find the apple fruitlets with a casual stroll between tree rows in the middle of June, there is a good chance you have not taken enough of the crop load out of the canopy to achieve the right leaf to fruit ratios. It is common that trees that typically look overthinned in the early part of the growing season can produce a nicely balanced and well sized crop at harvest.

Some blocks in 2007 never received rain when growers needed it and producers everywhere had difficulty keeping up with evapotranspiration losses even though they pumped water at capacity for most of the growing season. It was a good year to test the theory about how to size fruit load under extreme heat, UV, and soil moisture deficits.

An interesting observation that was made by more than one grower this year was that trees well pruned to smaller diameter wood produced larger fruit when compared to trees poorly pruned or not pruned at all during the previous dormant season in the same block. This really drives home the point of good pruning practices (Figure 1) and their influence on fruit quality. This is one area of crop culture that a grower should look at carefully before cutting corners. If trees that were well pruned had any lack of nitrogen supply, canopy thinning would have been extremely helpful. The root system would in theory pick up as much nitrogen and distribute it to the crop without starving any part of the canopy.

And yes, a thorough and heavy pruning program can mean cutting back substantially on nitrogen as an input but care should be exercised so as not to starve the tree in the process. Under fertilizing can cost yields and quality while over fertilizing has both environmental and financial implications. Soil testing on a regular basis should be combined with tissue testing and comparing results to known standards.

Figure 1. Trees in higher density plantings with excessively strong or large caliper limbs arising from the main trunk have to be removed otherwise they will prevent the production of preferable smaller diameter branches on the same side of the tree.