There is a belief among people that there’s not much to do around the farm during winter. While it is a slower time for us, there is still plenty to do. The bulk of winter activity revolves around catching up on book work, Steve attending meetings and of course, pruning.
The primary goal of pruning is to manage sunlight on the tree. Trees are solar collectors and pruning helps manage where the sun is collected, which in turn dictates the crop load (in addition to water and weather). We have about 35,000 trees, and every single one of them must be pruned. Every tree, every year. This is a job that takes 5 months to complete for a crew of three to four people. Our guys start pruning in late November, after irrigation lines have been put to rest and the farm cleaned up. They prune five days a week, eight hours a day. It is not a job for the weary as the majority of the work is atop a ladder, holding pruning shears above one’s head in cold weather. It’s fun to do for about four hours. After that, it becomes hard work.
We start with pruning pears, then work through apples, cherries, plums, and finally peaches. Why this order? There are several reasons, the first of which is the potential for winter damage. All our trees naturally go dormant and develop hardiness as fall and winter progress. Pears and apples are very hardy, meaning that they go into dormancy quickly and can survive very low winter temperatures. Ever stop to think why pears and apples are grown in the upper Midwest, but not peaches? That is the reason – peaches die in those super cold temperatures they have. When we prune trees, we wake them up a bit. They lose some of that hardiness and are more susceptible to cold temperatures for a while. Pears and apples are so tough, that even though they “wake up” a bit, they are still very resistant to cold. Peaches, not so much. So, we let them sleep until the warmer temperatures of spring.
Secondly, depending on the time of year you prune a tree, you get a different growth response. A cut made on an apple or pear in winter will cause a vigorous response – regrowth of new, succulent limbs. That same cut made after they start to green up, will cause a much calmer response. That cut made in the summer may cause no response. Just like teenagers, trees operate on hormones and those cuts cause different hormone responses at different times. Generally, we want a vigorous response, so we prune apple and pear trees in the winter. But, if we have trees that are too vigorous, we will wait. Peaches don’t show this same marked response difference, so we can wait and prune them later, when we can see those swelling buds. Then we can use our pruning to adjust the potential crop on the trees.
For all the science, pruning is still an art form. You would think that after thousands of years of pruning trees, that people would finally have it down. But, ask any grower about how they prune and you will likely get a different answer from each person. All trees are not alike and each variety behaves differently as well. Throw in the fact that all growers have their own little quirks, and, art emerges over science. Besides, every grower needs some coffee time with other growers to talk about something – they might as well argue and debate over pruning rather than politics. But, pruning is safer and unlike politics, you have something to show for it at the end of the day!