Pruning the Orchard: Part Three of a Three Part Series

3/19/2019 - 9:54:36 AM

 

Last week, we learned what a pruned tree should look like. There were even pictures! This week we want to delve into some other benefits that pruning brings to the tree. Disease and pests are a constant reality that must be managed with diligence and wisdom. As much as possible, we implement the most natural solutions to these threats. Here’s Clair...


In the past, we’ve talked a lot about Integrated Pest Management and all the different types of controls we have to deal with pests and diseases. Well, we have a set of things called Cultural Controls which have nothing to do with directly killing pests or curtailing disease. These controls don’t have anything directly to do with pesticides, but they are often considered fundamental to preventing bigger issues down the road. Pruning fits squarely within these set of controls. Improperly pruning a tree will significantly reduce sunlight penetration, along with air flow through the tree canopy and the orchard. Not only is sugar production compromised when sunlight doesn’t penetrate the tree, its canopy will hold moisture longer than it should. Air flow and sunlight penetration enables the canopy to dry out sooner. Dense foliage, which prohibits wind and sunlight penetration, will also trap moisture from an overnight rain or heavy dew. And then if you have a hot day, all of these factors combine to create a hotbed for disease and a welcome haven for some insects. They love the densest, thickest part of the tree for the obvious protection it provides. On the back end, when we do spray for insects or diseases, we’ll have a hard time getting spray penetration through the entire canopy if it’s too thick. In relation to this aspect of Culture Controls, our best blocks consist of rows of trees pruned to a two-dimensional fruiting wall and not so much three-dimensional trees. A two-dimensional tree is easily penetrated by sunlight and air. And so, our newer plantings have a bit more of that architecture.

 

 

As mentioned earlier, moisture is a prime environment in which to rapidly grow a lot of fungal and bacterial diseases. Certain temperature and moisture levels will trigger our radar. It starts blinking and we say, “Oh my!”  A weekend rain event will often result in a bacterial leaf spot infection in our stone fruit. Or we might have a fire blight infection in the apples (a bacterium) in the spring right after bloom. Or later in the season, we might see apple scab or bitter rot, both of which are types of fungi. Each of these diseases thrive in moisture. Sunlight and airflow are critical. So, if we do a good job pruning in the winter time, we've probably done half the work. That’s a broad guess, but we’ve certainly accomplished a good deal of the work of preventing disease and reducing pest pressure.

 

 

Speaking of pest pressure, pear psylla is a good example. Not quite microscopic, this particular insect hangs out in our pear trees. You can see it with the naked eye, but it’s especially easy to see with a magnifying glass. It’s the primary pest of our pears. They love to breed and live in the center of a tree, in fast-growing shoots where there’s lots of foliage. And so, it’s very critical that we open up our pear trees for lots of airflow and sunlight an excellent prevention for pear psylla. We will even go through in the early summer and tear out by hand, what we call suckers that are starting to grow around the middle of the tree. These are fast-growing, upright suckers or water shoots, branches in just their first season of growth. They grow very fast and upright, which is very typical in pears. Since they’re not reproductive, and they're branches we would prune out in the winter anyway, we’ll get them in the summer when they’re easy to tear out. Another a cultural control, this practice goes a long way in reducing the habitat for pear psylla.

 

 

Another significant factor in pruning the trees, is the front end of crop load management. Crop load management is a very significant part of an orchard manager’s tasks throughout the year. So, to get the ideal crop load it is critical for us to get optimal yield, but also, we don't want too much, because if we have too much fruit then we'll have poor sizing and poor flavor. So, that sweet spot is really hard to achieve. Often at the beginning of the spring, we actually have too much fruit, which is especially the case with apples. We virtually almost always have too much of a crop load of most of our apple varieties. Pruning addresses this overabundance, as we are taking buds and fruiting potential out of that tree. Keeping those branches would lead to many more apples on that tree that would only end up being thinned come springtime. And sometimes that means taking them off by hand when we've exhausted other means of control. That's very costly and very time-consuming. Crop load management is important, so, especially in young trees, we're very careful to manage the crop well by pruning. Additionally, with varieties that crop very heavily, we might prune them a little harder.

 

 

Peaches are a good example here. You can virtually go around a tree and count how many fruiting sticks or fruiting whips you want and prune down to that number. You’ll have a significant amount of your crop thinning done for the year just by pruning appropriately and pruning out all the branches that would produce slightly less desirable fruit and leaving only branches having the highest likelihood of producing high-quality fruit. Crop load management is also crop quality management. Bud size, branch shape, length, and placement will all indicate what quality of fruit you’ll have. Especially in a peach tree, it’s important to understand the physiology of fruit trees, where the quality fruit wants to grow, what types of branches grow that quality fruit and then pruning accordingly. In this way we get closer to the optimum balance of crop size and quality.

 

 

Hey, thanks for reading about the work we do in our orchard. It’s not easy, but it’s worth it. As mentioned in part 1, working with our hands, and being outside is so rewarding and uplifting. We leave you with just a taste of this life. This footage is from last fall. Daniel Kauffman captured these moments with his drone mounted camera. Enjoy!

 

 


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