Cold Weather Pruning Considerations
2020 has certainly presented its share of challenges! Lack of available toilet paper aside, we had cold snaps in April and October that clobbered us. Unfortunately, a lot of damage was incurred due to lack of cold weather acclimation in tree fruit and grapevines at both timings. With this in mind, it would be prudent to examine your pruning strategy before you put your loppers to work. This fall/ spring, take into account possible bud loss and overall tree damage. Take a walk through your different block varieties, cut several buds and scrape some branch tissue to get an idea of the damage that you might not otherwise know was there. Examine samples from different levels in the tree, up high, in the middle and down low. If you’re noticing a lot of dead buds or damaged branch tissue, it would be a good idea to prune less aggressively in those blocks. There is an opportunity to do additional blossom thinning next spring if there’s too much left on the tree, but you can’t put back what’s already been pruned off!
Here’s a link from CSU showing what to look for when cutting buds and scraping bark;
That said, let’s visit the rules of pruning for our new growers in the neighborhood.
· Start pruning the tree from the top downward, outside inward. This removes the chances of a top heavy tree. It forces you to balance the tree and eliminates the chance of leaving too many branches (structure wood) in the top because you pruned too much off the bottom of the tree.
· Remove laterals (big branches) with diameters that exceed 50% of the branch they originate from. Look for the “big” branch and cut it out. Look at the tree from a distance before you start to determine which “big” branches need to be removed. This rule applies both to branches originating from the central leader and side branches off of scaffold limbs. This process removes dominating laterals, distributing vigor throughout the tree. A tree with “distributed vigor” will naturally grow more fruiting wood. On pome fruits use “stub” cuts which will produce soft re-growth and fruit buds.
· Stub off vigorous uprights to redirect energy and light through the tree. With stone fruit it’s critical to remove these from inside the interior of the tree. On pome fruits a stub cut “upright” will often produce weaker horizontal fruiting structures.
· Remove weak, pendant fruiting structures. This rule will help keep the “fruiting wood” in your tree young. Removing weak branches increases light penetration and thins off weaker spurs which saves on chemical or hand thinning later. Weak spurs or fruiting buds often bloom at a different timing, and persist with poor quality crop until removed. Dormant pruning will invigorate the area and direct energy into production of higher quality buds that are better able to withstand spring frost.
· Do not allow too many branches in the tree, even if they are below the 50% rule. Excess branches “tax” the system and reduce light penetration. Experience will tell you where the balance is that allows for production of maximum fruit numbers and size.
· Prune towards a goal. Have an idea of how many boxes of fruit you want to harvest off of each acre. Work that number backwards to determine how many fruit per tree you need, then prune towards that number. Prune a few trees and count the fruiting sites left. Following this rule will reduce your thinning bill and increase your fruit size. Put a note on your calendar to count fruit per tree just prior to harvest. This timing allows you to judge crop load and fruit size. TAKE NOTES! When pruning and thinning time comes around the following year you will be able to take most of the guessing out of your work.
All of us who farm have one of our most critical “inputs” delivered to us daily at no cost! SUNLIGHT. Sunlight is what drives the system. It’s what gives your fruit taste, size and color! Following these rules will help you take full advantage of one of your greatest resources, the sun.
If you have questions about these rules, let us know and we’ll explain them further. We would be happy to demonstrate them on your place. It’s a good time of year to plan for the coming season, if you would like to discuss herbicides, fertilization, or pest programs give us a call and we’ll stop by.
Here are a few key factors affecting the production/profitability of a block of fruit:
· Tree spacing, rootstock, and variety – Maximizing the amount of sunlight captured by each acre should be part of your production goal. The right rootstock/variety combination planted at a spacing that will fill the orchard acre is vital to your success. Too much blue sky between the tractor and tree row cuts down on your harvest.
· Weather – While there are certainly some sites better than others when it comes to spring frosts, I don’t know of any completely frost free sites on the West Slope. Is fighting frost part of your production goal? Do you own a wind machine? Is it ready to run for one of our minus zero winter nights?
· Soil - How deep is your soil? A lot of us farm on shallow, calcareous soils. Twelve to eighteen inches of topsoil is all we have to work with. I’ve observed a number of fifty plus year old trees pushed over that had root systems only two feet deep. It’s an accurate analogy to say we farm trees in pots. This fact should be considered in our decisions regarding nutrition and irrigation.
· Pest and Disease – Does your production goal have a pest/disease threshold? Are you willing to accept some level of damage? Do you understand the impact a pest population this year can have on next season’s crop?
“The farmer has to be an optimist or he wouldn’t still be a farmer.” — Will Rogers