It was interesting to note how often the topic of “big branches” came up on the Hort show tour this year. Pruning was discussed at each stop. Branches too large for their position in the top of the tree were always the first thing pointed out. New concept? Not hardly! Once again here's the pruning rules given to me by Ivor Marshall from British Columbia back in 1996! These “rules” were originally developed for pruning apples, BUT… if you’re growing fruit on a tree these rules will apply. As you read these rules think about the concepts that they were developed from: The most productive blocks are ones that have a minimum of structure wood and a maximum of young fruiting wood. They are also the ones that have a maximum amount of sunlight from the top to the bottom of the tree. To achieve both of these goals you have to continually remove excess structure wood and cycle in new fruiting wood.
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 fruits it’s critical to remove these from inside the interior of the tree. On pome fruits a stub cut 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.
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 you 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 me know and I’ll explain them further. I’d 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 me a call and I’ll stop by.
It's common knowledge that 4 out of 3 people have trouble with fractions!
Interesting Fact: Talking with Dr. Betsy Beers (WSU) she told me that Wooly apple aphid can travel six feet up a tree trunk in 30 minutes! Wooly's are becoming more of a pest in Washington. Dr Beer's is doing research on their life cycle and movement.
A few new materials in the registration pipeline:
Altacor 35wg (Rynaxypyr) a new product from DuPont. This looks to be a great new material effective against Codling moth (CM) , Peach twig borer(PTB) , Oriental fruit moth (OFM) & Leafrollers to name a few. Has both contact and ingestion activity. Registration expected mid 2008. Long residual (tests against CM show to be as good as Guthion when used twice per generation). Kills by disabling muscle contraction. Feeding cessation (insect damage) occurs rapidly (5 – 10 minutes). No effect on mites. Low bee toxicity. Translaminar activity (moves through the leaf).
Delegate 25WG (Spinetoram) a new product from Dow AgroSciences. Registration expected 2007. This is a chemically altered Spinosad (SpinTor on steroids). Effective against CM, PTB, OFM, Psylla, & Thrips. 14 day residual (3 applications per generation for CM). This material will probably end up replacing SpinTor.
Movento (Spirotetramat) a new product from Bayer Crop Science. Registration expected 2008 or 9.
Effective against sucking pests: Aphids, Scale, Mealybug, White apple leafhopper, Psylla. 21 day residual.
Phloem mobile (highly systemic). This material could have a great fit for Wooly Apple aphid or as a rotation for AgriMek used for psylla.
Info on fireblight from Dr. David Rosenberger, NY. For control or reducing fire blight infections, he indicated that pruning out old cankers is recommended, but that maybe only 15 percent have bacteria. Tools do not require disinfection treatment during the dormant period. Sprays of fixed coppers at green tip might help with control, and that bloom sprays of antibiotics are the most critical part of control. After that, only pruning out of new infections will do any good, and then only while the procedure is feasible labor-wise. If the weather is warm and dry, the cut shoots can be left in the row middles. Apogee does not control fire blight, it only reduces the infection potential of shoots.
Here's a few points from Walt Bentley's talk on thrips at the Hort show:
It's Western Flower thrips that causes the damage on stone fruits.
Thrips overwinter as prepupa or pupa on other plant hosts (alfalfa, mustard, rabbit brush, cheat grass, kochia, to name but a few).
Damage occurs at end of bloom when husk tightens against fruitlet.
Prolonged husk period (wet & cool) increases damage potential.
1st & 2nd instars (not the adults) do the damage.
Minimize tractor travel during bloom.
If you attended the Hort show and heard any of Walt Bently's talks you heard him mention the UC pest website. Here it is.