David Doll27 CommentsDecember 13, 2018Horticulture

Pruning Almond Trees

Pruning recommendations vary by the farmer, consultant, and even the University researcher. Some advise to prune trees hard to regenerate growth (not so much in CA anymore), some suggest that only a few limbs be removed annually, while others advocate throwing away the pruning shears. With these differences in opinion, what is the proper way to prune a tree? Young Orchards: Research has shown that reduced pruning on younger trees can lead to larger, earlier yields. This is mostly due to increased canopy that is able to produce crop. Some research has found early benefits of leaving young trees unpruned, but have found that over time, these branches will split when the crop load begins to increase leading to yield loss. Hence, some structuring of first and second leaf trees is recommended to address tight branch angles and close proximity of scaffolds, which leads to included wood and weak branches. Scaffold selection on young trees should be based on growing conditions. There is no set number that is ideal, and a farm level decision should take into account tree vigor, spacing and management practices. Heading the trees higher at planting (42” or higher) will provide more opportunity to select scaffolds, but will increase pruning time. Heading the trees too short may lead to issues with shaker head placement at maturity, leading to more bark damage. After the first year of growth, select scaffolds with distance in between and avoid scaffolds on the same plane and height of the trunk of the tree. By spacing the scaffolds vertically and around the tree, the growing limbs will be better attached, leading to less breakage. Remove steep angled limbs as these are often weaker. Limbs with a 45-60 degree angle are ideal. Avoid hard heading cuts as cutting the tree back too hard

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David Doll4 CommentsDecember 5, 2018Horticulture

Pruning: The Basics

Pruning is the practice of removing unwanted branches from the tree. Pruning can be broadly categorized to two types of cuts: heading and thinning. Heading cuts remove the terminal bud from the limb. This removes the “control center” and creates a varied response depending on the tree growth stage. Thinning cuts remove an entire limb is removed at a specified junction. This, as long as it is made in a position of low light, will often lead to little regrowth, regardless of when the cut was made. When making heading cuts, the time of the year matters. Dormant heading cuts often lead to an increase in vegetative growth the following spring. They are sometimes considered “invigorating cuts,” and can also be employed to redirect growth of a limb. In-season heading cuts will slow growth and are considered de-invigorating. These cuts slow canopy development as the tree has to redevelop the vegetative buds to push new growth. If timed appropriately, in-season heading cuts can lead to thickening of limbs and reduced breakage from wind and crop. Regardless of when they are made, heading cuts create branching. The growth response from a dormant heading cut depends on “how hard” the tree was cut back. The more proximal the cut (towards the trunk of the tree), the more vigorous the growth response. These growth responses originate out of epicormic buds, or buds that lay dormant within the wood of the tree. When these buds push, they grow without regulation and have very long internodal distances. This leads to very rapid, vertical growth that often has few fruiting positions. Thinning cuts can be made any time of the year. These types of cuts remove entire limbs and are commonly used to remove limbs from the lower canopy. Too many thinning cuts, however, can increase

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Franz Niederholzer0 commentsDecember 11, 2017Diseases

New pesticide labels available to help control pruning wound infections

Topsin® M WSP and Rally® 40WSP now have 2EE labels to protect pruning wounds on almonds (and other stone fruit trees and/or grapes) from canker disease infection. These products should be especially helpful in protecting young trees where disease infection of relatively large pruning cuts may cause extensive damage.   —-Canker diseases listed on the Topsin®M and Rally® labels—-   Topsin®M WSP Rally® 40WSP Eutypa Eutypa Cytospora Cytospora Calosphaeria pulchella Calosphaeria pulchella Lasiodiplodia theobromae Lasiodiplodia theobromae Botryosphaeria Botryosphaeria* Phomopsis Phomopsis* *suppression, only   The labels are very similar in many regards.  The following are recommended on both labels: Application within 24 hours of pruning is highly recommended. Assure complete coverage of all cut surfaces. Add a registered spray dye to better assess coverage. Additional application after about 2 weeks, especially if rain, irrigation, or high humidity occurs. Product combination (tank mixing) for best results and resistance management (Topsin M is a FRAC 1 fungicide, Rally a FRAC 3, and both have single site – high resistance risk – activity). Use of an organosilicone surfactant to improve pesticide penetration into pruning wound surfaces. (It is up to the grower to select and use a crop-safe organo-silicone with these products on pruning wounds).   There are some differences in the labels that limit how they can be used separately or combined. While the labels recommend tank mixing for best results and resistance management, consider the following: The Rally label does not allow painting the product on pruning wounds, while the Topsin M label does allow painting In addition, at the labeled rate (1.5 lb/acre), Topsin M is limited to 2 applications/year (max of 3 lbs/acre/year), while Rally is permitted a max of 3 applications/season (max of 1.5 lb/season). Therefore, if the two products are combined, painting is out and only 2 applications

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Brent Holtz0 commentsNovember 30, 2015Horticulture

Pruning First Leaf Potted Trees

Written by Brent Holtz (UCCE San Joaquin) and David Doll (UCCE Merced) The first dormant pruning of potted trees can present some difficulties when selecting primary scaffolds. Potted trees are often planted throughout the year because growers are no longer limited to planting bare root trees while they are dormant. Many successful orchards have been planted throughout the year, including in the months of July and August. These potted trees often have produced branches that have unsuitable angles, placement, or girth to develop into primary scaffolds. With this in mind, it is best to treat unpruned potted trees that are two to eight months of age as if they were recently planted bare root dormant planted trees and prune off all of their branches in the first dormant season. By doing so these trees will push new growth the following spring that should have enough branches from which to choose primary scaffolds that are spaced properly around the tree with appropriate vertical angles (~45 degrees). October – April planted trees may have to be treated differently. In this case, it may be best to not prune these trees and allow them to push the new growth. After 2-3 months of growth – or after trees have extended the new growth 12-18 inches, the trees should be pruned back similar to that of a bare root in January. This will create better branching angles while not reducing the vigor of the tree. Cutting too much off of too young of trees may stunt the tree’s growth. It may also be better to not sucker these trees until adequate girth is achieved.

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