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

Read More
David Doll4 CommentsOctober 11, 2013Horticulture

When to Prune First Leaf Almonds

Many are in agreement that some scaffold selection should occur on one year old almond trees. These cuts remove unwanted branches that may lead to included wood and weak branching structure in the future. Most of this pruning usually occurs in the dormant period following the first year of growth, but is this the best time?

Read More
David Doll2 CommentsJanuary 23, 2012Diseases

Pruning Wound Cankers of First Leaf Almond

Figure 1: Fungal infection of a pruning wound that occurred during first leaf pruning on Padre Pruning wound cankers have been observed on all major varieties and are the most damaging to orchards. Cankers that develop on the primary (Figure 1) or secondary scaffolds (figure 2) of young trees will lead to the loss of these scaffolds and eventual tree death. Sometimes infection occurs within the wind cracks found in the base of the scaffolds. Removal of the infected scaffold may be possible, but all of the diseased wood must be removed or the infection will remain. To stave off infection, proper structuring and tying of trees to reduce wind breakage, and pruning when the weather forecast is clear, is advised. Delayed spring pruning or late fall pruning to avoid the rains may be necessary. Pruning cuts should not be cut flush with the tree, but rather be made outside of the branch collar as this increases the rate of healing. The varieties  Aldrich, Carmel, and Padre appear to be more susceptible than Nonpareil or Butte. This disease has been noted to have a high occurrence around rivers, sloughs, and other riparian areas. It is important to note that once the tree is infected, there are no fungicide or nutrient sprays that can cure this disease. Figure 2: Fungal infection of a pruning wound made on a secondary scaffold in Padre. Control strategies for these three diseases have been difficult to develop due to the complexity of the fungi’s lifecycle. Initial infection is thought to occur through airborne spores that move in to an orchard from a residual population. Recent research has shown that uninfected trees can harbor populations of these fungi. It is thought that the fungus has the ability to infect and survive on dead bark, remaining dormant until conducive conditions occur

Read More
David Doll0 commentsJanuary 4, 2011Horticulture

Some Thoughts on Pruning First Leaf Trees

Growth inclusion and the resulting fungal infection of a five scaffold tree. I often receive questions regarding pruning first leaf trees. Many growers want to know the strategies of pruning trees. Traditionally, three scaffolds are selected, equally spaced on both the vertical and horizontal plane of the tree. This article discusses this pruning style. Currently, many growers are pruning with more than three scaffolds, and in some cases up to eight or more. Which way is better? In many ways, this decision comes down to economics. In determining if three scaffold or a multiple scaffold approach, think about how long you want your orchard to live. Pruning to fewer scaffolds will yield an orchard that has the potential to live longer than an orchard with many scaffolds. Why? Selecting scaffolds that are spaced evenly through the tree will reduce formation of canker diseases within the tree as the trees mature (15+ years). Since the scaffolds are spaced more evenly, it will take longer for growth inclusions to form, and the years of growth, and the corresponding rings of xylem, will form a stronger wood, making the tree more resistant to limb breakage. Since fungal infection of the scaffolds is delayed, orchard productivity can be maintained longer. This type of pruning is recommended for growers who don’t mind the longer wait to high productivity, but want the orchard to last a longer time (20+ years) Pruning to multiple scaffolds (5+ scaffolds) has different benefits.These trees tend to produce larger crops at a younger age. As the tree ages, the branches begin to grow together, growth inclusions form, and trees are lost to fungal infections that weaken and kill scaffolds. There is also an increased risk of wind damage and shaker damage. These trees may have to be tied longer than trees with

Read More