To Protect Your Trees in Winter Do Not Prune in the Fall or Winter

Dr. Ben Faber recently shared a blog post on the Topics in Subtropics webpage concerning the best pruning timing and practices. Importantly, while growers may feel that fall and winter — which provides more downtime — is an ideal time to prune their avocado trees that is, in fact, not the case. While light pruning can take place throughout the season to correct limb breakages or significant imbalances in a tree’s production, major pruning should only take place from January through April

The reason for this, as Dr. Faber notes, is that major pruning in fall or winter opens the tree’s canopy and makes it susceptible to frost damage. A closed canopy is much better protection during the cold weather season. Further, avocado trees do not go dormant during the cold months. Instead, they go into an inactive (slow) metabolic state that helps them better adapt to the cooler temperatures. If you conduct major pruning before the cold weather sets in, you will trigger the tree’s active metabolism and make it more vulnerable to freezes and frosts.

If you conduct major pruning in late spring and summer, it’s important to keep in mind that after the pruning is completed the newly exposed portions should be protected from sunburn with diluted latex paint.

As for the pruning process itself, avoid pruning away the stem terminals where the trees flower and bear fruit. This not only can negatively impact next year’s crop but lead to wild growth. To force lateral growth, growers can prune away buds that have begun turning into water sprouts. Pruning too late — in July — also can negatively impact next year’s flowering stage because the new buds will not have enough time to mature by August. In general, Dr. Faber recommends against removing terminals as that is a removal of potential fruiting wood and notes that if heavy pruning is necessary, it is then best to remove branches one-by-one over a series of years starting with the tallest branch or the side branch that is most crowding out other trees.

If a tree is excessively tall — making harvest more costly and dangerous — it’s best to bring the entire tree’s height down to approximately 8’. By staying at this height, growers will not trigger an excessive regrowth. And finally, Dr. Faber emphasizes that a sick tree should not be pruned until it has fully recovered and can handle the process.

Dr. Faber’s entire blog post — including an interesting flashback to early California avocado practices (when trees were either rarely pruned or stumped down to 3’ to 4’) — is available online.