Almond husk rot is a fungal disease of the nut shell of almond trees. It can cause significant losses in almond crops, but it can also sometimes affect backyard trees. Understanding the basics of structure rot and identifying the factors can help you control this disease that can permanently destroy the fruit wood on your tree.
What is Hull Rot?
Nut yields are often severely reduced by plow rot, and worse, the disease will destroy and die infected wood. Powdery mildew can be caused by one of two types of fungus: Rhizopus stolonifera causes black spores inside the pod after bursting, and Monilinia fructicola produces tan spores inside and outside the pod after bursting. Before you can see the spores, you may notice that the leaves on a young, infected branch are wilting and then dying.
Managing Hull Rot in Nuts
Ironically, it is the abundance of water and nutrients that you think helps your almond tree grow well that invites rot. Agricultural researchers have found that exposing almond trees to moderate water stress—in other words, slightly reducing water—a few weeks before harvest, around the time the pods split, can prevent or significantly reduce rot.
It sounds simple enough, but you actually need to use a pressure bomb to make the water pressure work as a way to stop the rotting nut hulls. It is a device that measures water pressure by sampling leaves. The researchers say that simply reducing the water by an arbitrary amount will not work. The slight pressure of the water should be measured. This can be difficult if you have deep soil that holds water well. It may take a few weeks to reach the desired tension.
The effort and cost of a pressure bomb may be worth it, because plow rot is a devastating disease when it engulfs a tree. It destroys the fruiting wood and can even destroy and kill the entire tree. Infected bushes also become an excellent habitat for the navel orange worm.
In addition to causing water stress, avoid over-fertilizing. Too much nitrogen can lead to a fungal infection. Reducing watering is the most effective way to manage or prevent nut hull rot in nuts, but you can also use fungicides for almond varieties that have some resistance. Among them are Monterrey, Carmel and Fritz.