Ask Your PCA: What do you hope to accomplish with a dormant spray for almonds?

Issue Date: January 14, 2009

By Barry Malm, Dos Palos PCA, CAPCA member

A dormant spray of oil, a copper fungicide and an insecticide is helpful in controlling a number of pest and disease problems in almonds. This combination of materials can help to control mites, scale, peach twig borer and some bacterial diseases.

But you have a fairly narrow window to do your dormant season spray.

It has to be late enough in the winter that the cold has caused all the leaves to drop off the trees, and the cold weather has helped harden off the green wood. This reduces the risk of a phytotoxic reaction to the spray.

But it has to be early enough to be sure that you're not putting the oil on too close to the new growth.

That usually means that I will be looking to get dormant sprays on some time in January.

Some growers do a dormant season spray every year, but more and more growers are thinking about doing without it to save money. It is not cheap. If you have someone come in to spray your orchard it will cost you $20 or more an acre, and then there is the cost of three different materials.

In deciding whether to put on a dormant spray it is good to keep in mind whether you had a problem with mites last summer. Most growers had mite problems last year so it is probably a good idea to put on a dormant spray this year.

One approach to consider is to skip a dormant spray one year if you didn't have much mite pressure, and then come back and spray again the next dormant season.

Another approach is to try to apply materials to control pests along with a zinc application in the fall, rather than with a dormant spray in January. If no insecticide is applied during the fall or dormant spray then an insect growth regulator may be applied during the bloom spray.

Most almond growers apply a miticide in late April or early May. The goal of the dormant season application is that the oil is effective enough against the mite eggs to keep the pests under control until then.

The insecticide can catch some of the peach twig borer in the bark of the tree during the dormant season.

Good sanitation to clean the mummies out of the orchard is probably the best thing you can do during the dormant season to control navel orangeworm. Some growers are also controlling navel orangeworm with an insect growth regulator with their miticide spray.

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