Noninfectious bud failure of almonds in California the nature and origin

Noninfectious bud failure (BF) is a disorder caused by a peculiar genetic abnormality characteristic of certain almond varieties. It is a serious economic problem in that many thousands of trees have had to be replaced and at least one variety, Jordanolo, is being eliminated because of its susceptibility to BF. The disorder is expressed by the failure of vegetative buds to grow in the spring. This, along with other roughbark characteristics, results in a distinctive growth pattern sometimes also described as “crazy-top.” Trees do not die but production in individual trees is reduced in proportion to the severity of the symptoms. Experimental work on the disorder can be divided into two basic problems discussed here in two separate articles. One concerns the nature of the disorder and the origin of the BF condition, and is studied in the first article. The other (studied in the second article) involves the sporadic appearance of BF in such important varieties as Nonpareil, and deals with practical methods to identify and control it.