The nature and development of noninfectious bud failure of almonds
AuthorsE. E. Wilson
Richard D. Schein
Authors AffiliationsE. E. Wilson was Professor of Plant Pathology and Plant Pathologist in the Experiment Station, University of California, Davis; Richard D. Schein was Formerly Research Assistant in Plant Pathology, University of California, Davis. The phases contributed by the junior author were originally part of a thesis presented to the Graduate Division, University of California, at Davis, in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
Hilgardia 24(18):519-542. DOI:10.3733/hilg.v24n18p519. April 1956.
The almond-tree disorder known as almond bud failure occurs to a moderate extent in the Nonpareil and Peerless varieties, but is widespread in the Jordanolo variety chiefly in the Sacramento Valley. Other varieties thought to be affected are the Texas and the Jubilee, although this has not yet been verified.
The primary symptom of the disorder is the failure of buds to grow. Secondary symptoms include excessive shoot production, delay in blossoming, and bark necrosis.
Tests of Nonpareil, Peerless, and Jordanolo buds and scions have failed to show that the disorder is infectious. Bud failure, however, developed in the growth from a high percentage of buds and scions from affected trees. It is concluded, therefore, that the disorder is bud-perpetuated.
Bud-failure symptoms develop in scions growing on different rootstocks, including peach, bitter almond seedlings, and the Texas almond seedling.
There is some evidence that vegetative propagation tends to increase the manifestation of symptoms in the Jordanolo variety. Severe pruning of affected trees also apparently tends to increase the severity of symptom expression.
Almond bud failure is transmitted through the seed. Fourteen per cent of one lot of seedlings produced from seeds of affected Nonpareil almond trees exhibited loss of buds and bark necrosis within 2 to 4 years after planting.
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