University of California

The action of Phomopsis californica in producing a stem-end decay of citrus fruits


Monir Bahgat

Author Affiliations

Monir Bahgat was Thesis submitted in partial fulfillment of the requirement for the degree of Doctor of Philosophy, University of California.

Publication Information

Hilgardia 3(6):153-181. DOI:10.3733/hilg.v03n06p153. April 1928.

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The aim of this investigation was to study the parasitism of Phomopsis californica Fawc., especially as to the manner in which the organism affects the different tissues of citrus fruits.

This fungus is similar to Phomopsis citri, which causes stem-end rot and melanose in Florida. P. californica was found by Fawcett (1922, 1924, 1926) to be the causal agent of decorticosis (shell bark) of lemon trunks and of a leathery, pliable stem-end rot of citrus fruits.

Of the various citrus fruits inoculated, lemons proved to be the most susceptible to this decay. The stem end, which is the usual place for beginning of decay under natural conditions, was also found to be the ideal place for infection under laboratory conditions. Wounds or punctures always facilitated infection.

It was noted that certain tissues of the lemon fruit were readily invaded by the fungus, while others remained free from invasion. The cells of the loose parenchyma tissues of the inner portion of the rind, known as the albedo, and those forming the axis of the fruit, known as the core, as well as the vascular bundles, were the elements most commonly attacked.

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Bahgat M. 1928. The action of Phomopsis californica in producing a stem-end decay of citrus fruits. Hilgardia 3(6):153-181. DOI:10.3733/hilg.v03n06p153
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