Gummosis

gummosis [‚gə′mō·səs]

(plant pathology)

Production of gummy exudates in diseased plants as a result of cell degeneration.

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Gummosis 

a disease predominantly of arboreal plants (such as stone-fruit crops, citrus, and mulberry) and more rarely herbaceous plants (such as cotton and sesame). The disease is characterized by the exudation of gum, a viscous, sticky amber-yellow or brown liquid that forms in the cells of the bark and lignin as a result of the dissolving of the cell membranes.

Gummosis is caused by poor cultivation conditions, injuries, frost crack, and damage by insects and microorganisms. The most harm is caused by cotton gummosis, which is encountered in all cotton-growing regions. This disease infests the aboveground organs and is accompanied by the appearance of grayish oily spots covered by gum. It is caused by the bacteria Xanthomonas malvacearum. The sources of infection include contaminated seeds and plant remains. Heavily infested shoots die, the leaves and fruiting elements turn yellow, dry out, and drop off, the stems become thin and crack, and the bolls rot.

The measures for combating cotton gummosis include the preparation of healthy seed stock, destruction of the post-harvest residues, late autumn plowing, and the disinfection of seeds. The measures for combating gummosis in stone-fruit trees are chiefly preventive and include correct farming practices, protection against sunscald and frost cracks, and correct pruning of the trees. For citrus, the measures include good soil drainage, spraying with Bordeaux mixture, and treatment of wounds.

REFERENCES

Babaian, A. A. Gommoz khlopchatnika. Yerevan, 1963.
Slovar’-spravochnikfitopatologa, 2nd ed. Edited by P. N. Golovin. Leningrad, 1967.

A. A. BABAIAN