Three Stable Types of Hydrangea Virescence that Differ in Severity in Foliage and Flowers. R. H. Lawson, Research Scientist, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Beltsville, MD 20705. F. F. Smith, Research Scientist, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Beltsville, MD 20705. Plant Dis. 64:659-661. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1980. DOI: 10.1094/PD-64-659.

Hydrangea virescence produces three distinct types of symptoms. Plants with the severe type were stunted and had small leaves, vein yellowing, and dwarfed green cymes. Vegetative growth was more vigorous in plants with the intermediate than in those with the severe type, and leaves expanded normally but showed vein yellowing. Cymes varied from completely green and dwarfed florets to mixed, with both pink and green florets. Plants with mild disease produced leaves that expanded normally and cymes that had large, all green florets. Shootlike structures proliferating from the pistils developed from some of the green florets on plants infected with mild disease. Each form of the disease remained stable for more than 3 yr through repeated transfer of the causal agent by budding to the same seedling clone. The severe form remained severe, the mild form remained mild, and the intermediate form failed to become severe, although infected plants gradually declined and died 1 or 2 yr after inoculation.

Keyword(s): hydrangea phyllody.