VIEW ARTICLE

Ecology and Epidemiology

Influence of Leaf Position and Maturity on Development of Botrytis squamosa in Onion Leaves. S. C. Alderman, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824-1312; M. L. Lacy, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824-1312. Phytopathology 74:1461-1463. Accepted for publication 6 July 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-1461.

Onion plants inoculated with dry conidia of Botrytis squamosa, then incubated in a dew chamber at 20 C for 24 hr, displayed, from youngest (innermost) to oldest (outermost) leaves: increasing numbers of lesions, increasing mean lesion areas, and increasing mean lengths of infection hyphae. However, lesion area was not significantly correlated with lengths of infection hyphae within lesions after inoculation and subsequent incubation in a dew chamber at 20 C for 24 hr. In most lesions, hyphal development was restricted. Lesions developed rapidly, within 24 hr after inoculation, although the rate of development was greater on the older leaves than on the younger ones. Growth of infection hyphae within senescent tissues was about three times faster than in nonsenescent tissues on the same leaf.