ISHS Acta Horticulturae 715: VIII International Symposium on Vaccinium Culture
THE INFECTION PROCESS OF COLLETOTRICHUM ACUTATUM ON BLUEBERRIES |
| Authors: | A.M.C. Schilder, P.S. Wharton |
| Keywords: | Vaccinium corymbosum, anthracnose fruit rot, ripe rot, appressorium, acervulus, infection hyphae, epidermis |
| Abstract:
The infection process of Colletotrichum acutatum, the causal agent of anthracnose fruit rot, on ripe blueberries (‘Jersey’) was investigated. Detached berries were inoculated with a drop of an aqueous suspension of C. acutatum conidia (5 x 105 per milliliter) and incubated at 25ºC under high humidity. At set intervals (4, 8, 12, 24, 36, 48, 72, 96, 108, and 120 h hours post inoculation), the epidermis under the droplet was excised, cleared and fixed. Samples were stained and observed using Nomarski differential interference contrast and confocal laser scanning microscopy. Germinated spores were first observed 4 hours post inoculation (h.p.i) and unmelanized appressoria by 8 h.p.i. By 24 h.p.i., virtually all appressoria were melanized and were showing penetration pores. Infection pegs arising from the appressoria had penetrated the epidermal cell wall by 48 h.p.i., and hyphae could be seen growing within epidermal cells. Hyphae proliferated throughout the epidermal layer and by 72 h.p.i. had begun to colonize the underlying hypodermal layers. Hyphal stromata were first observed at 96 h.p.i and these had developed into pulvinate acervuli by 120 h.p.i. These results are useful in understanding disease development and in improving timing and efficacy of disease control methods. | |
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