Link to home

Conidial Germination and Appressorium Formation of Colletotrichum coccodes on Tomato Foliage

July 1997 , Volume 81 , Number  7
Pages  715 - 718

J. M. Byrne , Former Graduate Research Assistant , M. K. Hausbeck , Assistant Professor , and R. Hammerschmidt , Professor, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824



Go to article:
Accepted for publication 20 March 1997.
ABSTRACT

Conidial germination and infection processes of Colletotrichum coccodes were quantified on foliage of processing tomatoes (Lycopersicon esculentum Mill.). The abaxial surface of two opposing terminal leaflets removed from a fully expanded leaf at the 4th to 5th node was inoculated with 10-μl droplets of C. coccodes conidial suspension. Leaflets were incubated for 2 to 24 h in 2-h intervals at 25°C under high relative humidity. Explants with the conidial droplet were fixed, cleared, and preserved for microscopic observation. The percentage of germinated conidia and those with unmelanized and melanized appressoria was determined for each leaf disk. Conidial germination increased linearly with time (R2 = 0.73) (P = 0.001), maximizing (68.3%) 24 h after inoculation. The percentage of germinated conidia with unmelanized appres-soria peaked 6 h after inoculation (38.3%). Melanized appressoria formation followed a linear trend (R2 = 0.74) (P = 0.001), maximizing (62.0%) 24 h after inoculation. Infection vesicles were produced in 2.7% of conidia by 22 h, indicating successful infection.


Additional keywords: anthracnose, foliar, fruit, fungal disease, histological, latent infections, sporulation

© 1997 The American Phytopathological Society