pnut pnut Peanut Science 0095-3679 0095-3679 American Peanut Research and Education Society 10.3146/i0095-3679-13-2-6 Articles Temperature Effects on Germination and Comparative Morphology of Conidia for Thai and USA Isolates of Cercosporidium personatum1,2 Tharmmasak Sommartya and M. K. Beute Visiting Assistant Professor and Professor, respectively, Department of Plant Pathology, Kasetsart University, Bangkok, Thailand, and Department of Plant Pathology, N C State University, Raleigh, NC 27695–7616

1Paper No. 10349 of the Journal Series of the North Carolina Agriculture Research Service Raleigh, NC 27695–7601. Use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of the products named nor critism of similar ones not mentioned.

2This work was supported in part by the Peanut CRSP, USAID grant no. DAN-4048-G-SS-2065–00. Recommendations do not represent an official position or policy of USAID. Authors wish to express gratitude to P. Backman, F. Shokes and D. Smith for aid in supplying pathogen isolates.

 7 1986 13 2 67 70 16 8 1986 American Peanut Research and Education Society 1986 American Peanut Research and Education Society Abstract

Ten isolates of Cercosporidium personation (Cp) were collected from seven geographical areas in Thailand and the USA. Four USA and 6 Thai isolates were cultured on a susceptible peanut genotype, NC 3033, to produce conidia for all studies. Conidial germination was determined after 12, 24, and 48 h at 16–36 C. Percent germination of conidia for all populations were greatest at 16–20 C. At 30 and 32 C, 58 and 22% of conidia from Thai isolates germinated, respectively. Only 33 and 6% of conidia from USA isolates germinated at 30 and 32 C. Only Thai isolates germinated at 36 C. No differences were observed among isolates for conidial length or number of septa per conidium. Conidia of all isolates, however, were longer and had more septa than previously reported. Conidial length in this study ranged from 16–90 um and number of septa per conidium ranged from 1–11. Conidia with furcate branching were observed with both Thai and USA isolates. Forked conidia produced normal germtubes either intercalary or terminally and all three terminal cells produced germ tubes.

 Key Words Arachis hypogaea; , late leafspot; , spore germination