VIEW ARTICLE

Ecology and Epidemiology

Effect of Temperature and Moisture on Parasitization of Heterodera schachtii Eggs by Acremonium strictum and Fusarium oxysporum. Elizabeth A. Nigh, Former graduate research assistant, Department of Nematology and Plant Pathology, University of California, Riverside 92521, Present address of senior author: Arizona Western College, Agriculture Department, P.O. Box 929, Yuma 85364; Ivan J. Thomason(2), and S. D. Van Gundy(3). (2)(3)Professors, Department of Nematology and Plant Pathology, University of California, Riverside 92521. Phytopathology 70:889-891. Accepted for publication 4 March 1980. Copyright The American Phytopathological Society. DOI: 10.1094/Phyto-70-889.

Parasitization of Heterodera schachtii eggs by Acremonium strictum and Fusarium oxysporum occurred after 200 degree-days growth of the nematode at 24 C and increased with time to 58 and 46% by A. strictum and F. oxysporum, respectively. Parasitic activity of A. strictum was greater at 24 C than at 28 C, that of F. oxysporum was similar at 24 and 28 C and little parasitism was expressed by either fungus at 20 and 32 C. A. strictum was parasitic when soil moisture was near saturation, but not when it was held near wilting point levels. The reverse was true for F. oxysporum.