Influence of Pea Cropping History on Disease Severity and Yield Depression. L. Bødker, Danish Institute of Plant and Soil Science, Research Centre for Plant Protection, Lottenborgvej 2, DK-2800 Lyngby, Denmark. N. Leroul, and V. Smedegaard-Petersen. Danish Institute of Plant and Soil Science, Research Centre for Plant Protection, Lottenborgvej 2, DK-2800 Lyngby, Denmark, and Department of Plant Biology, Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark. Plant Dis. 77:896-900. Accepted for publication 26 April 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0896.

Field plot studies at five experimental sites were conducted during 1989-1991 to examine the influence of pea cropping history on disease severity and yield depression in peas (Pisum sativum). A modified greenhouse test for estimating the degree of infestation of fields proved to be a good predictor of disease severity. Several major pathogens were involved in the disease complex, and the total number of colonies isolated from the root systems and epicotyls appeared to be correlated with a disease severity index. In soils not previously cropped with legumes, two successive pea crops resulted in a slight yield decrease in the second-year crop. In naturally infested soils, the yield reduction was more pronounced. Aphanomyces euteiches was recovered from plants after two pea crops in 3 yr. This study suggests that cultivation with a conventional moldboard plow to a depth of about 20 cm cannot eliminate the increase in infestation of the root rot complex caused by a single pea crop. In soils with severe infestation of root rot pathogens, plant height seems to be closely correlated with the yield of dry peas. Aboveground symptoms, such as stunted plant growth, yellowing, and wilting, were only noticed for severely affected plants.

Keyword(s): Fusarium.