Biology, management, and interactions of winter annual weeds and soybean cyst nematode

Joseph Earl Creech, Purdue University

Abstract

Certain winter annual weeds have been documented as alternative hosts to soybean cyst nematode (Heterodera glycines Ichinohe; SCN) and growth of such species has become common in no-till production fields in Indiana. Current management systems for SCN include rotation to a non-host crop and use of SCN-resistant soybean [Glycine max (L.) Merr.] varieties but fail to address winter annual weed management. This research was conducted to advance our understanding of the relationship between SCN and its winter weed hosts and to evaluate management strategies to reduce the collective impact of winter annual weeds and SCN on no-till production systems. Field surveys indicated that winter weed hosts of SCN were present in most Indiana production fields and often occurred at high densities. The most severe infestations of winter annual weeds were generally located in the southern region of the state. SCN reproduction on henbit (Lamium amplexicaule L.) and purple deadnettle (Lamium purpureum L.) was found to be common in the eastern Corn-Belt and generally occurred at higher levels in the fall than the spring. In a growth chamber experiment, SCN juveniles were able to survive a period of cold temperature inside the roots of a winter annual and continue development when transferred to warmer temperatures. Purple deadnettle was generally a more compatible host to SCN than henbit in the greenhouse. However, at high densities, henbit supported SCN reproduction at levels near those of purple deadnettle. In field experiments, SCN population densities were reduced by crop rotation but were not influenced by winter annual weed management. Fall and/or spring herbicide applications were a more effective option than wheat (Triticum aestivum L.) or annual ryegrass (Lolium multiflorum Lam.) cover crops both in terms of reducing winter annual weed growth/seed production and minimizing the potential for crop yield loss. The results of these experiments suggest that inclusion of corn into a cropping sequence is a much more valuable SCN management tool than winter weed management. In addition, control of winter annual weeds, specifically for SCN management, may not be warranted in fields with low weed density.

Degree

Ph.D.

Advisors

Johnson, Purdue University.

Subject Area

Agronomy

COinS