On-farm sampling of weed management systems in tomato production

David Edgar Hillger, Purdue University

Abstract

Weed species respond to the cumulative effect of multiple practices employed within weed management systems. However, this response is rarely studied at the system level and the relationship between weed communities and management systems in crops is not well understood. We used a questionnaire, on-farm sampling, and multivariate analyses to assess the relationship between management systems and weed communities in tomatoes. Growers provided detailed information about their management practices from 1998 to 2004 through the questionnaire and on-farm interviews for 59 fields which were sampled for emergent weeds and weeds in the soil seedbank in 2003 and 2004. Minimum variance and non-metric multidimensional scaling ordination were used to identify five management systems based on the questionnaire. The systems differed primarily in the use of irrigation and in the extent to which hand weeding was used to control weeds. Conventional processing tomatoes growers typically used multiple applications of herbicides with very little hand weeding. Fresh market growers used a combination of herbicides, plastic mulch and hand weeding to control weeds, market growers that followed organic weed control practices used higher amounts of hand weeding and suppressive cover crops as a replacement for herbicides in weed control. Canonical correspondence analysis and species indicator analysis revealed strong associations of weed species in the seedbank and emerged populations with the objectively identified production systems. Several species displayed association for different production systems. Emergent populations of bamyardgrass, goosegrass, yellow nutsedge, smartweed spp., redroot pigweed and common ragweed were strongly associated with the organic fresh market system. Redroot pigweed and goosegrass were associated with the seedbank population in the organic fresh market system. In both the emergent and seedbank studies, common purslane was closely associated with the nonirrigated fresh market system while irrigated fresh market systems were associated with fall panicum. Emergent populations of giant ragweed, ivyleaf morningglory, prickly sida, and velvetleaf were associated with the two processing systems. This work clearly demonstrates the importance of research that looks beyond a single management practice or a single weed species to the combined weed management system and how it affects weed communities.

Degree

Ph.D.

Advisors

Gibson, Purdue University.

Subject Area

Agronomy|Ecology

COinS