Source: KANSAS STATE UNIV submitted to
BIOLOGICAL AND ECOLOGICAL BASIS FOR WEED MANAGEMENT DECISION SUPPORT SYSTEMS TO REDUCE HERBICIDE USE
 
PROJECT DIRECTOR: Dieleman, A.
 
PERFORMING ORGANIZATION
AGRONOMY
KANSAS STATE UNIV
MANHATTAN,KS 66506
 
NON TECHNICAL SUMMARY: An outcome of these field experiments is to gather data relevant to Kansas on the relative competitiveness of key weed species found in corn and soybean production systems. The information will be used in a computer-based weed management decision tool that predicts the amount of crop yield loss caused by a given set of weed species and, based on economics and potential to recover lost yield, provides a suite of weed control recommendations.
 
OBJECTIVES: 1. Improve accuracy and reliability of corn crop loss estimates.
 
APPROACH: Field experiments will be conducted at the K-State Agronomy Farm - Ashland Bottoms, KS in 2001 and 2002 (2003 if required). Up to eight weed species (including giant foxtail, velvetleaf, and common lambsquarters as common species across the North Central Region) will be established at 1 plant/m of crop row in corn (76-cm row spacing) and soybean (drilled at 18-cm row spacing) at four different times of weed emergence. The experimental design is a randomized complete block for each crop with a split plot arrangement of treatments and 6 replicates. The main treatments are 4 weed emergence cohorts and subplot treatments are 8 weed species (4 annual grasses and 4 broadleaf species). Each main plot is 9.1 m long by 1.5 m wide, includes 2 corn rows or 8 soybean rows, and contains one weed emergence cohort and 8 weed species subplots. Based on weed biomass, volume, and height measures taken through the growing season and at physiological crop maturity, the relative differences in competitiveness of these weed species will be determined. A second and complementary experiment will have the same eight species established at the time of corn or soybean planting at a single moderate density (10 plants/m of crop row) in order to measure crop yield losses. The experimental design is a randomized complete block for each crop with 4 replicates. The treatments are 8 weed species with one emergence cohort. One plot is 4 m long by 1.5 m wide (1 corn row or 5 soybean rows) with a single weed species established along its length and 1 corn or 4 soybean border rows between plots. Corn grain yield will be determined by hand-harvesting ears from 3 m length of corn row for each weed species plot. Soybean seed yield will be determined by counting, harvesting, and threshing soybean plants from 3 m of 2 crop rows for each weed species plot. An MS graduate research assistant will be recruited to assist in establishing this experiment and to summarize field data collected.
 
CRIS NUMBER: 0187141 SUBFILE: CRIS
PROJECT NUMBER: KS202 SPONSOR AGENCY: CSREES
PROJECT TYPE: HATCH PROJECT STATUS: TERMINATED MULTI-STATE PROJECT NUMBER: NC-202
START DATE: Oct 1, 2000 TERMINATION DATE: Sep 30, 2005

GRANT PROGRAM: (N/A)
GRANT PROGRAM AREA: (N/A)

CLASSIFICATION
Knowledge Area (KA)Subject (S)Science (F)Objective (G)Percent
205151010602.233%
205182010602.234%
205249910602.233%

CLASSIFICATION HEADINGS
KA205 - Plant Management Systems
S1820 - Soybean
S2499 - Plant research, general
S1510 - Corn
F1060 - Biology (whole systems)
G2.2 - Increase Efficiency of Production and Marketing Systems


RESEARCH EFFORT CATEGORIES
BASIC (N/A)%
APPLIED 100%
DEVELOPMENTAL (N/A)%

KEYWORDS: corn; plant competition; weeds; emergence; soybeans; setaria; abutilon theophrasti; chenopodium album; crop yields; weed control; decision making; weed control systems; plant ecology; pesticide usage; herbicides; crop production; production systems; estimates; yield response; field studies; biomass; plant height; comparative analysis; performance evaluation; data collection; harvesting

PROGRESS: Oct 1, 2000 TO Sep 30, 2005
Data collected in 2004 as part of the multi-state research project (NC202) in 2004 was forwarded to colleagues at University of Wisconsin-Madison to be included in a summary of regional findings. A field study was initiated near Manhattan, KS in 2004 to evaluate the influence of multiple weed species emerging in one of four cohorts on corn yield loss. The study was not repeated in 2005. This was one study site among the participating states. Predominant weed species included common waterhemp and Palmer amaranth with scattered annual grasses, crabgrass and shattercane, and perennial shoots of smooth groundcherry. The first two cohorts, weed emergence with the crop (VE) and at the V2 corn leaf stage, produced enough aboveground weed biomass to impact corn yield, while few plants established in the later two cohorts, that is, weed emergence at the V4 or V6 corn leaf stages. Results were summarized in a poster presentation at the annual meeting of the North Central Weed Science Society (Jeschke et al.). Complementary studies were conducted in 2005 at the Department of Agronomy - Ashland Bottoms Research Farm south of Manhattan, KS. The goal was to evaluate the early season growth and development of corn and Palmer amaranth as well as final corn and weed seed yields in contrasting soil moisture environments and varying nitrogen rates. Within a dryland or furrow irrigated soil moisture environment, monoculture corn or Palmer amaranth plots were established, as well as corn-Palmer amaranth mixtures including 1, 4, and 8 pigweed plants/m of corn row. Nitrogen rates were 0, 112 and 224 kg N / hectare applied prior to planting. Destructive harvests of corn and Palmer amaranth were taken every 3 to 5 days beginning 20 days through 60 days after planting (tasseling). In the high nitrogen rate treatments across soil moisture environments, no differences in corn height, leaf number and leaf area were observed when corn was grown alone or with Palmer amaranth. Height, leaf number, and leaf area of Palmer amaranth grown alone were greater than Palmer amaranth grown with corn. Corn effectively suppressed Palmer amaranth growth during the early season and corn easily tolerated the presence of Palmer amaranth through to tasseling. As nitrogen rates increased, both corn and Palmer amaranth had higher levels of nitrogen in their total leaf tissue. As part of this study, a crop-weed simulation model, ALMANAC, is being parameterized and used to predict crop and weed growth in response to water stress and varying nitrogen rates. Predictions will be compared to previously collected field data documenting weed growth and crop yield loss.

IMPACT: 2000-10-01 TO 2005-09-30 Computer-based weed decision support systems require biological information on relative competitiveness among key weed species and their response to differing environmental conditions. The semiarid environment in Kansas makes corn yield predictions at the beginning of the season difficult even though that information is the basis for making in-crop weed management decisions. Determining differences in early season growth and development of the crop and weed in dryland vs. irrigated environments could improve the prediction of crop yield potential and losses. Through understanding their real impact on crop growth and yield, we can validate the information in our decision support system, and improve weed management decision-making in Kansas.

PUBLICATION INFORMATION: 2000-10-01 TO 2005-09-30
Jeschke, M.R., D.E. Stoltenberg, J.A. Dille, G.A. Johnson, G.O. Kegode, S.Z. Knezevic, S.M. Hock, and C.L. Sprague. 2005. Validation of WeedSOFT crop-yield loss predictions for cohorts of mixed-species weed communities. Proc. North Central Weed Sci. Soc. Abstr. 60:66 (Dec. 2005).

PROJECT CONTACT INFORMATION
NAME: Dieleman, J. A.
PHONE: 785-532-7240
FAX: 785-532-6094