Report from 2005
START: 01 JUL 2000 TERM: 30 JUN 2003 FY: 2003 GRANT YR: 2000
GRANT AMT: $114,494
INVESTIGATOR: Curran, W. S.; Calvin, D. D.
PERFORMING INSTITUTION:
CROP & SOIL SCIENCES
PENNSYLVANIA STATE UNIVERSITY
208 MUELLER LABORATORY
UNIVERSITY PARK, PENNSYLVANIA 16802
IDENTIFYING FIELD PARAMETERS FOR SUCCESSFUL POSTEMERGENCE WEED MANAGEMENT IN CORN
NON-TECHNICAL SUMMARY: Successful POST weed management in corn could provide improved control of certain weeds, reduce some costs associated with corn weed control, be environmentally positive, and is a step toward a more integrated weed management system based on pest identification and severity. Identifying field specific characteristics that lead to successful POST weed management in corn is the focus of this project.
OBJECTIVES: 1. Determine the effect of soil disturbance on weed species emergence rate and duration and develop a predictive model for weed emergence - This experiment will help define weed emergence periods for common annual weeds in the Northeast. These data will be used to develop a weed emergence model, which in turn, will support a decision guide that will help predict the success of total POST weed control programs. This study will be conducted in years two and three. 2. Determine the effect of weed density on single-pass POST weed control and corn grain yield. - This experiment will help determine the impact of weed density and weed control timing on corn grain yield with a single POST application of a non-residual herbicide. These data will be used to develop a decision guide that will help predict the success of total POST weed control programs based on critical application period to avoid yield loss. This objective will be conducted in years two and three. 3. Evaluate the effectiveness of a total POST weed control program over a broad range of conditions. - This study will be conducted over three states in a range of conditions to identify characteristics for success and/or failure. This objective will be conducted in years one and two. 4. Develop a decision guide for the probability of a successful total POST herbicide program in corn and need for residual herbicide(s) at a given location. - A user-friendly decision guide which incorporates data from the previous three objectives. To be conducted throughout the three years.
APPROACH: Objective 1 will be conducted at two locations in Pennsylvania, one location in Delaware, and one in New Jersey. Weed species will include six to ten annual weeds that are representative of common weeds of the Northeast. Field locations previously in a summer annual crop or fallow will either be spring tilled or no-till. The experiment will be arranged as a randomized complete block design with 6 replications. Individual plot size will be 2 by 5 meter. Weed emergence by species will be monitored every ten days by counting all weeds, by species prior to chemical removal. Detailed weather information including air and soil temperature and rainfall will be collected throughout the duration of the experiment. Weed emergence functions will be estimated for each location and compared by regressing percentage of the weed population emerged against the number of degree-day accumulated since the crop was planted. A weed emergence model will be developed with this data. Objective 2 will be conducted at two locations in Pennsylvania, two locations in Delaware, and one in New Jersey. Glyphosate-resistant corn will be planted into a prepared seedbed in early May. The three weed densities will be established by seeding barnyardgrass (Echinochloa crus-galli), and smooth pigweed (Amaranthus hybridus), at three different seeding rates. Weed removal timings will be at 2, 4, 6, or 8-collar corn stage and full season competition. A weed-free check will also be included. Weed density by species, weed height, and weed leaf number will be determined 7, 14, and 21 days after each herbicide application timing. At twelve weeks after planting, above-ground weed biomass separated by species will be collected. Corn grain yield will be machine harvested from 2 to 3-rows/plot following physiological maturity of the crop. Objective 3 will be conducted at a wide variety of locations in an attempt to experience a range of soil types, rainfall, weed species, and crop management practices. This study will include fourteen treatments utilizing glyphosate-resistant corn. This series of treatments will examine the need for residual herbicides when a total POST program is used. For comparison purposes, a weedy and weed-free check will be included. Treatments will be arranged in a randomized complete block design with four replications. Plots will be 4 rows wide and 8 meters long. Plot size will allow for ease of establishment by county agents, backpack herbicide applications, as well as facilitate hand-harvesting. Objective 4 will develop a decision guide designed to identify situations where total POST programs are most likely to be successful. The decision guide will provide two levels of information. The first decision level will help define whether to use a preemergence or POST system. For the second level, if a post system is selected, the need for residual control or a second POST application will be assessed. Information on weed species composition, weed species density, tillage system, soil type, rainfall, planting date, rate of degree day accumulation and herbicide program will be used to predict the likelihood of each program's success at a specific location.
PROGRESS: 2000/07 TO 2003/06
Across the United States, the most frequent herbicides used for weed control
in corn are soil-applied, preemergence products. Although preemergence herbicides
are often considered an important tool in weed management, there are number
of concerns associated with them. One possible alternative is to integrate postemergence
weed control into weed management systems. In order to evaluate the potential
success of single postemergence applications, three different experiments were
conducted between 2000 and 2002 across multiple northeastern states. The objectives
of these studies were to develop prediction models for weed emergence across
geographic locations, examine the impact of postemergence herbicide application
timing and program across multiple locations, and to evaluate the impact of
both weed density and time of weed removal on corn grain yield. The ability
to predict weed emergence across geographic location using a soil degree-day
scale varied with weed species with the coefficients of determination for the
predictive emergence model ranging from 0.67 to 0.88, depending on species.
Most weed species had two distinct peaks of emergence. In terms of periodicity,
common ragweed had one of the shortest emergence periods, while redroot and
smooth pigweed had one of the longest periods of emergence. In the weed density
experiment, at low weed densities, application timings ranging from V2 to V8
corn provided corn yields similar to the weed-free plots. At higher weed densities,
however, the V4 application timing provided the most consistent and highest
yielding results. In the application timing experiment at multiple locations,
the V3/4 timing was more effective than the V2 timing when averaged over treatment.
Glyphosate alone was impacted the most by timing, with the V2 treatment having
less effect on weed biomass, compared to the other treatments. The glyphosate
mixtures and the nicosulfuron-based treatment were equal at the V3/4 timing
when averaged across location. Problem weeds with some total post treatment
locations included quackgrass and yellow nutsedge in Maine, common cocklebur
and horsenettle in Delaware, large crabgrass and yellow foxtail in Massachusetts,
and common ragweed and giant foxtail at several locations. Regardless of treatment,
the untreated check had at least 5 times more weed biomass than any herbicide
treatment regardless of timing. Excluding the weedy check, corn grain yield
ranged from less than 56 kg/ha to more than 224 kg/ha depending on location.
Yield in the glyphosate alone V2 treatment was less than the other V2 treatments
that included residual herbicides. These experiments demonstrate that single
postemergence applications can be successful, but are dependent on weed species
and density as well as herbicide program.
IMPACT: 2000/07 TO 2003/06
These results show that periodicity in weed emergence varies by species, and
that soil degree-days can be used to predict seedling emergence during the growing
season. In this project, spring tillage did not greatly influence emergence
periodicity, but did affect seedling numbers. Knowledge of weed emergence periodicity
in relation to crop planting, growth, and herbicide application could greatly
improve efficacy of postemergence weed control. Weed density will also influence
successful postemergence weed control with higher weed densities reducing the
critical period for a single postemergence herbicide application. At the same
time, these experiments demonstrated that single postemergence applications
can be successful, but are dependent on weed species and density as well as
herbicide program. Future research should identify other factors that may help
improve the success of a single postemergence strategy such as soil moisture,
soil type, and time of crop planting.
PUBLICATIONS: 2000/07 TO 2003/06
1. Curran, W.S., M.J. VanGessel, and B. A. Majek. 2001. Success of total post
weed control in northeastern corn. Proc. NEWSS 55:30. Curran, W.S., M.J. VanGessel,
and B.A. Majek. 2002. Success of Total Post Weed Control in Northeastern U.S.
Corn - 2nd Year Results. Proc. NEWSS 56:18.
2. Myers, M.W., W.S. Curran, D. Mortensen, B.A. Majek, A.O. Ayeni, and M.J.
VanGessel. 2002. Effect of Soil Disturbance on Weed Species Emergence. Proc.
NEWSS 56:5.
3. Scott, B.A., M. J. VanGessel, M.W. Myers, W. S. Curran, and B.A. Majek. 2002.
Impact of weed density and removal timing on single-pass postemergence weed
control and corn grain yield. Proc. NEWSS 56:96.
4. M.W. Myers, W.S. Curran, D.A. Mortensen, M.J. VanGessel, and B.A. Majek.
2002. Effect of soil disturbance and geographic location on weed species emergence.
12th EWRS Symposium, Wageningen Netherlands, ISBN #:90-6754-671-2.
5. Lingenfelter, D.D., W.S. Curran, M.J. VanGessel, and B.A.Majek. 2003. Comparison
of a nicosulfuron-based and glyphosate-based program for post weed control in
corn. Proc. NEWSS 57:10.
6. Myers, M.W., W.S. Curran, D. Mortensen, D.D. Calvin, M.J. VanGessel, B. Scott,
B.A. Majek, and A.O. Ayeni. 2003. Periodicity of weed emergence and implications
for weed management in corn. Proc. NEWSS 57:124.
7. Scott, B.A., M.J. VanGessel, M.W. Myers, W.S. Curran, and B.A. Majek. 2003.
Impact of weed density and removal timing on single-pass postemergence weed
control and corn grain yield. Proc. NEWSS 57:96.
8. Myers, M.M. 2003. Assessing the potential for single pass postemergence weed
control in corn. M.S. Thesis., Dept . Crop and Soil Sci., College of Agric.
Sci., Penn State University, University Park.
PROJECT CONTACT:
Name: Curran, W. S.
Phone: 814-863-1014
Fax: 814-863-7043
Email: