Impacts of Chaff Collection or Chaff Plus Straw Collection at Harvest to Improve Weed Control

Final report for SW16-010

Project Type: Research and Education
Funds awarded in 2016: $250,000.00
Projected End Date: 02/28/2020
Grant Recipient: Oregon State University
Region: Western
State: Oregon
Principal Investigator:
Dr. Judit Barroso
Oregon State University
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Project Information

Abstract:

Global wheat production is threatened by the escalating selection of herbicide resistant weed populations. The continuing evolution of herbicide resistance in major crop weeds is a driving force to develop new weed control strategies in field crops and also to preserve the utility of herbicides. However, weeds are not only a threat in conventional agriculture but also a threat to organic agriculture and often cause these systems to fail. More sustainable practices that reduce the dependence of herbicides or soil tillage are needed to control weeds in crop production systems.
In Australia, weed scientists have had promising results with practices that target collection or destruction of weed seeds at grain harvest (Walsh et al., 2013). These practices include the use of chaff carts, bale direct systems, the Harrington seed destructor (HSD), and narrow windrow burning among others. This project will concentrate on the potential benefits of the use of chaff carts and bale direct systems to reduce weed infestations in wheat-production systems in the Pacific Northwest (PNW). The HSD has produced good results, but the cost of a single unit is beyond this project’s budget and its efficacy to control weeds is comparable to that of a chaff collection system. Narrow windrow burning is a practice with a high risk of causing fire and detrimental effects on air quality. The use of chaff carts and bale direct systems are two harvest practices that have not yet been adequately evaluated in the PNW. Their efficacy to control weeds is unknown because the proportion of weed seed per species collected by the combine and ejected with the chaff or straw has not been investigated. The objectives of this study are: 1) Evaluate chaff collection and chaff plus straw collection at harvest to reduce weed species density and dispersion, 2) Evaluate seed production, seed height, and seed retention of important weed species at harvest, 3) Determine the effects of chaff or chaff and straw removal on soil organic matter and moisture content, and 4) Disseminate knowledge gained from the research via extension activities oriented to farmers, ag-professionals, students and stakeholders.
Field experiments with two treatments and three replications were established on naturally occurring weed-infested areas at each participating farm (three farms in Oregon and one farm in Washington). The two treatments were harvesting with the combine alone (control treatment) and harvesting with either a chaff cart or a bale direct system behind the combine. We did not expect participating farmers to work with both practices on the same farm because the adoption of one or the other practice depends in many cases on their residue management system.
In addition to the on-farm experiments, we conducted supplemental experiments on university research farms. The research farm experiments applied both practices, i.e. chaff cart and bale direct system, with four replications. In all experiments (commercial and research farms), weed infestations were characterized and evaluated before crop harvest, and the following spring for three years to determine the efficacy of each harvest practice. Seed production, seed height, and seed retention were measured to determine the quantity of seed per species that were collected by the combine. In the research farm experiments, the soil organic matter and moisture were measured monthly to look for differences between treatments.
The final goal of this project was to determine the ability of chaff collection and chaff plus straw collection practices during harvest to reduce weed infestations over time and determine some recommendations to maximize the effectiveness of these practices. 

Project Objectives:

1) Evaluation of chaff collection and chaff plus straw collection practices at harvest to reduce weed species infestation
An experiment was established in naturally infested areas on participating farms in spring 2016. The experiment was a randomized complete block design with two treatments on approximately one acre of land. The two treatments were 1) harvesting with the combine alone (control treatment) and 2) harvesting using a chaff cart or a bale direct system behind the combine. A similar experiment was established on two research farms in spring 2016. The research farm experiments, in addition to natural weed infestations, had an artificial infestation of one important weed species not already in the seedbank to evaluate weed dispersion in addition to density. The research farm experiments allowed us to evaluate both practices at the same location. The infestation in each plot was monitored annually. This objective allowed us to assess the ability of chaff carts or bale direct systems to reduce weed infestations in density and area over time. This objective started in spring 2016 and finished by summer 2019.

2) Evaluation of seed production, seed height, and seed retention of important weed species at harvest
In the same fields established for objective 1, we evaluated seed production, seed height, and seed retention rate of the dominant weed species at each experimental site. This objective allowed us to determine the optimal cutting height to maximize control depending on the weed species and determine the potential percentage of control per species if none of the weed seed harvested is returned to the seedbank. This objective started in summer 2016 and was completed in the fall of 2019.

3) Effects of chaff or chaff and straw removal on soil organic matter and moisture content
The organic matter and soil moisture content was monitored in one of the research farm experiments from June 2016 to February 2020. This objective allowed us to determine differences between residue removal treatments in soil organic matter and soil moisture content.

4) Conduct several extension activities oriented to farmers, ag-professionals, students and stakeholders
Educational materials were developed to instruct producers on the use of chaff carts and bale direct systems to improve weed control and enhance agricultural sustainability. Scientists participated in seminars and conferences to reach larger audiences. This objective began in the fall of 2016 and will finish by March 2020 and beyond.

Cooperators

Click linked name(s) to expand
  • Paul Carter
  • Andrew Hulting
  • Drew Lyon
  • Carol Mallory-Smith
  • Darrin Walenta
  • Michael Walsh
  • Stewart Wuest

Research

Hypothesis:

Our hypotheses were:

1) That the use of chaff carts or bale direct systems would help to reduce weed infestations in winter wheat cropping systems of the PNW

2) That the efficacy of these practices would depend on several factors such as, weed species present, harvest time, and cutting height.

Materials and methods:

1) Evaluation of chaff collection and chaff plus straw collection practices at harvest to reduce weed species density and dispersion.

In spring 2016, we established experimental plots in wheat fields of Oregon farmer collaborators. In spring 2016, we also established the experiment at CBARC research farm (see Appendix A for experimental design on cooperating and research farms). In the fall 2016, we established the experiment at Hyslop research farm. In spring 2017, we established the experiment in Washington that we failed to establish in 2016, where we compared the bale direct system to no bailing. In the selected areas, we marked the treatment plots and determined the species to study at each farm. At both research farms, in addition to evaluating the natural infestation, we seeded feral rye (Secale cereale) at CBARC (48037 Tubbs Ranch Road, Adams, OR) and downy brome (Bromus tectorum) at Hyslop (3455 NE Granger, Corvallis, OR) in the fall 2016.
In all experiments, the initial infestation was sampled using two different methodologies:
1) Continuous method: The evaluator walked the plots in parallel transects to the longest plot direction (simulating a posterior pass of the combine) carrying a handheld computer with built-in GPS receiver (Yuma2® Rugged Tablet Computer, Trimble, Sunnyvale, CA, USA) that was used to partition each plot into numerous cells (6 × 3 m (20 ft x 10 ft)) thanks to the customized grid background. In each cell, percentage of weed cover per species was evaluated (Figure 1).
2) Discrete method: Using the same evaluation units (cells – defined by the previous methodology) for the experiment at CBARC and once per two evaluation units in the participating farms, the evaluator threw a sampling frame (0.5 m x 0.5 m) randomly where he/she counted the number of plants per weed species and estimated the percentage cover per species as well (Figure 2).

Appendix A - Experimental design

Figure 1 and 2

Each spring, all plots were sampled using the discrete method described above. In addition, when plots were in crop, they were also sampled at harvest using the discrete and continuous sampling method. At participating farms, the experimental plots followed the cropping system of the farmer. However, research farms followed an annual cereal cropping system to harvest each year. When a fallow year or non-wheat crop occurred in the commercial experiments, spring weed evaluations were still conducted to track the change of the infestation during that year. The weed evaluations before and after the harvest treatments have been used to determine increase or decrease of weed infestation in the different fields and harvest treatments, and to determine differences in weed dispersion in those species not present in the soil seedbank before the beginning of the project at the research farms. Unfortunately, we were not able to conduct a full experiment in Hyslop in spring 2017 and in spring 2018 after reseeding the plots in the fall 2017 due to low downy brome establishment. In 2019, wild oat (Avena fatua) was seeded at the beginning of plots (6 m x 80 m) in Hyslop to study seed dispersion with the combine.
The bale direct system treatment and control treatment on commercial farms were conducted with the farmer’s equipment. A chaff cart prototype was built to collect chaff at participating farms and CBARC with CBARC’s combine.
Differences in infestation abundance between treatments were analyzed with analysis of variance with repeated measurements. Unfortunately, we could not evaluate feral rye dispersion at the CBARC farm because the farming practices used to seed the crop in spring 2017 controlled it completely.

2) Evaluation of seed production, seed height, and seed retention of important weed species at harvest
During the summers of 2016, 2017 and 2018, close to the experiment areas described for Objective 1, starting one month before harvest, weekly, we collected 10 plants per weed species to estimate seed production and seed retention at harvest time. Each plant was bagged independently in a paper bag for later processing. At the laboratory, different protocols per weed species were followed to count or estimate the number of seeds per plant. Plant height and seed height were measured from ten plants per species at two different dates before or during harvest. The response of seed retention to harvest timing was studied with linear and non-linear regression models. In order to establish a common winter wheat harvest date in this study, and considering that July 15 is indicated in the USA-NASS report (USA-NASS, 1997) as the beginning date of harvest season for Oregon and Washington, July 15 was selected as a reference date for the beginning of winter wheat harvest. However, August 1 was used for Whitman County Farms (Albion and WSUCAF) where harvest is delayed due to its higher latitude and elevation. Table 1 indicates species and year of collection on each farm.

3) Effects of chaff or chaff and straw removal on soil organic matter and moisture content
Monthly soil samples were taken on a transect near the center of each plot over the course of the experiment. Each sample was approximately 60 cm from the previous month’s sample. A total of 290 samples were taken between May 2016 and Aug 2019 despite wet soil conditions prevented sampling in the beginning of 2017 and 2019. Each sample consisted of three intact 2.5 cm cores from 0 to 30 cm depth. Each sample was weighed wet and then dried at 40°C to determine soil moisture. The top 250 g of each dry core (approximately 0 to 20 cm depth) was sieved through a 1-mm sieve to remove un-decomposed residue using electrostatic methods. Samples from the three cores from each plot were combined for chemical analysis. Nitrogen and carbon were measured with combustion analysis. Total carbon is equal to organic carbon since this soil is free of carbonates at the surface.

The block and sample date effect were treated as random effects. The last five sample dates were used to check for treatments differences that might have developed over time. To guard against pseudo-replication due to repeated measures, the mean of all dates for each plot were also tested with a mixed model analysis of variance.

Research results and discussion:

1) Evaluation of chaff collection and chaff plus straw collection practices at harvest to reduce weed species infestation. 

Both sampling methods yielded similar results. Farm names were replaced with the closest location to protect the privacy of the participating growers.

At the Pilot Rock farm, with two studied harvests (2016 and 2018) in a crop/fallow field, no significant differences in rattail fescue (Vulpia myuros) or downy brome infestation were found by collecting or not collecting the chaff. The harvest time in this field was delayed in 2016 and 2018 for unforeseen reasons. An earlier harvest in both years could have helped to see less infestation in the plots where the chaff was collected.

At the Adams farm, with two studied harvests (2016 and 2018) in a crop/fallow field and with downy brome as the only problematic weed, infestation was reduced along the years in the plots harvested with the chaff cart but the difference with the control plots (harvested without collecting the chaff) was not significant.

At the Dixie farm, with two harvests (2017 and 2018) in a field with annual cereal cropping and with grassy weeds as the only problematic species, infestation of downy brome and Italian ryegrass (Lolium perenne spp. multiflorum) was reduced along the years using a bale direct system but the differences with the control plots (harvested without collecting the residue) were not significant. No reduction was found for the rattail fescue infestation.

At the Pendleton farm, with two cereal crop harvests (2016 and 2018) in a field with a diverse rotation, where the problematic species were tumble mustard, purple mustard, and fiddleneck, the only species that showed reduction in the plots harvested with a bale direct system was tumble mustard, although the difference with the control plots was not significant (P-value > 0.1).

At CBARC farm, with cereal annual cropping and three harvests (2016, 2017, and 2018) and where the problematic weeds were downy brome, tumble mustard (Sisymbrium altissimum), fiddleneck (Amsinckia intermedia) and prickly lettuce (Lactuca serriola), the results depended on weed species. Downy brome showed a slight reduction in infestation with the HWSC practices, but the difference was not significant. The density of tumble mustard was also reduced with the use of chaff carts and bale direct system, but the reduction was marginally significant (P-value < 0.09) only when harvesting with the bale direct system (with a reduction of 10.6% on average). Infestation differences were not found for fiddleneck or prickly lettuce.

The results found in the field are in agreement with the percentage of seed retention found in the following objective. In general, we observed a slight reduction in weed species abundance that was not statistically significant. We believe results could be improved by harvesting as soon as possible. However, this was not always possible since the crop around the experiment had to be harvested first. The soil seedbank could have also buffered the differences among treatments. Longer studies could mitigate the potential effect of the soil seedbank.  

Results on weed dispersion at the Hyslop farm showed that harvest treatments did not affect wild oat seed dispersion in 2019.

 

2) Evaluation of seed production, seed height, and seed retention of important weed species at harvest.

We studied: Feral rye (Secale cereal), downy brome (Bromus tectorum), rattail fescue (Vulpia myuros), Italian ryegrass (Lolium multiflorum), tumble mustard (Sisymbrium altissimum), purple mustard (Choriospora tenella), and common fiddleneck (Amsinckia intermedia).
Table 1

Downy brome, the most problematic weed species in small grain crops of the PNW, was collected at three farms in 2016, 2017, and five farms in 2018 (Table 1). Preliminary results showed that the percentage seed retention for a particular harvest date will depend primarily on the year conditions and secondarily on the location. While downy brome started to shed the seed by mid-June in 2016 (Figure 3a), it did not start shedding until early July in 2017 (Figure 3b). Downy brome started to shed earlier in locations with lower precipitations such as, Pilot Rock farm or Echo farm (Figure 3a, 3b, & 3c). In 2016, the population collected near Pilot Rock, OR with an average annual precipitation of 350 mm (13.7 in), started to shed by early June. However, the populations collected near Adams, OR (CBARC and Adams farm), with an average annual precipitation of 425 mm (16.7 in) started to shed by mid-June (Figure 3a). In 2017, the population collected near Echo, OR, with an average annual precipitation of 255mm (10 in), started to shed seed by early July, whereas the population collected near Adams, OR (CBARC) and the population collected near Dixie, WA, with an average annual precipitation of 480 mm (18.9 inches), started to shed beyond July 7 and July 11, respectively. In 2018, the same pattern was repeated, populations from Pilot Rock and Echo farms started to shed seed earlier than CBARC, Adams, and Dixie farms. The seed-shedding pattern responded better to an exponential model than to a linear model, indicating that the seed-shedding rate is higher during the initial harvest period.

Averaging the three years and 11 sites resulted in a 49% of seed retention (Figure 3d) by the beginning of harvest and a 27% seed retention 28 days later. These results are similar to those found for Bromus hordeacus L. (41%) at harvest time in Denmark (Glasner et al., 2019) but lower than the rates indicated for several brome species in Australia (Walsh and Powles, 2014).

The height of downy brome seeds was great enough to be collected by harvesters (Table 1). The shortest downy brome plants were found at the Pilot Rock, Echo and Dixie farms, where inter-row space was greater and crop competition may have been lower. The tallest plants were found at the CBARC and Adams farms with narrow inter-row space (15.3 cm) and denser wheat stands. HWSC might benefit from crop-weed competition by increasing weed height and making weed seeds more susceptible to collection. The suitability of downy brome for HWSC practices in the PNW will be dependent on environmental conditions and crop competition parameters (e.g. crop density, inter-row space, variety).

Figure 3

Feral rye, a problematic weed species because of the absence of herbicide options to control it in traditional wheat varieties. We sampled feral rye in one farm in 2016 (red curve in Figure 4a), in two farms in 2017 (green and blue curves in Figure 4a), and in three farms in 2018 (Figure 4b). As it happened with downy brome, this species started to shed seeds earlier in 2016 than in 2017 or 2018. The seed-shedding pattern responded better to an exponential model than to a linear model. Seed retention at the beginning of wheat harvest was similar for the three years and three locations where it was collected. Overall retention ranged from 35 to 70% with an average of 55% (Figure 4c). The Dixie Farm was the northernmost location and had the highest annual precipitation. It was the site that consistently had the highest seed retention at harvest. Contrarily, the Echo and Pilot Rock Farms were the driest location and had the lowest seed retention rates.

Feral rye height was 102 cm on average (Table 1). Its heads were located above the crop canopy and average seed retention at the beginning of harvest was pretty consistent across locations and years. This consistency was also found in Australia by Walsh and Powles (2014) despite differences in crop competition and weed density. Consequently, this species seems to have good potential for HWSC. Additional studies should be conducted to determine if the seeds collected by the combine go into the chaff fraction or remain with the grain.

Figure 4

Rattail fescue is a weed that is increasing in the PNW due to the increasing adoption of no-till systems. Rattail fescue was collected at one farm in 2016, one farm in 2017 and two farms in 2018. As with other grass weeds studied, the seed-shedding pattern of this species responded to an exponential model better than to a linear model (Figure 5). As occurred in the other species, the cool, wet conditions at the Dixie farm in 2017 may explain the higher seed retention (87%) and lower rate of seed shedding found at this location. Another factor potentially affecting the seed retention rate and the time of seed shedding at the Dixie farm could have been the use of imazamox at this location. Some surviving plants may have had their development delayed by the herbicide. The seed retention at the other sites was lower at the beginning of harvest, with an average retention rate of 23% and ranging from 14% to 29%. Rattail fescue seems to develop and shed seed earlier in drier native habitats compared to cooler and wetter conditions.

Figures 5 & Figure 6

Common Fiddleneck, a common weed in this region, was sampled at two farms in 2016 and at CBARC in 2018. It had different seed shedding patterns in the two years. In 2016, plants started to shed seeds earlier and at a much quicker pace than in 2018 (Figure 6a). By the beginning of harvest in 2016, plants had 7% on average seed retention compared to 89% in 2018. Differences could be related to differences in environmental conditions between the two seasons. The 2016 season was dry and had high temperatures that could have caused rapid seed maturation, and consequently, seed shedding. However, 2018 was a more typical year and the response of seed shedding to time was almost linear (low seed shedding rate), with a very small amount of shattering before harvest. It is also possible that seed shed in 2018 was delayed as a result of greater crop competition that delayed development of fiddleneck plants. At the two farms where this species was collected in 2016, the seed shedding pattern was similar, but it started one week earlier in the driest location (Pendleton Farm), as observed for other species in this study. The differences found between years in this study make it difficult to determine the suitability of HWSC for this species in the PNW. Plant height did not seem to be a problem, although part of the inflorescences was located at 30 cm (Table 1).

Tumble mustard, one of the most common broadleaved weeds in the semi-arid region of the PNW, was collected at two farms in 2016, 2017, and 2018 (Table 1, Figure 6b). Contrary to the grass species studied, the seed-shedding pattern of this species responded better to a linear model than to an exponential model. Tumble mustard total seed maturity was not attained until the end of June. Initial seed shedding depended on the year and site (Figure 6b). The accumulated GDD needed to start shedding seeds were similar for the Echo and Pendleton Farms in two of the years but differed for the CBARC Farm (Table 1). At CBARC, 2016 produced an earlier and steeper shedding pattern than 2018 (a year with higher precipitation). As it happened in other species, tumble mustard started to shed earlier in the drier locations and years. The average seed retention rate by July 15 was 54%. However, the range of seed retention varied from 25% to 100%. Further studies should be conducted to determine the potential efficacy of HWSC practices for this species based on the wide range of observed seed retention percentages at harvest time to.

Purple mustard, a broadleaf weed that is predominant in the experiment site located at an organic farm, was collected at that site near Pendleton, OR in 2016 and 2017 and at CBARC research center in 2018. The seed shedding pattern of this species responded to an exponential model, with a higher shedding rate early in the harvest season. The seed shedding started almost one month earlier in 2016 (early June) than in 2017 or 2018 (end of June) (Figure 6c). However, the seed shedding rate was similar throughout the seasons. Therefore, at the beginning of harvest (July 15), the percentage of seed retention was similar in 2017 and 2018, 45% and 48%, but lower (24%) in 2016 due to drier environmental conditions. Purple mustard is commonly shorter than wheat (Table 1), but the percentage of seeds below 30 cm was less than 8%. This species lodges when seed production is heavy, and the percentage of seeds not gathered by the harvester could increase drastically. Due to the relatively low percentage of seed retention at the beginning of harvest (39% on average), the quick rate of seed shedding early in the season (4% per day), and the likelihood of plant lodging, means that this species may not be a good candidate for HWSC.

 

Italian ryegrass was sampled in Washington State at three farms over two years. In both years (2017 and 2018), seed shedding started earlier at the Dixie farm than at the Albion and WSUCAF farms, which are the highest latitude and elevation farms in the study, but the rate of seed shedding was similar at all sites and years (Figure 7), especially in 2018. Seed retention at harvest was similar in both years (Figure 7c). On average, Italian ryegrass had a seed retention value of 35% at the beginning of harvest (August 1) in the populations from Whitman County, whereas retention was greater (42%) at the Dixie farm by July 15 (Figures 7a and 7b). Studies on a similar species, Lolium rigidum L., rigid ryegrass, reported greater seed retention at the beginning of harvest: 85% in Australia (Walsh and Powles, 2014), and more than 90% in Spain (Blanco-Moreno et al., 2004). It seems that Italian ryegrass is less suitable for HWSC than L. rigidum because of its earlier and quicker seed shedding pattern. However, the study in Australia was performed in wheat with a shorter life cycle. Further studies on spring wheat should be conducted to see if seed retention in this species is greater when the crop cycle is shorter.

Figure 7

The seeds of most species studied were above the regular cutting height of combines in this region (between 10 and 12 inches). Rattail fescue and purple mustard were the only two species where an important proportion of seeds might develop below the cutting height (Table 1). However, the experimental site infested with rattail fescue in 2016 (Pilot Rock Farm) was cut shorter than normal to avoid this problem.

According to these results, the timing of harvest has a critical impact on maximizing weed control with HWSC practices. The seed-shedding pattern of the weed species, cutting height of the crop, height of the seeds in the plant, year conditions and agronomic factors will play an important role in the efficacy of these practices as well. 

 

3) Effects of chaff or chaff and straw removal on soil organic matter and moisture content

Since inadequate weed pressure at the Hyslop site delayed the start of the experiment, it was decided to stop soil sampling in that location due to the shorter time available would not likely result in conclusive evidence of changes in soil carbon. Therefore, we concentrated on collecting samples from the CBARC site for as long as possible.  There were no significant differences in soil carbon or nitrogen due to chaff or chaff and straw removal treatments compared to the control or to each other (Figure 8). There were no apparent trends over the 3-yr period, or consistent differences between treatments at different seasons of the crop year.

Combined straw and chaff removal caused a statistically significant (p < 0.04) reduction in gravimetric soil moisture in the 0 to 30 cm cores (Figure 9). Relative to the control treatment (no residue removal), in the center of the plots, the average reduction in soil moisture was 3.8%. This represents an average reduction in monthly soil moisture of about 0.21 cm (0.08 inch). Removing only chaff produced a non-statistically significant relative 1% reduction.

Figures 8 & Figure 9

References:

Blanco-Moreno J, Chamorro L, Masalles RM, Recasens J, Sans FX. 2004. Spatial distribution of Lolium rigidum seedlings following seed dispersal by combine harvesters. Weed Research 44: 375–387.

Glasner C, Vieregge C, Robert J, Fenselau J, Bitarafan Z, Andreasen C. 2019. Evaluation of new harvesting methods to reduce weeds on arable fields and collect a new feedstock. Energies 12: 1688.

USDA-NASS. 1997. Usual planting and harvesting dates for U.S. field crops. Agricultural Handbook 1997: 51.

Walsh MJ, Powles SB. 2014. High Seed Retention at Maturity of Annual Weeds Infesting Crop Fields Highlights the Potential for Harvest Weed Seed Control. Weed Technology 28: 486–493.

Research conclusions:

The efficacy of harvest weed seed control (HWSC) practices in the Pacific Northwest (PNW) winter wheat cropping systems will be species dependent.

Due to the exponential response found in the seed shedding patterns of most of the studied species, the timing of harvest will have a critical impact on maximizing weed control with HWSC practices. Once the crop is mature, the sooner the harvest, the better.

In arid and semi-arid areas, where soil water accumulation is important, the removal of straw may not be a profitable practice. Growers in those areas, interested in adopting HWSC practices, should choose HWSC practices that do not remove the large parts of the residue.

Participation Summary
4 Farmers participating in research

Education

Educational approach:

The educational and outreach plan for producers and Ag professionals in the immediate area covered by this project will be conducted through producer meetings in different counties (e.g. Walla-Walla, Columbia, and/or Whitman in WA, and Umatilla, Union, and/or Sherman in OR), field days (Pendleton (we will show the experiment), Moro, and Pullman), local newspaper (Agritimes, and East Oregonian), and radio stations (KFAE 89.1 owed by WSU).
To extend the knowledge to producers and Ag professional outside of the immediate area, we plan to upload videos of the new practices to the websites of collaborators that show how the practices were implemented at our participating and research farms. Furthermore, we will write extension articles and fact sheets published by WSU or OSU, talk about the project and its results in seminars (Cereal Seminar in Walla-Walla, Farm Fair in Hermiston), and participate in annual meetings of scientific societies in the state (e.g. Oregon Society of Weed Science).
Our outreach plan is to extend the new knowledge in the western region among producers and Ag professionals through participation in regional and national conferences (e.g. Western Society of Weed Science, Pacific Northwest Direct Seed, and Weed Science Society of America). Particularly, we will organize a symposium session at the Pacific Northwest Direct Seed Annual meeting in winter of 2020 to extend the new knowledge and practices generated in this project.

Educational & Outreach Activities

6 Consultations
5 Curricula, factsheets or educational tools
1 Journal articles
1 Published press articles, newsletters
65 Webinars / talks / presentations
4 Workshop field days

Participation Summary:

1883 Farmers
1016 Ag professionals participated
Education/outreach description:

Some of the extension activities that the PI and Co-PIs have conducted in relation to the project are described below:

 

Presentations in 2019 and early 2020:

Dr. Judit Barroso gave the following presentations where the project results were explained:

  • Harvest Weed Seed Control in Wheat Production Systems of the PNW. WSSA/WSWS Annual Meeting. Lahaina, Hawaii. March 2-5, 2020. (≈ 200 attendees)
  • Harvest Weed Seed Control. IPM Workshop Focused on Managing Weeds in the 21st Bozeman, MT. June 18, 2019. (≈ 40 attendees). Invited.
  • Harvest Weed Seed Control and Integrated Weed Management. Sherman Station Field Day. Moro, OR. June, 12, 2019. (≈ 95 attendees).
  • Harvest Weed Seed Control and Integrated Weed Management. Pendleton Station Field Day. Adams, OR. June, 11, 2019. (≈ 100 attendees).
  • Harvest Weed Seed Control and Integrated Weed Management. Hermiston Irrigated Cereal Field Day. Hermiston, OR. June, 10, 2019. (≈ 25 attendees). Invited.

Dr. Judit Barroso included discussion on HWSC in the following presentation:

  • Herbicide Resistance in the Pacific Northwest. Pacific Northwest Direct Seed Association (PNDSA) Annual Meeting - Cropping Systems Conference. Three Rivers Convention Center, Kennewick, WA. January 8, 2020. (≈ 60 attendees). Invited.
  • Research Update of Weed Program at CBARC. OSWS Annual Meeting. Hood River, OR. October 24, 2019 (≈ 170 attendees).

Drew Lyon discussed harvest weed seed control in several presentations given in 2019:

  • January 15th – Walla Walla Cereal Seminar, Walla Walla, WA
  • January 24th – Columbia County Noxious Weed Board Annual Meeting, Dayton, WA
  • January 29th – WSU Pesticide Education Program, Yakima, WA
  • January 30th – Wilbur-Ellis Northern Palouse Annual Grower Meeting, Fairfield, WA
  • February 12th – WSU Pesticide Education Program, Wenatchee, WA
  • February 15th – WSU Pesticide Education Program, Spokane, WA
  • February 18th – WSU Pesticide Education Program, Kennewick, WA
  • February 25th – WSU Pesticide Education Program, Pullman, WA
  • June 18th – Eastern Klickitat County No-till Workshop, Bickleton, WA
  • June 19th – WSU Weed Science Tour, Pullman, WA
  • November 26th – Spokane County Crop Improvement Association Annual Meeting, Airway Heights, WA
  • December 3rd – WSU Stevens County Extension 2019 Pesticide License Re-certification Event, Colville, WA

 

Presentations in 2018:

Dr. Judit Barroso gave the following presentations where the project was explained:

  • Weed Control at Harvest. Oregon Society of Weed Science (OSWS) Annual Meeting. Hood River, OR. October 24, 2018 (≈ 170 attendees among growers, industry field reps, students and crop consultants).
  • Seed Retention of Major Weed Species at Harvest in the PNW. Western Society of Weed Science (WSWS) Annual Meeting. Garden Grove, CA. March 14th, 2018. (≈ 50 attendees among industry field reps, students, and peers).
  • Impacts of Chaff Collection and Bale Direct Systems to Improve Weed Control. CBARC seminars series. CBARC, Adams, OR. March 6th, 2018. (38 attendees, mostly growers and some peers).

Dr. Judit Barroso included discussion of HWSC in several extension presentations and research updates:

  • Research Update on the Weed Program at CBARC. Oregon Wheat League Gilliam County Meeting. Grower’s house, Condon, OR. October 24th, 2018. (20 attendees).
  • Program Update on Harvest Weed Seed Control and Herbicide Resistance to Group 2 Herbicides in Downy Brome. Post-Harvest Dryland Extension Meeting. Blue Mountain Community College, Pendleton, OR. September 6th, 2018. (≈ 25 attendees).
  • Weed Research in Cropping Systems of Pacific Northwest. Institute of Agrarian Science of the Spanish National Research Council (ICA-CSIC). Madrid, Spain. June 22nd, 2018. (15 attendees).
  • OSU-CBARC Weed Science Program Update. Annual Union-Baker Grower’s Winter Meeting. La Grande, OR. January 31st, 2018. (40 attendees). Invited.

Drew Lyon discussed the topic of harvest weed control in a presentation that he gave several times on Management of Italian Ryegrass:

  • Italian Ryegrass Management. 12/14/2018. Asotin County Pesticide Credits meeting in Clarkston, WA. (80 growers and industry field reps).
  • Weed Tales From the US Pacific Northwest. 11/13/2018. University of Queensland, Gatton, Queensland Australia. (25 students and peers).
  • Weed Tales from the US Pacific Northwest. 11/12/2018. Queensland Department of Agriculture and Fisheries, Toowoomba, Queensland, Australia. (25 growers and peers).
  • Weed Tales from the US Pacific Northwest. 10/30/2018. Charles Sturt University, Wagga Wagga, NSW Australia. (35 students and peers).
  • Weed Tales from the US Pacific Northwest. 10/26/2018. University of Sydney I.A. Watson Grains Research Centre, Narrabri, NSW Australia. (30 growers and peers).
  • Cross-Continental Kissing Cousins: Is Australian Management of Annual Ryegrass Transferable to Italian Ryegrass Management in the US Pacific Northwest?. 10/23/2018. University of Sydney, Sydney, Australia. (40 students and peers).

Dr. Andy Hulting mentioned this project and the concept of harvest weed seed control in the following extension presentations:

  • Fall Weed Management Recommendations for Grass Seed Crops. 9/22/18. Albany, OR, OSU Extension/OR Wheat Growers League Valley Wheat Production Meetings. (85 growers and industry field reps).
  • Fall Weed Management Recommendations for Grass Seed Crops. 9/22/18. West Salem, OR, OSU Extension/OR Wheat Growers League Valley Wheat Production Meetings. (75 growers and industry field reps).
  • Fall Weed Management Recommendations for Grass Seed Crops. 9/23/18. Forest Grove, OR, OSU Extension/OR Wheat Growers League Valley Wheat Production Meetings. (75 growers and industry field reps).
  • Group 2 Herbicide Resistance in Grass Weeds in Wheat Production. 6/13/18. Hermiston, OR, Hermiston Ag Research and Extension Center Irrigated Cereal Field Day. (20 growers and agribusiness professionals).
  • Weed Management Options in Grass Grown for Seed. 2/21/18.  Paul, OR, Marion Ag Service Growers’ Meeting. (25 growers).

 

Presentations in 2017:

Dr. Judit Barroso gave the following presentations where the project was explained:

  • November 30th, 2017 – Hermiston Farm Fair Seminars & Tradeshow, Hermiston, OR. Judit Barroso gave a seminar titled ‘Integrated Weed Management: Harvest Weed Seed Control’ where she explained the preliminary results of this project. (90 people in attendance).
  • October 27, 2017 – Annual meeting of the Spanish Society of Weed Science, Pamplona, Spain. Judit Barroso gave a seminar titled ‘Weed Seed Control at Harvest: Preliminary Results’ where she explained the harvest practices included in the project and their preliminary results (150 people in attendance).

Judit Barroso included discussion of HWSC in several extension presentations and research updates:

  • January 11th, 2017. Help With Herbicide-Resistant Weeds. PNDSA Cropping Systems Conference. Kennewick, WA (40 growers in attendance).
  • February 21st, 2017. Why Integrated Weed Management? Malheur County Pest Management Short Course. Ontario, OR (125 growers, industry field reps and crop consultants in attendance).
  • April 5th, 2017. Getting to Know You. Crop and Soil Science Department Spring Conclave. Corvallis, OR (28 Scientists and instructors in attendance).
  • December 6th 2017. Is Volunteer Wheat a Weed in Wheat Productions? CBARC seminar series. Adams, OR (20 growers, technical personnel, and scientists in attendance).

Drew Lyon discussed the topic of harvest weed control in a presentation that he gave several times on Herbicide Resistance and Integrated Weed Management:

  • January 18, 2017. Simplot Growers Symposium. Bickleton, WA (17 people in attendance).
  • January 25, 2017. Walla Walla County Conservation District Annual Meeting. Walla Walla, WA (48 people in attendance).
  • February 1, 2017. Palouse-Rock Conservation District Annual Meeting. St. John, WA (75 people in attendance).
  • February 1, 2017. Washington Department of Ecology Burn Task Force Meeting. Spokane, WA (18 people in attendance).
  • February 21, 2017. Western Klickitat County Conservation District Annual Meeting. Goldendale, WA (38 people in attendance).
  • February 23, 2017. Ag Ventures & Davenport Union Annual Grower Meeting. Davenport, WA (85 people in attendance).
  • December 5, 2017. Wheat U. Spokane, WA (210 people in attendance).

Andy Hulting mentioned this project and the concept of harvest weed seed control in the following extension presentations:

  • January 10, 2017. Weed Management Recommendations for Grass Seed Crops and Cereals. Wheat Growers League Valley Wheat Production Meetings. Albany, OR, OSU Extension/OR (85 growers and industry field reps).
  • January 10, 2017. Weed Management Recommendations for Grass Seed Crops and Cereals. Wheat Growers League Valley Wheat Production Meetings. West Salem, OR, OSU Extension/OR (100 growers and industry field reps).
  • January 24, 2017. Management of Herbicide Resistant Weeds Southern Oregon Pesticide Recertification School. Central Point, OR (90 growers and applicators).
  • February 2, 2017. Managing Weeds in Clover Grown for Seed. Clover Growers Annual Meeting. Wilsonville, OR (150 growers).

 

Presentations in 2016:

Dr. Judit Barroso gave the following presentations where the project was explained:

  • April 6, 2016 – CBARC Seminar Series, Pendleton, OR. Judit Barroso gave a seminar titled ‘Impacts of chaff collection or chaff plus straw collection at harvest to improve weed control’ to talk about the project with growers in the region (29 people in attendance).
  • June 27-29, 2016. Brand Experiment Station Directors’ Summer Meeting, CBARC, OR. Judit Barroso introduced the project to several OSU directors of experiment stations, one university dean and, several summer students (15 people in attendance).
  • September 7-8, 2016. PNW Weed Workers Gathering. Corvallis, OR. Judit Barroso presented the project to other weed scientists not directly involved and to several graduate students (36 people in attendance).
  • October 11, 2016. Invited Lecture in AGRI299 course: “Weed Science Program at CBARC”, La Grande, OR (EOU & OSU). Judit Barroso discussed the project with the students of the AGRI299 course (28 students in attendance).

Drew Lyon included discussion of Harvest Weed Seed Control in several extension presentations on herbicide resistance and Integrated Weed Management:

  • November 1, 2016. Walla Walla County Wheat Growers Association Annual Meeting in Walla Walla, WA (21 people in attendance).
  • November 22, 2016. Spokane County Crop Improvement Association Annual Meeting in Spokane, WA (52 people in attendance).
  • December 16, 2016. Integrated Pest Management Update in Clarkston, WA (42 people in attendance).

Andy Hulting mentioned this project and the concept of harvest weed seed control in the following extension presentations:

  • September 22, 2016. Fall Weed Management Recommendations for Grass Seed Crops and Cereals. Wheat Growers League Valley Wheat Production Meetings. Albany, OR, OSU Extension/OR (85 growers and industry field reps).
  • September 22, 2016. Fall Weed Management Recommendations for Grass Seed Crops and Cereals. Wheat Growers League Valley Wheat Production Meetings. West Salem, OR, OSU Extension/OR (75 growers and industry field reps).
  • September 23, 2016. Fall Weed Management Recommendations for Grass Seed Crops and Cereals. Wheat Growers League Valley Wheat Production Meetings. Forest Grove, OR, OSU Extension/OR (75 growers and industry field reps).
  • December 13, 2016. Updates on OSU Weed Management Projects in Seed Crops. 2016 Oregon Seed League Meeting. Salem, OR (150 growers and agribusiness professionals).

 

Publications where information about this project has been included:

San Martín C., Lyon D.J., Thorne M., Barroso J.  (2020). Weed seed retention at wheat harvest in the Pacific Northwest. Weed Science (Submitted April 15, 2020).

Barroso J., San Martín C., Gourlie J.A., Wuest S.W., Thorne M., Roerig K., and Hulting A. 2020. Harvest Weed Seed Control in Wheat Production Systems of the PNW. Proceedings of the Weed Science Society of America (WSSA)/Western Society of Weed Science (WSWS) Annual Meeting. Lahaina, Hawaii. March, 2020.

Lyon D.J., Walsh M.J., Barroso J., Campbell J., and Hulting A. 2019. Harvest Weed Seed Control: Applications for PNW Wheat Production Systems. PNW 730, 12 pages. https://pubs.extension.wsu.edu/harvest-weed-seed-control-applications-for-pnw-wheat-production-systems.

Barroso J., San Martin C., Thorne M., and Lyon D. 2018. Seed retention of major weed species at harvest in the PNW. Proceedings of western society of weed science (WSWS) Annual Meeting Garden Grove, CA. Abstract. Pp. 69.

Barroso J. and San Martín C. 2018. Seed Retention of Major Grass Weed Species at Harvest in the PNW. Field Day Abstracts. June 2018, pp. 70.

Barroso J., San Martin C., Gourlie J. 2017. Weed Seed Control at Harvest: Preliminary Results. Proceedings of the SEMh. October 2017. Pamplona, Spain, pp: 369-373.

Esser A., Barroso J., and Lyon D.S. 2017. Help with Herbicide-Resistant Weeds. Proceedings of PNDSA Cropping Systems Conference. January, 2017. Kennewick, WA. Abstract.

 

In addition to presentations and publications, we are being consulted by a few growers about concepts and equipment needs to implement the harvest weed seed control practices that we are studying. Mostly, the growers that are asking us are the ones having problems with herbicide resistant weeds and particularly, resistant Italian ryegrass.

 

Learning Outcomes

45 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key areas taught:
  • Different practices to control weed seeds at harvest

Project Outcomes

2 Farmers intend/plan to change their practice(s)
2 New working collaborations
Project outcomes:

Results are showing that collection of chaff and/or collection of chaff plus straw could be useful to reduce weed pressure depending on weed species present and if the crop harvest is not delayed once the crop is mature.

The project provides information about a new tool to include in integrated weed control strategies that will help reduce weed infestations (particularly herbicide resistant weeds) and herbicide pressure.

The project results can help growers make informed decisions on the initial investment required for some of the HWSC practices base on their problematic species and the maximum percentage of weed control reported.  

The project is helping sustainability by providing science-based information to control weeds with HWSC in the PNW. HWSC practices is proven profitable for Australian farmers to control rigid ryegrass but profitability in the PNW is not as straightforward. It will depend on several factors that the US growers should consider before adoption.

The results from this project also indicates that in arid and semi-arid areas, where soil water accumulation is important, the removal of straw may not be a profitable practice. Growers in those areas, interested in adopting HWSC practices, should choose HWSC practices that do not remove the large parts of the residue.

Success stories:

One grower from Walla-Walla County, WA mentioned in one of our presentations that he had observed weed reduction since he was using a bale direct system.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.