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fewer viable weed seeds

Fate of weed seeds after impact mill processing in midwestern and mid-Atlantic United States

Harvest weed seed control (HWSC) technology, such as impact mills that destroy weed seeds in seed-bearing chaff material during grain crop harvest, has been highly effective in Australian cropping systems. However, the impact mill has never been tested in soybeans [Glycine max (L.) Merr.] and weeds common to soybean production systems in the midwestern and mid-Atlantic United States. We conducted stationary testing of Harrington Seed Destructor (HSD) impact mill and winter burial studies during 2015 to 2016 and 2017 to 2018 to determine (1) the efficacy of the impact mill to target weed seeds of seven common weeds in midwestern and five in the mid-Atlantic United States, and (2) the fate of impact mill-processed weed seeds after winter burial. The impact mill was highly effective in destroying seeds of all the species tested, with 93.5% to 99.8% weed seed destruction in 2015 and 85.6% to 100% in 2017. The weak relationships (positive or negative) between seed size and seed destruction by impact mill and the high percentage of weed seed destruction by impact mill across all seed sizes indicate that the biological or practical effect of seed size is limited. The impact mill-processed weed seeds that retained at least 50% of their original size, labeled as potentially viable seed (PVS), were buried for 90 d overwinter to determine the fate of weed seeds after winter burial. At 90 d after burial, the impact mill-processed PVS were significantly less viable than unprocessed control seeds, indicating that impact mill processing physically damaged the PVS and promoted seed mortality overwinter. A very small fraction (<0.4%) of the total weed seed processed by the impact mill remained viable after winter burial. The results presented here demonstrate that the impact mill is highly effective in increasing seed mortality and could potentially be used as an HWSC tactic for weed management in this region.

Keywords

  • Harrington seed destructor (HSD)
  • harvest weed seed control (HWSC)
  • herbicide resistance
  • seed viability
  • weed seed decay
  • weed seed kill
  • weed seed mortality

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science

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In: Weed Science , Vol. 68, No. 1, 2019, p. 92-97.

Research output : Contribution to journal › Article › peer-review

T1 – Fate of weed seeds after impact mill processing in midwestern and mid-Atlantic United States

AU – Shergill, Lovreet S.

AU – Bejleri, Kreshnik

AU – Mirsky, Steven B.

N1 – Funding Information: The authors acknowledge area-wide financial support from USDA-ARS (project no. 8042-22000-166-20-S). We also express our gratitude to Victoria Ackroyd (Research Scientist, Sustainable Agricultural Systems Laboratory, USDA-ARS) for reviewing the early draft of this paper. We also acknowledge the technical assistance provided by Allen Burke, Ethan Sweep, Cara Peterson, Jennifer Showalter, Nicholas Hausman, and several undergraduate and graduate students. Funding Information: The authors acknowledge area-wide financial support from USDA-ARS (project no. 8042-22000-166-20-S). We also express our gratitude to Victoria Ackroyd (Research Scientist, Sustainable Agricultural Systems Laboratory, USDA-ARS) for reviewing the early draft of this paper. We also acknowledge the technical assistance provided by Allen Burke, Ethan Sweep, Cara Peterson, Jennifer Showalter, Nicholas Hausman, and several undergraduate and graduate students.

N2 – Harvest weed seed control (HWSC) technology, such as impact mills that destroy weed seeds in seed-bearing chaff material during grain crop harvest, has been highly effective in Australian cropping systems. However, the impact mill has never been tested in soybeans [Glycine max (L.) Merr.] and weeds common to soybean production systems in the midwestern and mid-Atlantic United States. We conducted stationary testing of Harrington Seed Destructor (HSD) impact mill and winter burial studies during 2015 to 2016 and 2017 to 2018 to determine (1) the efficacy of the impact mill to target weed seeds of seven common weeds in midwestern and five in the mid-Atlantic United States, and (2) the fate of impact mill-processed weed seeds after winter burial. The impact mill was highly effective in destroying seeds of all the species tested, with 93.5% to 99.8% weed seed destruction in 2015 and 85.6% to 100% in 2017. The weak relationships (positive or negative) between seed size and seed destruction by impact mill and the high percentage of weed seed destruction by impact mill across all seed sizes indicate that the biological or practical effect of seed size is limited. The impact mill-processed weed seeds that retained at least 50% of their original size, labeled as potentially viable seed (PVS), were buried for 90 d overwinter to determine the fate of weed seeds after winter burial. At 90 d after burial, the impact mill-processed PVS were significantly less viable than unprocessed control seeds, indicating that impact mill processing physically damaged the PVS and promoted seed mortality overwinter. A very small fraction (<0.4%) of the total weed seed processed by the impact mill remained viable after winter burial. The results presented here demonstrate that the impact mill is highly effective in increasing seed mortality and could potentially be used as an HWSC tactic for weed management in this region.

AB – Harvest weed seed control (HWSC) technology, such as impact mills that destroy weed seeds in seed-bearing chaff material during grain crop harvest, has been highly effective in Australian cropping systems. However, the impact mill has never been tested in soybeans [Glycine max (L.) Merr.] and weeds common to soybean production systems in the midwestern and mid-Atlantic United States. We conducted stationary testing of Harrington Seed Destructor (HSD) impact mill and winter burial studies during 2015 to 2016 and 2017 to 2018 to determine (1) the efficacy of the impact mill to target weed seeds of seven common weeds in midwestern and five in the mid-Atlantic United States, and (2) the fate of impact mill-processed weed seeds after winter burial. The impact mill was highly effective in destroying seeds of all the species tested, with 93.5% to 99.8% weed seed destruction in 2015 and 85.6% to 100% in 2017. The weak relationships (positive or negative) between seed size and seed destruction by impact mill and the high percentage of weed seed destruction by impact mill across all seed sizes indicate that the biological or practical effect of seed size is limited. The impact mill-processed weed seeds that retained at least 50% of their original size, labeled as potentially viable seed (PVS), were buried for 90 d overwinter to determine the fate of weed seeds after winter burial. At 90 d after burial, the impact mill-processed PVS were significantly less viable than unprocessed control seeds, indicating that impact mill processing physically damaged the PVS and promoted seed mortality overwinter. A very small fraction (<0.4%) of the total weed seed processed by the impact mill remained viable after winter burial. The results presented here demonstrate that the impact mill is highly effective in increasing seed mortality and could potentially be used as an HWSC tactic for weed management in this region.

Ohio: With Marestail, It’s All About Winning The Long Game – The Seed Bank

For the second year in a row, we are scrounging to find enough marestail at the OARDC Western Ag Station to conduct the research we had planned on this weed. After years of having plenty of marestail, we have had to look around for off-site fields where there is still a high enough population.

Which, since we are scientists after all, or at least make our best attempts, left us thinking about reasons for the lack of marestail, and our overall marestail situation, and seedbanks.

While the short game in weed management is about getting good enough control to prevent weeds from being a yield-limiting factor and interfering with harvest, the long game is about preventing seed production and managing the soil seedbank. One of the characteristics shared by marestail, giant ragweed, and the nasty pigweeds, waterhemp and Palmer amaranth, is a rapid decline in seed viability in the soil within the first year, and an overall decline to 5% or less viable seed within 3 to 4 years.

Another characteristic of marestail and pigweed seed is a relative lack of dormancy, which results in the potential for an almost immediate increase in population the year following a year of substantial escapes and seed production. How big that increase is depends upon how many plants go to seed and how many seeds are produced per plant, with the potential of up to about 200,000 seeds per marestail plant and one million per waterhemp or Palmer amaranth plant.

The net result of these two characteristics, though, is that these weeds can ramp up population fast following a year of poor control, but populations can also decline rapidly with good control that prevents seed.

Marestail has probably the most variable emergence pattern of any annual weed we study, which is the reason that control requires a comprehensive management program. Trying to plan herbicide use based on a guess about whether the major emergence will be in fall, or spring, or early summer won’t work. A management program should be planned on the assumption that all of these can occur.

We assume that environmental conditions over the year determine the patterns of marestail emergence, and that it’s possible a certain set of conditions have just greatly reduced emergence at our research farm. Not sure we buy this completely though – two years in a row?

Thinking about the broader picture, one could conclude that we are just obtaining better control of marestail and reducing seed production due to adoption of more effective management strategies and the increased use of LibertyLink and other technologies. This is certainly occurring at our research farm, and our end of season survey of weeds in soybean fields shows about a 50% reduction in marestail over the past 6 years.

Marestail seed is moved by wind, and based on the above thoughts, one could conclude that we just have fewer seed floating around in the Ohio airspace. This means less overall potential for sustained high marestail populations or reintroduction of marestail into fields where effective management has driven down the population. A good thing.

Before we collectively pat ourself on the back for this, we should state that there are growers and areas where marestail is still not well controlled, for one reason or another. And the fact that there is plenty of marestaail going to seed in natural areas, parks, right of ways, etc means there is still a source of new infestations. And having more effective technologies available does not mean we can go back to an oversimplified herbicide program that overuses certain foliar herbicides, such as glufosinate, dicamba, and 2,4-D.

The fact that almost all marestail populations are resistant to the two herbicide sites of action that were effective in POST applications to begin with, glyphosate and ALS inhibitors, means that we should assume the potential exists to develop resistance to glufosinate, dicamba, and 2,4-D.