Thomas G. Chastain

Here’s a new article from our seed production research and extension team on irrigation and trinexapac-ethyl PGR effects on seed yield and yield components in red clover seed crops.  Field trials were conducted in the Willamette Valley over a 3-year period at OSU’s Hyslop Farm.  Trinexapac-ethyl is marketed around the world as Palisade, Moddus, and several generic products for lodging control and seed yield enhancement in cool-season grass seed crops and legume seed crops.

Floret bleaching in red clover, a common effect of TE PGR application (TG Chastain photo)
Floret bleaching in red clover, a common effect of trinexapac-ethyl PGR application (TG Chastain photo)

This article appears in the current issue of Agronomy Journal and can be found at the link below:

Anderson, N.P., T.G. Chastain, and C.J. Garbacik. 2016. Irrigation and trinexapac-ethyl effects on seed yield in first- and second-year red clover stands. Agron. J. 108:1116-1123.

Key findings of the article:

  • Irrigation strategically-timed to coincide with peak flowering consistently increased seed yield in red clover regardless of stand age.
  • Trinexapac-ethyl PGR increased seed yield in second-year red clover stands but not in first-year stands.
  • Irrigation and trinexapac-ethyl independently increase the yield of red clover seed crops but there were no interactions between the two.

Thomas G. Chastain

The combination of very dry and warm weather in spring and early summer 2015 is a cause for concern for growers of grass and forage legume seed crops in the Willamette Valley. Moreover, these conditions have accelerated the timing of the harvest of seed crops in the region. One question that has arisen is how will these conditions affect seed yield?

Seed Field
Aerial view of windrow-harvested seed field in the Willamette Valley.
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Here’s a new article from our seed production research and extension team on trinexapac-ethyl plant growth regulator (PGR) and its effects on seed yield and yield components in red clover (Trifolium pratense L.) seed crops.  The field trials were conducted in the Canterbury region of New Zealand and in seed fields in the Willamette Valley.

Red clover leaf (TG Chastain photo)
Red clover leaf (TG Chastain photo)

This article will appear in an upcoming issue of Agronomy Journal and is a part of our series on PGR tools for use in legume and grass seed production.  The product is marketed around the world as Palisade, Moddus, and several generic products for lodging control and seed yield enhancement in cool-season grass seed crops and legume seed crops.

Key findings of the article:

  • Trinexapac-ethyl was responsible for seed yield increases in red clover ranging from 9 to 15% in New Zealand and Oregon’s Willamette Valley.
  • One contributing factor for the increased seed yield with trinexapac-ethyl was that the PGR increased the number of heads formed in the red clover crop.  Moreover, the PGR reduced the height of the crop canopy and increased penetration of light into the canopy, possibly leading to the increased head production.
  • Timing of trinexapac-ethyl applications to coincide with early stem elongation gave the best seed yields although split applications at stem elongation and bud emergence produced yield increases in Oregon.
  • Seed weight was generally inversely related to yield; trinexapac-ethyl treatments that produced the highest yield also had the lowest seed weight.

The article can be found at the link below:

Anderson, N.P., D.P. Monks, T.G. Chastain, M.P. Rolston, C.J. Garbacik, Chun-hui Ma, and C.W. Bell. 2015. Trinexapac-ethyl effects on red clover seed crops in diverse production environments. Agron. J. 107:951-956.

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Thomas G. Chastain

Dry conditions are normal for the Willamette Valley in July and August.  This is an important period for flowering and seed development in red clover seed crops.  While much of the region’s red clover seed crop is not irrigated, would the crop benefit from additional water during this dry period?  That is one of the questions that the seed production research and extension team has addressed.

Red clover irrigation trials at Hyslop Farm (TG Chastain photo)
Red clover irrigation trials at Hyslop Farm (TG Chastain photo)

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A special local needs label has been recently approved for use of Palisade EC plant growth regulator for red clover and crimson clover seed crops in Oregon.  This is timely because the window for application of the product on these crops is near.

For more information, here is a copy of the SLN label:

Palisade EC for Red Clover and Crimson Clover Grown for Seed

As always, follow the label when applying this or any other product. Mention of this product does not constitute an endorsement by Oregon State University.

Thomas G. Chastain

Several forage legume seed crops continue to be a vital part of seed production enterprises in the Willamette Valley.  These include red clover, crimson clover, and white clover.  Other seed crops that have been produced in the valley include ladino clover, arrowleaf clover, subterranean clover, hairy vetch, and common vetch.

Figure 1. Crimson clover in flower. (T.G. Chastain photo)

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