Thomas G. Chastain

Grass seed crop acreages in Oregon’s Willamette Valley have varied over time.  One interesting aspect of the rise and fall of grass seed crop acreages in the region is their relationship with wheat acreages in the Willamette Valley.  A rise in grass seed crop acreage is mirrored by a simultaneous fall in wheat acreage and vice versa, and these trends are evident in the graphic below.

Grass seed and wheat trends Continue reading

A new publicPicture1ation on nutrient management in perennial ryegrass seed crops has just been released by OSU’s grass seed production research and extension team.  The publication (EM 9086) is a product of many years of  field work in grass seed crops by the members of the research and extension team.  The nutrient management guide covers the impacts of application of nutrients on seed yield, seed yield components, crop growth and development, plant growth regulator use, pests, and others.  Extensive use of tables, figures, and appendices supplement this comprehensive work on perennial ryegrass nutrient management.

The publication can be accessed at the link below:

Perennial Ryegrass Grown for Seed (Western Oregon) EM 9086

Here’s  a new article from our research group on trinexapac-ethyl plant growth regulator (PGR) effects in perennial ryegrass seed crops that will be published in Field Crops Research.  This PGR is marketed as Palisade, Moddus, and several generic products.  The trials were conducted from 1998 to 2012 at OSU’s Hyslop Farm.

Figure 1.  Lodging in ryegrass.
Figure 1. Lodging in ryegrass.

The study reports several important findings:

  • Application of trinexapac-ethyl PGR reduced stem length and controlled lodging in perennial ryegrass across nine diverse lodging environments in the Willamette Valley of Oregon.
  • Trinexapac-ethyl PGR consistently increased seed yield and harvest index in perennial ryegrass regardless of the severity of lodging.
  • Timing trinexapac-ethyl applications between BBCH stages 32 and 51 produced the best seed yield results.
  • Seed yield increases resulting from trinexapac-ethyl application were attributable to a greater number of seeds spikelet-1 (seed number) and improvements in seed set.


Click on the citation below to go to the article:

Chastain, T.G., W.C. Young III, T.B. Silberstein, and C.J. Garbacik.  2014.  Performance of trinexapac-ethyl on seed yield of Lolium perenne in diverse lodging environments.  Field Crops Research 157:65-70.


Thomas G. Chastain

The late summer and early fall period has long been thought to be critical for regrowth of the perennial ryegrass and tall fescue seed crops after harvest and for the following year’s seed yield.  Extremely dry conditions during this period in the Willamette Valley can reduce stands and crop regrowth in both seed crops.  There is good evidence from our research that irrigation improves the appearance of the stand (number of tillers and stand cover) going into the winter.  But what about the impact of fall irrigation on seed yield in perennial ryegrass and tall fescue?

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Thomas G. Chastain

The stubble and straw remaining in grass seed fields after harvesting seed is known as residue.  Post-harvest residue burning has been justified on the basis of pest control and stimulation of seed yield.  Public concern over air quality and the potential for adverse health impacts on the region’s residents has necessitated the identification of alternative residue management practices.  Oregon legislation (SB 528) has, in effect, ended the practice of field burning in the western part of the state for most species except for the fine fescues.

Smoke plume from open-field burning in Oregon’s Willamette Valley. (T.G. Chastain photo)

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Crop fields are generally not uniform and the harvested yield can vary across the field.  Perennial ryegrass seed production fields are also not very uniform but some farmers use yield monitors on their combines to estimate seed yield and the spatial variability in seed yield across their fields.

This variability can be mapped for the fields where yield monitors are used and these maps can serve as the basis for making crop management decisions.  But the reliability of these yield monitor-based estimates was not known for perennial ryegrass seed crops.

A recent paper by co-authored by extension agronomist in seed production Bill Young and others at OSU finds that there is considerable variability in seed yield in an otherwise uniform perennial ryegrass seed field and that a yield monitor can reliably capture this variability in seed yield.

Click on the link below to go to the article:

Reliability of Yield Mapping System for Estimating Perennial Ryegrass Seed Yield