Tag Archives: Grass Seed Crops

Rain during grass seed harvest

Posted on by

Thomas G. Chastain

The Willamette Valley does not expect much rain during harvest of grass seed crops.  The production practices for grass seed crops in the region have evolved to take advantage of the dry conditions that are prevalent during harvest.  But when rain falls during the harvest season, questions arise regarding the effects of this late precipitation on seed yield and quality of grass seed crops.

Seed Field
Aerial view of windrow harvested Willamette Valley grass seed field.

For grass seed crops that are at the pre-harvest stage during precipitation events, rain is usually not a problem and even after the crop is cut, the worst consequence is that the crop will take more time to dry down to reach combine seed moisture in the swath.  However, if the delay in drying is too long, grass blades can grow up and through the swath making combining operations difficult.  Tall fescue seems to be particularly problematic with regard to post-swathing leaf growth.  When grass blades grow back up through the swath, some farmers recut the swath to facilitate combine harvesting but some seed losses can be expected in this operation due to shattering.  If the crop is swathed onto wet soil and remains there for an extended period, there can be some losses in yield and quality as a result of the action of fungi and other pests.

The potential for damage to seed crop yield and quality is dependent on the intensity and duration of rainfall.  Excessive rain after the grass seed crop is swathed can be a problem, especially in July and early August (for later maturing crops).  First, the action of the falling rain in some circumstances can be sufficient to cause shatter losses of seed in the swath.  Secondly, if rain is persistent and is accompanied by high humidity, then seed can sprout, thereby reducing the quality and marketability of the seed.  These late season high rainfall events are not very common and that is why the seed industry has few artificial drying facilities in the region.  Pre-harvest sprouting of grass seed was observed in the Willamette Valley in 1983 and again in 1993.  Light rainfall after swathing of the crop is not generally a problem.

Seed moisture and harvest timing in grass seed crops

Posted on by

Thomas G. Chastain

In order to maximize harvest efficiency and seed yield, using the appropriate timing for harvest is essential. Seed moisture content is the most reliable indicator of seed maturity and harvest timing in grass seed crops.

Since pollination and seed maturation are not uniform processes in grass seed crops, a range of seed maturity can be found in a single field. Harvesting within the correct range of seed moisture contents will maximize seed yield and minimize losses of seed during harvest. Seed moisture content is also an important factor in the storage of harvested seed. High seed moisture content reduces longevity of seed in storage and reduces seed quality.

To optimize the timing to swath grass seed crops and to maximize the quantity of seed harvested, seed growers must balance cutting late-maturing seeds too early with cutting early-maturing seeds too late. Cutting too early at high seed moisture content shortens the seed fill period leading to immature seed and reduced seed size or weight. Cutting too late at low seed moisture content can reduce yield as a result of seed shattering losses.

The table below shows the seed moisture content range recommended for swathing of grass seed crops:

Crop

Recommended seed moisture for swathing (%)

Moisture loss per day (%)

Annual ryegrass

43-48

2.0-3.0

Orchardgrass

42-46

1.0

Tall Fescue (forage)

40-43

2.5-3.0

Tall Fescue (turf)

35-45

2.5-3.0

Perennial ryegrass

35-43

3.0

Chewings fescue

30

5.0

Creeping red fescue

25-35

4.0

Kentucky bluegrass

24-28

3.0-4.0

Illustrated instructions on how to conduct a seed moisture test in grass seed crops and guidelines for seed moisture contents for best harvest efficiency can be found in OSU’s publication EM 9012. Here’s a link to the publication:

Using Seed Moisture as a Harvest Management Tool

A video showing step by step instructions on collecting seed and methods to test moisture content of seed is linked below:

Seed moisture and harvest video

Spring water use and irrigation in perennial ryegrass and tall fescue

Posted on by

Thomas G. Chastain

Field trials conducted in the Willamette Valley showed that crop water use from April 1st through seed harvest in perennial ryegrass seed crops was 10.5 inches on a medium textured soil (silt loam).  Crop water use in tall fescue during the same period was 10.1 inches on the same soil type.  A perennial ryegrass or tall fescue seed field will need a combination of water stored in the profile over winter and irrigation to meet this water use for best seed yields especially if rainfall is short of this 10.1 to 10.5 inch total.

Spring rainfall at Corvallis averages 5.8 inches, but the crop water use need exceeds 10 inches on a medium textured soil. Our results indicate that a single irrigation (over a few days) of 3.7 inches timed at early flowering (BBCH 60) resulted in a seed yield increase of 16% in perennial ryegrass.  However, the highest perennial ryegrass seed yield increase of 25% was made possible with multiple irrigations (total irrigation water = 6.5 inches) timed between spike emergence (BBCH 50) and peak flowering (BBCH 65).
Continue reading →

Grass seed crop growth and development advanced again

Posted on by

Thomas G. Chastain

Growth and development of grass seed crops are progressing at a faster rate than is usual for the Willamette Valley as a result of warm winter and spring temperatures in the 2015-16 crop year (Fig. 1).  The same pattern was observed in the 2014-15 crop year.  These crop years were both much warmer than the average temperatures observed for the region and this is reflected in the growing degree days (base temperature = 5°C or 41°F) accumulated during the crop years.

Figure 1. Growing degree days (GDD) for the crop year through April 21 at Corvallis, Oregon.
Figure 1. Growing degree days (GDD) for the crop year through April 21 at Corvallis, Oregon.

 

These warm temperatures in the past two crop years are the result of strong El Niño conditions that have been prevalent.  The effect of more growing degree days (GDD) accumulated earlier in the crop year drives development of the crop so that stages of crop development are reached at earlier calendar dates.  In other words, the crops are progressing toward maturity at a faster rate than seed growers might otherwise expect.  Certain management practices like PGR applications and others are taking place earlier in the season as a result.

One aspect of the 2015-16 crop year that is different than in 2014-15 is the high precipitation in the current crop year.  While it has been warm, it has also been wet.  Last year was marked by severe drought conditions.  Looking ahead, scientists are projecting that the El Niño conditions have waned and that there is a possibility of cooler weather in the next crop year.

OSU Seed Production Field Days

Posted on by

OSU is presenting two seed production field days in May where the public can visit research farms and learn more about research activities. The field days provide a convenient choice for those located in either the western or eastern parts of the state.

May 25 – Hyslop Farm Field Day – Plant growth regulators and nutrient management in grass seed crops, plant growth regulators and irrigation management in clover seed crops, weed management in grass seed crops, cereals, and more. Starts at 8:15 AM and ends with lunch provided by the OSU Crops Club.

Located at Hyslop Crop Science Field Research Laboratory just off Highway 20 between Corvallis and Albany at 3455 NE Granger Corvallis, OR 97330. Phone (541) 737-6067. Hyslop Farm location

May 26 – Grass Seed Field Day – Various topics focused on grass seed production practices and pests and more. Starts at 8:00 AM and ends at noon.

Located at OSU’s Hermiston Agricultural Research and Extension Center, 2121 S. First Street, Hermiston, OR 97838. Phone (541) 567-6337.

Winter Cutworm: Pest in Willamette Valley Seed Crops

Posted on by

Seed growers are reporting winter cutworm in Willamette Valley seed fields this fall and early winter.  The extent and severity of this pest in fields is unknown at this time as is the potential for future seed yield loss.  A new OSU Extension publication addresses the pest and problems it may cause.  The publication can be found at the link below:

Winter Cutworm: A New Pest Threat in Oregon

EM9139 cover image