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.

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.