Exploring Early Planting Dates for Winter Canola in the Inland Pacific Northwest.

In the Pacific Northwest region of the U.S.A, winter canola is typically planted on summer fallow during August or early September to allow enough growth in the Fall for the crop to establish before the onset of winter.  In order to take advantage of soil moisture for establishment and to better balance work loads, growers have shown considerable interest in planting dates during late June or early July.  To investigate the feasiblity of early planted winter canola, several separate experiments have been conducted to examine winter hardiness, moisture use, seeding rates, response to nitrogen applications, and response to insecticides. Winter canola planted in June significantly reduced soil moisture in mid-October in both the top foot and second foot of soil as compared to a traditional seeding date.  Despite significant reductions in soil moisture, average seed yield was not significantly different between June and July plantings.  In one year of the studies, yield of winter canola planted in August was significantly reduced at each of the sites examined when compared to yields from the earlier plantings, and the August planting at at one site failed to establish as a result of low soil moisture in the seed zone.  In another year, the yield of the earliest planting was reduced compared to a traditional planting date due increased winter damage in the early planted crop.  Seeding rate did not significantly effect seed yield.  In three of four years, flea beetles and aphids caused serious damage to early planted winter canola in the fall of the planting year.  Without seed treatment or foliar insecticide application, plants were severely defoliated from insect infestation; however, this severe fall insect damage did not cause a difference in harvested seed yield when conditions allowed for regrowth during the Fall. Implications for growers will be discussed.