Our greatest challenge in the 1996 study was winter mortality. We will report winter mortality in the Spring of 2000. Thus it appears for optimum growth in the Klamath Basin, soil with a pH around 7.5 works well. Following the practices being used by other poplar growers, we opted not to mechanically cultivate during this growing season. Some researchers have reported that mechanical cultivation may stunt growth by damaging the shallow roots of the trees.
Herbicides are therefore the preferred method of weed control.
As an alternative, we manually removed the larger weeds and planted a winter wheat cover crop. Research conducted at the Malheur Experiment Station indicates that cover crops reduce tree growth. In October, the heights of all the trees were measured. For those trees that survived last winter, average height is now nearly 12 feet for the north plot, and for the west side of the south plot. At the end of the first growing season, the trees in the western edge of the south plot averaged nearly a foot taller than those in the north plot.