Grass seed farmers burn their fields after harvest to kill off weed seeds and plant diseases. There has long been a controversy over the effect of the smoke especially on people with asthma or other respiratory disease. Gov. Ted Kulongoski will ask the 2009 legislature to phase out field burning in the Willamette Valley by 2016. Burning limits would be cut back starting in 2009, followed by further reductions until the practice is phased out in 2016.
According to a FAQ sheet issued by the Oregon Department of Environmental Quality (DEQ), "Field burning disposes of leftover straw and stubble on fields after grass seed harvesting. It controls weeds, insects and plant diseases which helps maintain grass seed purity, reduces use of pesticides and herbicides, and improves yields. Alternatives to field burning are currently practiced throughout the Willamette Valley. These include crop rotation, chemical applications, straw removal and propane flaming."
In 1988 a change in the wind caused a cloud of smoke to drift over Interstate 5, decreasing visibility which caused a 23-vehicle pileup that left seven dead and 38 injured.