Comparing Sugar Beet Productivity, Weed Incidence and Management in Three Tillage Systems.
Sugar beet is an important irrigated crop in Idaho and ranks third nationally in sugar beet production, producing more than 4.78 million metric tons in 2010. Since the introduction of Roundup Ready sugar beet in 2008, weed control in sugar beet has greatly improved for Idaho and eastern Oregon growers compared to non-Roundup Ready sugar beet. Sugar beet grown using strip tillage, a form of reduced tillage, was first tried in Idaho in 2009. Consideration of growing sugar beet using strip tillage was made possible because of Roundup Ready sugar beet. Weed control with conventional sugar beet had long been considered one of the biggest challenges for producing a successful sugar beet crop. With conventional sugar beets, multiple tillage operations during the growing season are usually required in addition to herbicides for weed control. The
introduction of Roundup Ready sugar beet has opened the opportunity to commercially grow sugar beet with reduced tillage. Prior to the availability of Roundup Ready sugar beet, conservation tillage research had been conducted in sugar beet dating back more than 35 years. However, it did not generate much interest primarily because of the need to cultivate for weed control in sugar beet due to the ineffectiveness of available herbicides. For the most part, weed control in Roundup Ready sugar beets has been quite successful. Our research thus far shows that weed control with glyphosate alone applied 3 or 4 times during the growing season will control nearly all weeds through the growing season without having to cultivate. However, concerns about glyphosate resistant weeds have prompted evaluating tank mixtures of glyphosate with soil-active herbicides, such as ethofumesate, dimethenamid-P,
s-metolachlor, EPTC and cycloate. Field studies thus far show these combinations can be an effective weed management strategy in Roundup Ready sugar beets grown under conventional tillage systems. However, it is not clearly understood if or how weed control in strip tillage or direct-seeded sugar beet using soil-active herbicides, such as acetochlor, dimethenamid-P, ethofumesate, EPTC and s-metolachlor with glyphosate may be influenced by the presence of crop residue on the soil surface.