Herbicide carryover in sugarbeet – an assessment.
Chemical carryover from the previous crop into sugarbeet is a common problem that crop consultants and growers face each year in southern Idaho. Crops such as dry beans, potatoes, onions, and others allow chemicals to be applied that may be detrimental to sugarbeet if applied at the incorrect timing or if sugarbeet is planted earlier than is recommended by the guidelines found on the pesticide label. Often, time is of the essence when making management decisions once a problem of this nature is manifest in late spring. This study was designed to help growers and crop consultants make management decisions by assessing potential yield losses and other potentially negative effects several chemicals found in the rotation may have on the current sugarbeet crop under both tilled and no-tilled ground. Chemicals were applied in late spring of the previous year to bare ground and the ground was managed as if a crop existed for the remainder of the year. Tillage treatments were administered in late fall and sugarbeets were planted into the existing plots the following spring. Preliminary data show no significant differences between nitrates, percent sugar, or predicted thick juice purity between any of the treatments. The largest significant factor was yield for which imazamox, terbacil, and metribuzin exhibited the lowest yield in both tilled and no-tilled plots. Consequently, pounds of estimated recoverable sucrose per acre were also affected. No-till plots had significantly higher nitrates and conductivity and were slightly lower in pounds of estimated recoverable sucrose per ton and predicted thick juice purity than tilled plots. Losses in yield can be attributed to several factors including root structure, stand establishment and loss, and growth rate of the crop. Sugarbeets will be planted into the same area in 2023 to assess possible further damage from longer persisting chemistries. Results from this study including data, pictures, and symptom descriptions will help provide decision-making tools for growers and crop consultants facing challenging decisions should they experience chemical carryover in their sugarbeet crop.