Abstract
Effectively topping sugarbeets during early harvest has been a struggle for Michigan sugarbeet growers. To address this concern various products were applied as harvest-aids 6 d prior to topping in early September 2024. Products used as harvest-aids were sodium chlorate (Defol 5) at 7.8 and 15.6 kg ha, calcium (Max-In Calcium) at 1.2 kg ha, paraquat (Gramoxone) at 0.55 kg ha, saflufenacil (Sharpen) at 50 g ha, diquat (Reglone) at 0.56 kg ha, and a paraquat + saflufenacil tank-mixture. Sodium chlorate and saflufenacil treatments were applied with methylated seed oil and a non-ionic surfactant was used with diquat and paraquat alone treatments. Leaf desiccation was evaluated 2 and 6 d after treatment (DAT) on a scale from 0 to 100%. Sugarbeet leaf regrowth was also evaluated. Sugarbeets were topped, and leaf removal was evaluated. Roots were sub-sampled and analyzed for purity, % sugar, and recoverable white sugar per kg (RWSkg) of root tissue. Sugarbeet leaf desiccation was the greatest with diquat (84%), 2 DAT. Desiccation with paraquat alone and with saflufenacil was ~75%, 2 DAT. All other treatment provided less than 10% leaf desiccation. By 6 DAT, leaf desiccation with diquat and paraquat treatments were similar and sodium chlorate leaf desiccation was 32 and 42% with the low and high rates, respectively. Calcium had virtually no visual effect on leaf tissue and saflufenacil only resulted in slight leaf speckling (12%). There was also 17-20% leaf regrowth with the diquat and paraquat treatments. No treatments improved the effectiveness of leaf removal from topping compared with the untreated control. In fact, leaf removal was significantly lower (10% or more) when leaf desiccation was high, diquat and paraquat treatments. All preharvest treatments with the exception of saflufenacil and calcium reduced RWSkg by 8% or more compared with the untreated control. In conclusion, the use of preharvest treatments were not effective in improving sugarbeet topping and other techniques or system changes will likely be needed to improve leaf removal from topping operations during early harvest.
