Selectivity of pre-emergence herbicides in potato cv. Innovator

ABSTRACT Herbicide tolerance differs among potato cultivars. Thus, pre-emergence herbicides in potatoes need to be studied. We evaluated weed control, selectivity and potato yield of cv. Innovator with the herbicides clomazone, metribuzin and linuron. The experimental design was randomized blocks with four replications. One experiment was installed in 2014 (experiment 1, 5 treatments) and another in 2015 (experiment 2, 7 treatments), irrigated by central pivot in Perdizes-MG, Brazil. In experiment 1 treatments consisted of a control (T1), a hoed control (T2), clomazone (360 g ha-1) (T3), metribuzin (480 g ha-1) (T4), and linuron (990 g ha-1) (T5). The treatments in experiment 2 repeated those in experiment 1 (T1 to T5) and added clomazone + metribuzin (360 + 480 g ha-1)) (T6), and clomazone + linuron (360 + 990 g ha-1) (T7). We determined the number of stems per meter, length of longest stems, phytotoxicity, weed control, soluble solids content (%), yield and classification of tubers. The herbicides, either by themselves or in combination with another herbicide, provided 100% control of Eleusine indica and Digitaria horizontalis. Clomazone by itself or in combination with metribuzin or linuron provided the best control of Commelina benghalensis. Plots treated with clomazone presented phytotoxicity symptoms at 10 days after emergence (DAE); however, the plants recovered from these symptoms at 30 DAE. Metribuzin reduced soluble solids content, which affects industrial yield. The herbicides significantly influenced potato yield. In, 2014, the greatest “total” yields were observed in treatments with linuron (34.48 g ha-1) while the greatest “special” potato yields were achieved with clomazone (20.21 g ha-1) and linuron (21.13 g ha-1). In 2015, the greatest “total” yields were observed in treatments with clomazone [“special” (20.98 t ha-1) and “total” (35.11 t ha-1)] and metribuzin [“special” (20.85 t ha-1) and “total” (35.45 g ha-1)] followed by clomazone+linuron (30.95 g ha-1). Therefore, while metribuzin and linuron controlled Eleusine indica and Digitaria horizontalis, they may also reduce potato quality. Clomazone may be an option for controlling Eleusine indica, Digitaria horizontalis and Commelina benghalensis without affecting potato yield and soluble solids content.