TIMING OF HERBICIDE APPLICATION AND POTATO HILLING

Weed management involving the time of hilling and various herbicide applications was compared. The best weed management program consisted of EPTC (S-ethyl dipropylcarbamothioate) at 3.3 kg ai ha-1 preplant incorporated, followed by metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] at 0.6 kg ai ha-1 applied delayed preemergence, or delayed preemergence applications of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] plus linuron [N'-(3,4-dichlorophenyl)-N-methylurea] (2.2 + 1.1 kg ai ha-1) or metolachlor plus metribuzin (2.2 + 0.6 kg ai ha-1) regardless of the time of hilling. Alternatively, postemergence applications of sethoxydim [2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one] plus metribuzin plus crop oil concentrate at 0.2 plus 0.6 kg ai ha-1 plus 1.2 L ha-1 provided excellent season-long weed control regardless of the time of hilling. However, potato yield was reduced in 1 of 2 years by this treatment. Preemergence herbicides applied immediately after planting followed by an early hilling at ground cracking did not provide season-long weed control. The cultivar Atlantic was a better competitor with weeds than Russet Burbank in 1 of 2 years.