Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 1, 2000
Publication Date: February 1, 2001
Citation: Boydston, R.A., Alva, A.K. 2001. Volunteer potato control in onions with herbicides and cultivation. Weed Science Society of America Meeting Abstracts. Vol 41:10 #22. Technical Abstract: Potato tubers left in the ground after harvest often fail to freeze in mild winters in the Washington state and are serious weed problems in rotation crops. Studies were conducted in 1996 and 2000 to evaluate sequential herbicide treatments combined with repeated cultivation for control of volunteer potatoes. Ethofumesate was applied both preemergence and postemergence, and bromoxynil, oxyfluorfen, bromoxynil plus oxyfluorfen, clopyralid plus bromoxynil, and fluroxypyr plus bromoxynil were applied postemergence at various rates and times of application. Postemergence treatments were applied when onions were in the two, three, and four to five leaf stage in both years. Plots were cultivated with sweeps at 7 to 10 days after each postemergence herbicide application. Potato tubers and onions were dug, counted, and weighed in late August in 1996 and early September in 2000. Ethofumesate applied preemergence slightly delayed potato emergence and caused epinastic and stunted growth of potatoes. Bromoxynil applied postemergence slightly injured potatoes but did not reduce potato tuber weight as much as oxyfluorfen, fluroxypyr plus bromoxynil, or clopyralid plus bromoxynil. Three applications of oxyfluorfen or oxyflurofen plus bromoxynil, two applications of either clopyralid or fluroxypyr plus bromoxynil, or three applications of ethofumesate plus bromoxynil combined with cultivation at 7 to 10 days after herbicide applications, controlled volunteer potatoes season long and reduced potato tuber weight and number the most. However, only sequential applications of oxyfluorfen or oxyfluorfen plus bromoxynil combined with cultivation controlled potatoes well without injuring onions and reducing onion yield compared to hand weeded checks.