Potato Grower

62 POTATO GROWER | JANUARY 2022 DIGGIN' IN HERBICIDES | By Albert Adjesiwor, Nora Olsen & Pamela Hutchinson Herbicides are an important weed management tool for agriculture. The use of herbicides in multiple crops makes it necessary to track what has been applied to crops in rotation with potatoes to avoid damage due to carryover from the previous season(s). The time after an herbicide is applied and when a particular crop can be planted in ensuing growing seasons is called plant-back interval, plant-back restriction ,or another similar term. This information is listed on herbicide labels. The table below outlines examples of commonly grown rotation crops and applied herbicides, and the required plant-back interval for potatoes. Tracking herbicide use in previous crops before planting potatoes can be complex, especially if the land is being rented or leased. But this is extremely important to avoid any unnecessary damage to the potato crop. The risk of herbicide carryover from one crop to the next is determined by a myriad of factors including but not limited to: 1. Type of herbicide and chemical structure influencing the innate persistence of herbicides in the soil: Some of these characteristics can result in slow or no metabolism and/ or chemical processes, so a particular herbicide might persist longer in the soil than others. 2. Soil type and characteristics: Heavy soils tend to prolong herbicide persistence in the soil. Soil pH and organic matter also affect herbicide persistence considerably. Read the label carefully to understand how your soil characteristics may affect rotational crop restrictions. 3. Late-season application timing or high rates: This can lead to not enough time with optimum conditions needed for herbicide breakdown before potato planting. 4. Amount of moisture: Most herbicides are broken down by soil microbes and various chemical processes. These processes all require soil moisture. Dry weather means all these processes would either be slowed down or Beware of herbicide carryover Long-Term Danger Small grain and fallow: 2 metsulfuron-methyl (Ally® XP) .................................................................... 34 4 quinclorac (Facet® L) ..................................................................................... 24 2 thiencarbazone-methyl (component of Huskie® complete) ................... 18 8 triallate (Far-Go®/Avadex®) .......................................................................... 12 2 mesosulfuron-methyl (Osprey®) ................................................................. 10 2 flucarbazone-sodium (Everest®) .................................................................. 9 2 pyroxsulam (PowerFlex®) ............................................................................. 9 27 pyrasulfotole (component of Huskie®) ....................................................... 9 Sugar beet: 4 clopyralid (Stinger®) ...................................................................................... 18 8 ethofumesate (Nortron®) .............................................................................. 12 Alfalfa, dry beans, and other crops: 2 imazethapyr (Pursuit®) ................................................................................ 26 5 terbacil (Sinbar®) ........................................................................................... 24 2 imazamox (Beyond®/Raptor®) (also used in Clearfield® Wheat) ........... 18 14 saflufenacil (Sharpen®) ................................................................................ 9 27 topramezone (Impact®) ............................................................................... 9 Months after application before potatoes can be planted Herbicide site of action group Use crop and active ingredient (Example of commercial product, but note that not all products are listed)*

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