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Weed Control in Potatoes

From the Pacific Northwest Weed Control Handbook
Herbicide Application and Remarks

Potato Vine Kill

Rate: 0.75 to 1 lb ai/A (1.5 to 2 gal/A) 
Time: Apply 10 to 14 days before harvest. 

Remarks: Use higher rate during cool or cloudy weather or when vine growth is heavy. For ground applications, the addition of 3 to 5 gal/A of diesel fuel or 1 pint paraffin- base herbicidal oil for each 20 gal total spray may increase speed and overall vine kill. No wetting agent or emulsifier is required; endothall will emulsify diesel fuel or herbicide oil. Add diesel oil last to avoid possibility of forming an invert emulsion. 

Caution: A restricted-use herbicide in Oregon. Do not use high rate, diesel fuel, or other oils if soil moisture is low or temperatures are high, or stem ends may discolor. 

Rate: 0.25 lb ai/A (1 pint/A) or up to 0.5 lb ai/A (2 pints/A) in a single application.  
Sequential applications may be made, but do not exceed a total of 0.75 lb ai/A (3 pints/A) per season before harvest. Idaho, Oregon, and Washington special local needs labels (ID-960014, OR-960034, WA-960028). 

Time: Make last application at least 7 days before harvest. 

Remarks: Do not apply more than 0.5 lb ai/A (2 pints/A) in a single application. Apply with a nonionic surfactant at 8 to 16 oz/100 gal spray mix. Allow at least 5 days between applications. Do not apply through any type of irrigation system.

Caution: A moderately toxic herbicide that requires protective gear for handling and  
application. Follow all use restrictions and precautions given on label. Do not apply to drought-stressed potatoes. Make last application at least 7 days before harvest. Do not feed forage from treated potatoes to livestock. 

Gramoxone Extra
Rate: 0.25 to 0.47 lb ai/A (0.8 to 1.5 pints/A) + nonionic surfactant at 16 to 32 fl oz per 100 gal spray mix

Time: Make last application at least 3 days before harvest. 

Remarks: Apply in 50 gal/A water with thorough coverage. 

Caution: A restricted-use herbicide. Follow all restrictions and precautions on label. Do not apply more than twice with a minimum of 5 days between applications. Do not apply to potatoes within 3 days before harvest. Do not use paraquat if potatoes are to be stored or used for seed. Do not pasture livestock in treated fields.

sulfuric acid (93%) Rate: 17 to 28 gal/A

Time: At least 5 days before harvest. 

Remarks: This material is not as dependent on temperature or other environmental conditions as most other desiccants. 

Caution: A restricted-use herbicide. Sulfuric acid is very caustic. Protective clothing including dust/mist filtering respirator, chemical-resistant headgear, protective eyewear, chemical-resistant boots, and waterproof gloves must be worn. 

Rate:  20 gal/A diluted 1:1 with water for 40 gal/A
Time: No specified time; allow adequate time for skin set. 
Remarks: Must be applied diluted. Surfactant must be added. This material is much safer to user (less caustic to skin), but is as corrosive to cotton, nylon, and some other materials as sulfuric acid. Consult label for full directions.

Caution: Do not mix sulfuric acid and urea to make this solution. Use the premixed solution. 

OSU Disclaimer

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For additional information about the Malheur Agricultural Experiment Station weed control program, please contact Dr. Corey Ransom.

Malheur Experiment Station
595 Onion Avenue
Ontario, OR 97914
(541) 889-2174
FAX (541) 889-7831