Submitted to: Proceedings Washington State Potato Conference
Publication Type: Proceedings
Publication Acceptance Date: 2/1/2005
Publication Date: 5/1/2005
Citation: Boydston, R.A., Hutchinson, P.J., Ransom, C. 2005. New herbicides for weed management in potato production. Proceedings 44th Washington State Potato Conference. Pg. 1-3. 2005
Technical Abstract: Weeds reduce potato yield and quality and the cost of controlling weeds increases the overall cost of potato production. Several weed species are not consistently controlled by metribuzin which is used on more potato acres than any other pesticide. Dimethenamid-p, sulfentrazone, and flumioxazin are new herbicides that control hairy and black nightshade, two weeds often not controlled in potato production. These three herbicides were tested over several years in potatoes for crop tolerance and weed control near Aberdeen, ID, Ontario, OR, and Paterson, WA. At all locations herbicides were applied after the final hilling and prior to potato and weed emergence, and sprinkler incorporated. Dimethenamid-p controlled barnyardgrass, crabgrass, yellow foxtail, green foxtail, and small-seeded broadleaf weeds hairy and black nightshade and pigweed species alone and in tank mixtures with other herbicide registered on potato. All major potato varieties grown in the PNW exhibited good tolerance to dimethenamid-p. Sulfentrazone applied preemergence controlled pigweed species, hairy and black nightshade, common lambsquarters, kochia, and Russian thistle. Grass weeds were not controlled well with sulfentrazone at rates used in potatoes. Grass control was improved by tank mixing sulfentrazone with metribuzin, s-metolachlor, rimsulfuron, pendimethalin, or EPTC. All major potato varieties grown in the PNW exhibited tolerance to sulfentrazone. Some injury was observed on potato leaves in late May and early June when using higher than labeled rates of sulfentrazone. Minor to moderate injury symptoms on leaves have not resulted in reduced tuber yields in research trials unless the potatoes were experiencing heat stress at the same time as metabolizing the herbicide after root uptake. Flumioxazin controlled pigweed species, hairy and black nightshade, common lambsquarters, kochia, and Russian thistle. Nightshade species are very susceptible to flumioxazin and its use in potato will primarily be targeted as a tank mix partner to improve nightshade control. Pigweed and common lambsquarters control with flumioxazin was less consistent in silt loam soils with higher organic matter in Idaho and Oregon than in sandy soils with low organic matter in Washington State. Grass weeds were not controlled well with flumioxazin at rates labeled for potatoes but was improved with tank mixing with metribuzin, s-metolachlor, rimsulfuron, pendimethalin, or EPTC. Major potato varieties grown in the PNW exhibited good tolerance to flumioxazin.