Management of nitrogen and phosphorus rates does not suppress Verticilliumwilt in Yukon Gold

Effect of nitrogen and phosphorus fertilization rates on the incidence of V erticillium wilt caused by Verticillium albo-atrum or V. dahliae and tuber yield in potato cv Yukon Gold was evaluated in field plots. In three years of study, V. albo-atrum caused a higher incidence of wilt symptoms (74%-100 %) than V. dahliae (5%-81%) resulting in lower marketable tuber yield. In p lots infested with V. albo-atrum, tuber yield ranged from 12.3-22.8 T ha(-1 ) compared to 18.1- 31.5 T ha(-1) in plots infested with V: dahliae. Applic ation of nitrogen above (280 kg ha(-1)) or below (70 kg ha(-1)) the recomme nded rate of 140 kg ha(-1) at planting did not suppress foliar symptoms or protect against yield loss caused by either V. albo-atrum or I: dahliae. Si milarly, phosphorus rate adjustments did not consistently affect disease in cidence regardless of the pathogen. Management of nitrogen or phosphorus fe rtility rates at planting does not appear to be a viable approach for suppr essing Verticillium wilt in the determinant, wilt-susceptible cultivar Yuko n Gold.