NDSU Potato Blightline 15 July 2019. Late blight has not been reported in ND, MN or MB in 2019, but late blight severity values (DSV’s) in all potato growing areas have exceeded 15, the critical risk value at which late blight infection will occur if inoculum is present. Late blight disease risk values (DSVs) have increased due to the recent and plentiful rains. All growers and consultants should be scouting fields for late blight and apply a protectant fungicide at weekly intervals beginning at row closure. P-Day values are over 400, a critical threshold for early blight management and protectant fungicides should be applied. Remember to send suspect late blight samples to us for positive identification. Let us know if you have questions or suggestions.

-Gary