Downy mildew (Pseudoperonospora humuli, Miyabe and Takah., Wilson) was one of the major reasons for the decline of hops production in the Northeast over a hundred years ago. As many of you know, it is still a significant issue here, as well as in yards in the major hop growing areas of the United States and Europe. While P. humuli is closely related to the downy mildew that you can find on your watermelons, cucumbers, and zucchinis, the organism does not cross infect, meaning that you don’t have to pull out your squashes to spare your hops, or vice versa. Downy mildew can cause the complete loss of marketable yield, and even hill death in sensitive hop varieties. It is a very serious hindrance to successful hops production, but diligent integrated pest management (IPM) can help you manage the disease in your hopyard. Click here for more information on downy mildew and for best management practices concerning the disease.
For some neat videos on pruning hops in the Pacific Northwest, and to see some of the latest research on fungicide efficacy, check out the Northwest Hop Information Network’s Facebook page.