Brown areas on Hop leaves

Question: I have a hop vine, about 8 years old, grown for decoration and trained horizontally on wires on the west side of my house.  It has never had any disease problems in the past but I was out of town last week and returned to find it developing brown spots and patches on older. lower leaves.  It is watered by a soaker hose and grown in a large nursery pot with the bottom cut out.  Can you tell me what the problem most likely is?

responder: Kevin K.  Replied June 07, 2023, 11:30 AM EDT
response: Thank you Jan for your question to "Ask Extension".  The pictures that you provided were excellent but inconclusive.  I have tried to match them with all pest and fungal and viral diseases in hops without success.  Since you stated that this is only on older growth and happened in a very short time period I suspect that this might be some kind of chemical (herbicide) drift.  I would be very interested in knowing if any future growth may have similar damage, including new growth and the cones.  I have provided you with a link to the extensive website that I referenced for my response. http://ippc2.orst.edu/hop/HopHandbook2010.pdf      I hope that this information is useful.  As always Happy Gardening.

responder: The Question Asker Replied June 07, 2023, 6:33 PM EDT
response: Kevin- Thanks for the response.  As far as I know, there has been no herbicide sprayed anywhere near the hop vine and it's pretty isolated from any possible drift but I'll keep an eye on the new leaves and cones and report further damage.  Thanks for the info link, also.JanOn Wed, Jun 7, 2023 at 8:30 AM Ask Extension <<personal data hidden>> wrote:

responder: The Question Asker Replied June 09, 2023, 7:02 PM EDT
response: This is in response to Kevin K (Benton County)'s answer on 6/7 concerning brown spots on my Hop leaves......(that thread was closed.) Kevin:I had found this earlier on the Michigan State University Extension  website (but can't find exact link again!  - there was more info on it)  There was a photo VERY similar to the leaves on my hop and they labeled it as Downy Mildew!!"As the season progresses, symptoms may include stunted side-arm growth, tip die-back and cone discoloration. The fuzzy, visible growth of downy mildew is not always present and should not be relied upon as the sole indicator of whether infection is present."That was the closest I could find to an explanation.....it's still a mystery but some of the newer leaves seem to be showing the same symptoms, BUT---they look like they may all be originating from the same bine!  I am going to TRY to remove that bine and it's off-shoots and see if the problem continues.JanOn Wed, Jun 7, 2023 at 8:30 AM Ask Extension <<personal data hidden>> wrote:

responder: Kevin K.  Replied June 10, 2023, 12:38 PM EDT
response: Jan,       I had a similar thought.  Downey mildew usually require a damp or humid condition.  Since we have not had any rain for the last five weeks and that you use a soaker hose for irrigation I couldn't see where the environment was conducive for mildew growth.  When you remove the bine look carefully to see if it is swollen and has dark growth in the center as that would be helpful information also.

responder: The Question Asker Replied June 10, 2023, 1:50 PM EDT
response: Thanks!  I'll try to get that done in the next couple of days! JanOn Sat, Jun 10, 2023 at 9:38 AM Ask Extension <<personal data hidden>> wrote:

responder: The Question Asker Replied July 15, 2023, 2:26 PM EDT
response: Kevin-   Sorry to be so long in updating but the browning of leaves did expand......BUT-- only on that single bine!  The rest of the plant has had no symptoms. Jan