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Old 06-09-2013, 02:30 PM   #1
Jul 2009
Posts: 24

I'm in my third year for some plants and 2nd year for about half the
plants, this year the challenge might not be critters but mildew.
Centennnial was the first to surpass the 18+ foot height yesterday
with many more to follow soon. I have chinook, centennial,
columbus, cascade, northern brewer, willamette, nugget.

Overall most of my plants seem to be doing well except I am noticing
some black spots on the underside of leaves (mostly near the bottom
still) and I pick these off. I have thinned most of the bottom leaves
and notice they seem to be the most affected. The pic shows
what the black looks like at the start, it will progress throught the
whole leaf. The second to last picture shows the top of the bine which is
about 11 feet tall and may be infected, I pulled a lot of blackend
leaves off this (columbus) and it also had a bine which was different
light shades of green and I clipped that bine completely off it.
The last pic shows a some sidearm that never started and seem
to dry out and I noticed some black there as well.

I am wondering if this is the downy mildew and what I should be do?

I sprayed with some copper fungicide a couple week ago. But I am not sure what the treatment might be and how to keep this from spreading across the yard?

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Old 06-09-2013, 03:20 PM   #2
Jul 2009
Posts: 24

Better close up of damaged leaf
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Old 06-09-2013, 03:52 PM   #3
Dec 2010
Langley, BC
Posts: 934
Liked 24 Times on 23 Posts

Yes, that is downy mildew. Note how the brown lesions are limited by the leaf veins, this is classic downy mildew.

Copper will help somewhat for downy mildew, but the most important factor for downy mildew control is the environmental conditions. It seems like you have a significant amount of morning and evening shade for your hops, and this will allow the morning dew to sit on the leaves for an extended period of time. This free water on the leaves will allow the downy mildew to sporulate, and then spread to adjacent plants. If at all possible, try to reduce the amount of shade the plants recieve. Also, remove any diseased leaves as they only increase the amount of inoculum present in the area.

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Old 06-10-2013, 12:06 PM   #4
Jul 2009
Posts: 24

Thanks for the good info, you are
Correct about early morning and
Late afternoon shading.
I 'm guessing it takes a until 9 or
10 before the sun reaches the
Plants, then the bases are out
Of the sun by 6 or so.

Unfortunately I don't Think I can clear much of the

I know the bases take the longest
For the sun to hit so hopefully
Concentrating there and removing
Leaves and periodic spraying I
Can keep it in check.

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