Is it downy mildew? Do I need to be worried?

I noticed that something is causing some angular lesions on my second year cascades, as well as some some discolored, whitish looking decay around the edges. The highest leaves were looking a bit yellowish, as well. Now that they've grown a bit higher, I'm noticing the same lesions but less discoloration the mature leaves higher up on the bine.

For what it's worth, these guys were planted last year next to a Fuggle that came up looking pretty scraggly, and barely topped out on the 6 foot stake it was trained on. The leaves on the Fuggle were either completely yellowed or really shriveled, curled, and wilted looking. It didn't come up at all this year. So: if that was some kind of mildew or virus, could it have spread to these cascades in the next spots?

For what it's worth, the cascades are growing pretty well, and are already about 8' up their lines after being trained about a month ago.

So: do I need to do about this, or just wait and see? I know to keep my eye out for the sporangia on the bottoms of the leaves, but that those aren't always present. I've also read that one thing to do is take off the lowest foliage to minimize transmission and so things air out a bit better. Is that okay to do at this point, now that the bines are all well-established?

Thanks for any help.

look here:
http://5e.plantphys.net/article.php?ch=t&id=289

It is not downy mildew. Those "angular lesions" look like thrips feeding damage, or maybe some kind of mechanical damage (small tips bumped against the stake by something), and the yellowing looks like general Nitrogen deficiency.

theredben said:

It is not downy mildew. Those "angular lesions" look like thrips feeding damage, or maybe some kind of mechanical damage (small tips bumped against the stake by something), and the yellowing looks like general Nitrogen deficiency.

Click to expand...

Agree.. Possibly magnesium deficiency too, but more than likely just need some general fertilizer.

Not powdery mildew. That looks exactly as it sounds. Will leave a powder on your fingers. Looks like an Mg deficiency, possibly a Ca deficiency if the necrosis on the margins is similar. Could be some sort of leaf eating insect tho too as far as the damage to the margins.

Put some compost on it and see what it does!

Thanks a lot folks, and please pardon my hypochondriac (hopochondriac?) tendencies!