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Iowa

Can any one please ID this disease/problem on my AG's?
Here is a link to my diary

http://www.bigpumpkins.com/Diary/DiaryViewOne.asp?eid=73559

It started a few days ago and at first I thought maybe I applied too much calcium, but now it appears to be spreading. I do have daconil, Headline, or Ouilt which I could try. I was wondering if there was something better for this particular diesease or if there is not much I can do.
Thanks
Ralph Trumm

8/29/2007 8:17:57 AM

Menomonie, WI (mail@gr8pumpkin.net)

It almost looks like a burn. Have you used Sevin or another pesticide lately. How old are the leaves in question? The lack of green pigment also concerns me.

8/29/2007 1:44:06 PM

Anamosa, IA BPIowegian@aol.com

Ralph, with all of the rain and high humidity we have seen in the past few weeks and your straw mulch, it looks to me to be some kind of fungal infection. Something you normally wouldn't see on your well drained soil, but it looks a lot like what I have been battling for the past 2 years on my creek bottom.

Are any of the new leaves getting a mottled,yellow-green color or is it just on the older leaves? I would also check the bottoms of some of the vines, especially where the root comes out at the leaf note. Mine were starting to show some brown rot on the bottom of the vine, and some rotted half-way through at the root. I hope someone can get you an answer soon. When my plants started looking sick they went down real fast.
Mark

8/29/2007 1:51:42 PM

Iowa

I used Baythroid about a week ago. It is a pyrethrin simular to Warrior. It was sparyed in the evening though, and it rained the next morning. I would think it would not have burned it, but you are saying maybe? Wouldn't that show up right away and not get worse?
Ralph

8/29/2007 1:56:35 PM

Wi

I'm concerned when I see that mulch also. The mulch alone isn't bad, but the rain we've gotten lately combined with the mulch scares me.

8/29/2007 2:12:53 PM

Mt.Pleasant,Iowa

Im not sure Ralph either, It may be like they say with all the rain and the mulch.The roots cant breath and the nitrogen washing away.We are to have plenty of sun and drier weather maybe they will improve,Good Luck ! Marty

8/29/2007 10:06:11 PM

Eugene, OR

Hi Ralph, I'm no pathologist but that looks a lot like what I had on one of my plants this year. I did not have a tissue test done. but all my research online pointed to downy mildew. In bad cases, the spore colonies under the leaves can be seen by the naked eye, although they weren't visible on my leaves. However, a "bag test" of one of the infected leaves led to a large enough spore colony for me to see it.

I just cut one of the leaves, put a piece of the infected tissue in a ziploc bag, added a little moisture, and kept it in a warm spot. If it is downy, the spores should be visible after a day or two. An example pic of downy: http://www.ces.ncsu.edu/depts/pp/cucurbit/images/i03b.JPG
More about downy: http://www.ces.ncsu.edu/depts/pp/cucurbit/images.php

Sorry I can't be more help and hope it works out for you!
Brian

8/29/2007 11:32:32 PM

Ctpumpkin@optonline.net

It doesn't look like spray injury. Baythroid is a low dose material & the application sounds correct so...

Downey Mildew usually isn't as localized as this so I doubt it too.

Have you checked the leaf undersides really well? Mite or thrip damage might look like this under certain conditions.

8/30/2007 12:51:18 AM

Iowa

Steve,
I have not seen any mites or Thrips. I have looked pretty close for them, maybe not hard enough. (second guessing myself) One thing I know for sure is that it is mainly only one side of the plant. It starts along the main vine and moves east to side vines on the east side of the plant. So, seems to be spreading with the wind? Do any of you think it could be angular leaf spot? I don't know for sure what that looks like.
thanks
Ralph

8/30/2007 8:28:28 AM

Hayward, CA

Sometimes I can find something on these two websites that resembles what I am trying to identify. Tough to see only a small area in a picture for comparison. Good luck!

http://aggie-horticulture.tamu.edu/Cucurbit/indexleaf.html

http://vegetablemdonline.ppath.cornell.edu/factsheets/Cucurbits_Foliar.htm

Puter

8/30/2007 11:23:22 AM