Zucchini and Squash -What is killing mine suddenly?

Something is killing my zucchinis and squash plants, and I've never seen this before!

I'm using self-watering containers, built from the plans here (http://mckarion.wordpress.com/2009/11/29/frugal-gardner-self-watering-bucket/)
my soil is a great quality organic potting mix from a local nursery, mixed 50/50 with a local compost, and with some Plant-Tone mixed in.

Had great growth, then saw some powdery mildew. A mix of 2%milk and water seemed to take care of that, and spayed about once a week.

Then, suddenly, the entire plant turns yellow, there is browning on the edges of the lower leaves, and it seems to be dying.

Could it be too much nitrogen? Too much water? Help! Is there anything I can do to help, or is the plant done for? My pepper plants, cucumbers, and a variety of herbs and greens are doing fine, if bolting a bit (the lettuce, that is)

Attached is a photo I took on the 18th.

A close up of one of the browned leaves, photo also taken on the 18th

Now photos from this morning (22nd). It's looking pretty grim.

Look at the base of the plant, on the main stem and see if you see anything like sawdust oozing out of it. If so, it's a squash vine borer and not a problem with your soil or anything.

Thanks Stephanie! I'll do that when I get home, although I checked for that same thing a few weeks ago. Maybe I missed something....

Spray with the following: 1 tablespoon of epson salt to 1 quart of water.

All my veggies are in containers, Last week I noticed that one of the containers with yellow squash ... leaves were gradually developing a yellow hue. These leaves continued to go yellow .... but now the plants have more lustious green leaves than yellow leaves. When a leaf strys to show brown, I cut it off and trash it.

Looks familiar! I have a similar post on the Vegetable Gardening board. Some have suggested that chlorinated water may be the culprit. I thought mine was Downy Mildew, but could not account for the edges of the leaves turning brown. My problem did start while I was on vacation and had someone water my garden for me. (I had not watered - but did not want to leave that judgement call to others and loose my plants - should have just let them to themselves I guess)

I'll watch your post. Maybe you can compare my pics to your leaves. If it's the same. Might be a genetic issue with seed. (highly subject to disease, etc.) I bought transplants, so I can't even start to guess what seed company supplied the seed.

My squash looked like sgriffith's pics before I sprayed with the epson salt solution. You can do this every other week.

if you had too much nitrogen the leaves would be really dark in color, it looks like you need more nitrogen since they are so light green! Try adding more nitrogen!!

Hi Kat -

I had the same problem last year and never did find a solution. This year, the *same* thing started and I'm frustrated - but not out of hope. This year I'm doing the following, and it *seems* to be working so far:

1. Weekly feeding with a good quality fertilizer (I'm using Jack's as recommend by my local garden center http://www.amazon.com/Jacks-Purpose-20-20-20-Soluble-Fertilizer/dp/B002HJBMRW )

1b - I'm doing a foliar application of the fertilizer - once or twice a week put some in a spray bottle and spritz it on the leaves in the evening or very early in the a.m. (I've heard that if you do it later morning or mid-day the water droplets can cause leaf scald)

2. Keeping the area near the crown thorough weeded for good air circulation.

3. At the first sign of necrotic leaf tissue (the brown crap), I cut off that leaf at the base - I did my pruning over two days because I had at least 10 leaves with bad tissue and I wanted the poor thing to have time to recover)

So far (and this is just so far) my pumpkin is still putting out vine and is putting out new leaves to replace what I pruned AND (more important) I'm (so far) not seeing any new yellowing or browning).

The way I figure, what I'm doing may not be solving the problem, but it obviously isn't making it worse and the plant still looks healthy, so I'm going to keep on this track.

July 5th:
http://picasaweb.google.com/lh/photo/bF-xpCU1Fb6ZlPUbgDkAGA?feat=directlink

July 12
http://picasaweb.google.com/lh/photo/WnoHLK23G_30ps1BX54FDg?feat=directlink

Wow Chicago Ash- your July 5th photo looks like my zucchini leaves- since I am using enriched soil I was told I don't need to fertilize, but it looks like I need to start- your July 12th photo looks so healthy!

Chicago Ash, THANKS for the awesome how-tos!
Also, merrymath, I will keep that recipe in mind for next time.

Unfortunately, it seems like SVBs, as I did seem some sawdust at the base of the plants.

I'm interested in the chlorinated water theory. Before my water barrels were done, I was using city water that is chlorinated for watering. It didn't seem to affect any of my other crops though. Thankfully, I have now built a 100 gallon system and so will never have to use city water again.

In the end, I pulled up the two affected plants and tossed them. Will be planting fall crops in their containers soon. Thanks everyone for the advice! Glad to know I wasn't the only one affected. Also, great advice for next season, so I can keep a close eye and nip problems in the bud.

ShyTown,
What'cha got growing in the blue tub in your July 12th pic?