Sick cucumber, watermelon, tomato, and zucchini plants

[HappyValleyGarden]

Hi!

I'm a pretty inexperienced gardener, and this year I find myself dealing with a big group of sick plants—and I have no idea what to do! I need a visit from a veggie doctor. =) Any advice or suggestions (on what to do this year or how to prevent this from happening next year) would be greatly appreciated.

My garden: Since I don't have ground space, I planted a container garden. I used an organic potting mix (lightly fertilized) and a variety of containers. I planted seedlings in early June and have fertilized with a very mild mixture of fish emulsion twice since. I'm currently having trouble with my tomatoes, zucchini, watermelon, and cucumber.

Tomato: an indeterminate heirloom plant that's grown very tall. I pinch back suckers and removed all leaves below the first fruiting branch. I have a few green fruit, some of which are quite big. In the past two weeks, most leaves turned brown and dry around their edges; it seems to be slowly spreading into the leaves (pic 1).
[img]https://picasaweb.google.com/lh/photo/6rJ_8LhY6ROXBpTeD2FGVg?feat=directlink[/img]
Just yesterday I noticed soft black spots—fungus?—forming on some of the leaves (pic 2).
[img]https://picasaweb.google.com/lh/photo/_XqQP4jWCnb4qOZXNWbofQ?feat=directlink[/img]

Zucchini: I know, who has problems growing zucchini?! I didn't until 2 weeks ago, when the older leaves of the plant began to yellow, droop, and drop very quickly. (Pic 3 is one of the leaves that I cut off yesterday.)
[img]https://picasaweb.google.com/lh/photo/q4BKwXYjwEo9qL3GJ2i61w?feat=directlink[/img]
As you can see, the younger parts of the plant still seem very healthy, but from the stalk you can see how many older leaves I've lost (pic 4).
[img]https://picasaweb.google.com/lh/photo/Tg9vev9DskHsBeYsfoXJBQ?feat=directlink[/img]

Cucumbers and watermelon: I've trellised both of these and they seemed quite healthy, growing faster than I could keep them trellised, until about 3 weeks ago, when the growth on both slowed significantly. It was at the same time they began producing fruit, so I assumed that was the reason for the slow growth. Then about a week ago both began to have some yellow leaves. Leaves that looked perfectly healthy in the morning would turn light yellow by the time I got home from work and would sometimes shrivel and turn black. This happened to leaves all over the plants, not just at the bottom or on one vine or something. I've removed these leaves as much as possible, but they keep coming and the plants seem less healthy.
[img]https://picasaweb.google.com/lh/photo/hEXSuLr6East_aL4_DFyMg?feat=directlink[/img]
[img]https://picasaweb.google.com/lh/photo/CMjhOwgdX246ed6Kbw5kpg?feat=directlink[/img]

As I mentioned, I'm looking for any advice I can get, at all. (Do veggie doctors make house visits?!) Thank you so much for taking the time to read and consider. =)[/img]

[rainbowgardener]

You are asking a lot of volunteer question answerers... it's a long post, with a bunch of different questions and then to see the photos we have to fix your links (the img at the front makes the link not work) and then go look at each one individually.

Here's instructions on how to post pictures in this forum so that the picture is in the post and readers don't have to go look for it:

https://www.helpfulgardener.com/forum/viewtopic.php?t=3724

You will get more responses if you break this up into a few different posts each with the relevant picture embedded.

In the meantime, I will make a stab at one... The zucchini (pic 4) does look pretty healthy except on the small side. To be planted almost two months ago, we would expect it to be a lot bigger and lush-er, but it is in a pretty small container. You didn't say if your containers are in full sun and what kind of weather you've been having, but I'd start by repotting into bigger pot.

[HappyValleyGarden]

I'm sorry It was a long post because it seemed like all of the problems might be related. I'll break it into separate posts, embed the images correctly, and try again.

Sorry.

[rainbowgardener]

No apologies needed. I was just trying to give some suggestions how you might attract more answers for your questions...