I am a plant hypochondriac

I am pretty bad at self-diagnosing myself using the various online resources. It turns out, I'm the same when it comes to plants. Fortunately, with the peas, granny told me the leaves look healthy (thanks!). Now I found some sketchy looking brown spots on my zucchini plants. After searching around on the inter-web, I found some pictures that look similar but no concrete answers. I'm thinking it is either sun/wind burn or something fungal. The leaves feel really dry (though the soil has enough water). I'm seeing some fungal gnats too, so probably I need to decrease the watering. I have 2 zucchini plants in a smaller pot living on the ground floor (under the balcony). The ground floor plants are the seedlings that I was thinking of putting in the compost bucket but couldn't bring myself to do it. Anyway, the ground floor zucchini, despite being in a smaller pot, don't have this problem. The difference between the 2 plants are that they are not in direct sunlight throughout the day and they are not a self-watering pot so the water just drains out the holes on the bottom. (oh, and all my plants - not the seedlings - spent the weekend outside).

Zucchini plant in the larger pot, the edges are brown and drying

The other zucchini plant on the balcony, the dry patches in the center is browning - not powedery

Zucchini plants on the ground both look healthy

Many years ago I watched a show with Jamie Oliver where he was trying to promote healthy eating for children. He was working with a group of grade school kids (I want to say about 5th grade) where he would show them a vegetable and asked if the kids knew what the vegetable was. I distinctly remember that the kids could not identify celery. It is pretty amazing that there are kids out there that don't know what fruits and vegetables look like let alone how they grow. To this end, my knowledge of how vegetables grow and what they look like before they are mature is limited. For example, I didn't really think you can grow lettuce from seeds...I'm not sure how I thought they grew, but I just never thought about lettuce seeds. As a results, I've been fascinating by the mesclun green seedlings (they are starting to grow leaves that look like mescluns). Now I'm curiously observing the growth of the arugula seedlings. At this point they don't look anything like arugula, but if you taste them you can definitely tell they are arugula (a bit more bitter than I'm used to). If you compare the arugula seedlings versus the petunia seedlings (the ones that I collected last year, that I'm absolutely surprised is actually germinating), they pretty much look the same (and are about the same size...tiny).

Arugula seedlings

Some more arugula seedlings

These are petunia. Up close they look different but they are about the same size as the arugula seedlings

Speaking of petunias, I planted some in a container in the front of the house. I did the same last year and I had some serious problems with tobacco worms. They seem to only like my flowers since I was careful to examine the flowers of my neighbors and they had no damage. At least this year I have a bottle of Bt, ready for combat if necessary. It looks like at the moment I'm just having a little slug problems (I know only because I saw one the other night and I picked it off).  

You can see where the slug(s) feasted (white flower is half gone!)