That is powdery mildew on your squash plants. If the soil is bone dry while the pepper plant is wilting yes it is under-watering. But the same wilting affect can be the result of other problems including over-watering.

The tomatoes drying up and dieing sounds like wilt, and this has been a bad year for it here on Long Island. Too much rain/moisture makes it worse, and the black spotting on your peppers sounds like a bacteria, which also is helped by too much moisture. Nsxt year, you might want to plant wilt resistant varieties, rotate your planting, and use a thick organic mulch to regulate the moisture and prevent weeds. Blessings, Ron http://www.TheGardenGuy.org

Hey there, Sorry for the late late response, cant seem to figure out how to get the email alerts for replies to my messages...Hmmmm....I just upload my images to the site "Photobucket.com" and post the link for people to copy n paste into their address bar =/ works unless there are tons of photos to post, lol. I did the same and they're turning out alright, glad you figured it out too! Only problem are the slugs n snails, and the chickens, but thats a whole other story... I just got done spreading chili pepper powder around my few tomato plants to keep the slugs n snails off of them, seems to have worked so far, but its going to be a constant battle Im sure. Between killing them myself, all the toads and chickens around here(they both love the slugs), and the chili powder, I think I have them beat..for now. I grow pretty much anything I can find actually! I have some venus flytraps, the tomatoes, strawberries, a small bonsai or two, a bunch of shell and vertical ginger, 3 or 4 kinds of cannas(Indian Shot(red orange and yellow versions) and large Canna Lillies, Cooks Pine, hibiscus of all kinds, trying to find more contantly, working on different color plumeria trimmings, mountain apples, a few different ferns(Staghorns, Luau, working on Tree ferns, etc.) heliconia of all kinds, have the red and yellow hanging, a few vertical species, pink, orange, etc. Im pretty much just gathering all that I can, lol! We have yardsales up here in the wailua homesteads, and I put the plants out all the time, in the last 6 weeks Ive made about 180 or so in plants alone XD People really like the ginger and stuff, I put good plants out super cheap, do it mostly just to fund my gathering, lol. Im working on Tahitian Jasmine and Gardenia cuttings right now, have about 10 or so of each, and will be trading some with the neighbor for some various rose cuttings. Constantly gathering orchids, though I only have about 4 kinds, could get expensive if I decide to go all out =p If you're on Kauai n are interested in any of it, lemme know either on here or email me, and we can do some trades or something, take it light til I talk to ya next! Aloha, ~Dave P.S. If anyone reads this, Im looking for the following plants, trimmings/rhizomes preferred if not an already started one; Puakenikeni, ANY Heliconia or Cannas, Wild Plantain, any color, have yet to obtain some! and pretty much any other interesting plants, lemme know what you have and Ill let ya know what I currently have, we can throw up a trade or Ill just buy a few trimmings if not crazy expensive! =p Mahalo!

A local horticulturalist thought it might be too early for much of a 'pest' issue since it is pretty cold at night in the area. It has been in the low 30s two nights in a row several days ago. The plants were just potted from purchase from a nursery. The nursery also thought it might be sunscalding. Either way I'm spraying with Neem Oil, supposedly good treatment and preventative measure for this, and going to try rehardening them again. Thanks for the input, much appreciated!!