Hey there! I have yet another gardening question.
This is my first year working on a full sized veggie garden in pots on my back deck. For a while everything seemed okay, but now all the bad stuff is setting in; my lettuce is turning yellow before it's fully grown, and my squash and cucumbers are turning brown on the tips- yuck!
I'm not too worried about the lettuce, but what's happening to my squash? I had so many and now they're turning yucky. Anyone know what kinds of diseases occur in squash?
I agree with mudster that you're probably seeing un- or under-pollinated fruits. The female flowers have little baby fruits behind them, but if they're aren't pollinated, they'll just fall off or rot. If they're underpollinated, they may develop, but not evenly. Here's a site with a picture of underpollinated squash. I often see mine with one fat end and one skinny end too.
You can play pollinator yourself by taking a male flower (has a long stem and no baby squash swelling behind it) and using a paintbrush to pollinated the female flowers. Or just wait for the bees to get going.
Or are these fully mature squash that are rotting on the ends?
Blossom end rot will only affect cucurbits that have been pollinated. Since it's so early in the season, I think the more likely problem is that your fruit isn't getting pollinated, so the female blossoms (the ones with the little fruit) are just falling off. This is totally normal and will taper off later on, once you have both male and female flowers blooming at the same time.
I looked at your profile and see that you live in NC. I live in AZ so may not have equal experiences because of climate differences.
Heat stresses lettuce as it is a cool season crop. I couldn't even think of growing it now. Has your summer heat begun?
There are squash borers which can be responsible for crop failure. Looking at the stems, you may see holes where the bugs enter to begin their damage. Cut this off, behind the place of entry and destroy the infected parts.
What soil is in your pots? Is it possible that you could have a fungal infection? I have had a powdery mildew on the leaves when there is a lot of humidity but that doesn't seem to affect productivity and is only ugly.
Have you tried your local garden center? (not the Big Box stores, but a real garden center) Is there a local ag extension service in your area? I've found them to be of enormous help with gardening questions.