Cucumber drying up and gnats in tomatoes…need advice!

Cucumber drying up and gnats in tomatoes…need advice!

My cucumber plant has developed drying vines. This is recent, since I pulled out a huge squash plant that was taking over everything. I'm still getting good cukes on the healthy vines, but I'm concerned that I might have a disease. It also could be too much sun and heat (?) since removing the squash, which was providing some shade. The timing is suspect. Everything else in the garden seems to be fine, other than an ongoing problem with gnats getting into splits that develop on some of the tomatoes. That's nasty, but I've got enough tomatoes to make up for the gnatty ones. I'm mostly concerned about the cucumber plant. Any thoughts, experience? I should mention I'm in zone 6 (St Louis) and it's been hotter than hell (upper 90s nearly every day, had a week of 100+ and high humidity), plus we're in a major drought. I do water daily. Thanks if anyone might have ideas.
my humble abode

my humble abode

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Oh no…are these aphids?

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First bloom of the year :)

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Almost frost

Plumerias; Shiitake Mushrooms

Plumerias; Shiitake Mushrooms

Oh noes! Garden pests!

Oh noes! Garden pests!