Basically, he said the secret to vegetable gardening here is to know when to fold 'em and go fishing. Which is about now. Maintaining large tomato bushes now with no hope of fruit until early winter gives insects and disease an opportunity to flourish with not much to gain.
Fall gardens should start in late August or September. Another helpful suggestion is to plant resistant varieties. For tomatoes, Celebrity and Big Boy are root knot nematode resistant and enjoy good success. There are powdery mildew resistant varieties of cucumber and squash. For zucchini, try the Spineless Beauty varieties.
Thanks and happy gardening,