None of these plants do well in humid wet weather or with overhead irrigation.
I agree the beans,tomato and pepper all look like bacterial diseases or fungal. Anthrachnose, bacterial spot on the pepper. Beans could be bacterial or fusarium fungal disease
Zucchini and squash need pollination to make fruit. It may be inadequate pollination if they produced flowers. I switched to parthenocarpic zucchini recently to get better fruiting. Zucchini and squash are also very susceptible to fungal diseases like downy and powdery mildew
Since you have multiple fungal issues, you need to make sure sanitation is good. Pick up all the leaves and if plants are severely infected cull them or they will just become hosts to grow the problem.
Plant warm season vegetables when the weather is likely to be drier, and warmer. For me that is after the monsoon season.
If it is likely to rain and be very wet for days at a time. You will need to use a preventive fungicide every 3-5 days.
Make sure your plants are well spaced to allow for good air movement.
Choose varieties with resistance to disease. Most modern beans have been bred to be resistant to the common bean mosaic virus.
Beans = Provider, Jade,Nikel, Carson,Rocdor, or Espada.
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Corn Ilini Xtra Sweet, Murai, Silver Queen or Silver King, Ambrosia,Serendipity, Bodacious, Honey N' Pearl
Sometimes corn batches are not sweet, but the supersweets are usually good. If you get Golden Bantam, or regular corn they are more starchy and not as sweet.
Bell peppers in a hot humid environment does not last long. It is better to grow the Corno d'toro, Cubanelle, Banana, Shishito and other long sweet peppers instead. They are more productive and the plants are sturdier and more resistant to disease.
If you want to grow bell peppers the best will be California Wonder, Jupiter, Keystone, Yolo Wonder, Yellow Bell and if you order seed from Hawai, Kaala is a mini bell that was bred to be resistant and is the only bell that has lived more than a year for me. I don't like it because I don't like the small fruit.
The tomatoes are showing signs of Anthrachnose and angular leaf spot. Complete with the holes created when the necrotic areas drop out.
High humidity an alkaline soil that is probably fungal dominent. Sulfur the soil to bring the pH down to about pH 6.2 and make the soil less hospitable to them.
Watch your watering. I think you have a lot of compost in the soil so it is not drying very fast. You can have too much compost.
Mulch your plants to keep splashing to a minimum. Do not compost any diseased plants they need to go in the trash. Unless your compost is hot, it will not kill viruses or disease.
Since all of your plants are showing the same family of fungal diseases, there are a lot of spores in the air. In Summer, solarize the soil in the bed. In the meantime, plant the most disease resistant varieties you can find and use a fungicide like Serenade as a preventive. Corn can probably be planted spaced according to the label. You don't want to plant susceptible plants there to break the cycle. Grow tropical plants like yard long beans and NZ hot weather spinach. You need to select plant that have more resistance to disease and humid conditions. Remember there is often a tradeoff of some other trait for disease resistance.
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Happy gardening in Hawaii. Gardens are where people grow.