Try to maintain an even water supply and avoid dry-wet fluctuations. Avoid watering late in the day since this will favor disease conditions. Remember that too much moisture will favor several root and foliage diseases. When watering with a hose, try to wet the soil, not the plants. Control weeds in and near the garden.
Weeds help create a micro-climate that is ideal for development of fungus and bacterial diseases.
They may also provide the initial source for certain virus diseases. Control insect pests. They may carry and spread certain virus and bacterial diseases. Destroy diseased plants as soon as you observe them in your garden. Otherwise, they may serve as a source of spread to other plants.