Wider spacing in beds and landscape plantings promotes rapid drying after wet periods and stops development of foliage, flower and fruit pathogens. Avoid excessive soil moisture. Overwatering enhances seed decay, damping-off and root rot diseases. Try not to plant in areas that have poor drainage or where water stands for several days following rains. In other words, use good cultural management.
Healthy plants are less likely to have disease problems than weak, undernourished ones.
Grow plants under optimum conditions and there will be fewer disease problems. Control of most plant diseases can be accomplished without pesticides. Use sound cultural practices, sanitation and well-adapted plant varieties to reduce disease problems. It is important to realize that you must accept some disease loss. Don't expect a perfect Garden or plant if you do not want to use chemicals.