What type of irrigation method can contribute to bacterial and fungal growth?

Overhead irrigation can contribute to bacterial and fungal growth primarily due to the way water is applied to the plants. In this method, water is sprayed or sprinkled over the crops from above, resembling natural rainfall. This watering technique can create a moist environment not only on the soil surface but also on the foliage of the plants.

When leaves and stems remain wet for extended periods, it fosters an environment conducive to the growth of various pathogens, including bacteria and fungi. The moisture on plant surfaces can lead to diseases such as powdery mildew, downy mildew, and other fungal infections. Additionally, water droplets can act as carriers for pathogens, spreading them from one plant to another if the same equipment is used without proper cleaning.

In contrast, other methods like drip irrigation and subsurface irrigation apply water directly to the soil or root zone with minimal contact with plant foliage, significantly reducing the likelihood of creating conditions favorable for bacterial and fungal diseases. Surface irrigation, while it may also lead to some moisture on the surface, is generally less conducive to prolonged wetness on the plant itself compared to overhead methods.