Final answer:
An efficient method to combat fungus gnats is allowing the topsoil to dry between watering and using crop rotation and pest-resistant plants. Fungal insecticides are preferred over chemical pesticides because they are environmentally friendly and align with organic farming practices. The correct option is A.
Step-by-step explanation:
An efficient way to treat fungus gnats is to turn over topsoil and allow the soil to dry to 1-2 inches between watering. This method disrupts the lifecycle of the fungus gnat by eliminating its moist breeding grounds. In terms of agricultural practices, this would fall under ecologically based control measures such as using pest-resistant cultivars and crop rotation to naturally reduce the presence of pests and improve overall soil fertility.
Using specific plants like neem, which has natural pest-repellent properties, can be part of an integrated pest management strategy. Fungal insecticides rightly serve as an attractive alternative to chemical pesticides for growing food crops.
Fungi can act as natural predators of harmful nematodes or compete with bacteria, reducing the need for toxic chemicals. Furthermore, these pest control methods are more in line with organic regulations, minimizing the impact on the environment by avoiding materials that can accumulate in the soil, such as copper, or cause health concerns like diatomaceous earth.