Which is an example of a physical barrier used in pest management?

A physical barrier is a tangible method that prevents pests from accessing plants or crops. Row covers or nets effectively shield plants from various insects, thereby reducing the risk of infestations without the use of chemical treatments. These barriers can be made from lightweight, permeable materials that allow light, air, and moisture to reach the plants while keeping harmful pests away.

The other options involve different pest management strategies that do not qualify as physical barriers. Spraying insecticides and using pesticides target active pest populations but rely on chemical control methods rather than a physical separation between pests and plants. Meanwhile, rotating different crops in a field is an integrated pest management strategy aimed at disrupting pest life cycles through crop diversity, but it does not involve a physical barrier to prevent pest access.