Which of the following is NOT a basic control approach to aquatic weeds?

Physical control is an important method used in managing aquatic weeds and involves the manual removal or mechanical disruption of unwanted plants. Techniques in this category can include cutting, harvesting, or using machinery to remove plants from the water.

The other control approaches mentioned—preventative control, cultural control, and chemical control—are all fundamental strategies in managing aquatic weed populations. Preventative control focuses on stopping weeds from establishing in the first place, such as through education and habitat modification. Cultural control involves changing practices to make the environment less conducive to weed growth, such as altering water levels or planting beneficial plant species. Chemical control employs herbicides to target and eliminate weeds.

Thus, physical control is very much a basic approach to aquatic weed management, while the other listed methods represent significant strategies in the broader context of integrated pest management.