Under what conditions can a pesticide be used in California agriculture?

A pesticide can be used in California agriculture only if it is registered and labeled appropriately. This requirement ensures that the pesticide has undergone rigorous evaluation for efficacy and safety under the California Department of Pesticide Regulation (DPR). The registration process includes a thorough examination of the pesticide's active ingredients, its potential environmental impacts, and its effects on human health and non-target organisms.

The labeling is crucial as it provides essential information on how to safely and effectively use the pesticide, including application rates, safety precautions, and any restrictions that may apply. This helps to ensure that users are applying the pesticide in accordance with state regulations and using it in a manner that minimizes risks to public health and the environment.

In contrast, conditions like affordability, local purchasing, or historical usage approval do not ensure safety or effectiveness and do not meet the rigorous regulatory standards that pesticides must adhere to in California agriculture. Hence, the correct answer highlights the importance of proper registration and labeling as the primary conditions for pesticide use in the state.