Which is a disadvantage of both EC and ULV formulations?

The chosen answer is correct because one of the primary concerns with emulsifiable concentrate (EC) and ultra-low volume (ULV) formulations is their solvent content. These solvents are necessary for dissolving the active ingredients in the formulations, but they can also react negatively with certain materials used in application equipment. Specifically, rubber and plastic components, such as hoses, gaskets, and pump parts, can deteriorate or degrade when exposed to these solvents over time. This deterioration can lead to equipment failure, leaks, and inefficiencies in the application process, which jeopardizes both safety and effectiveness.

In regard to the other options: while constant agitation is important for maintaining suspension in EC formulations, it is not a disadvantage shared with ULV formulations, as they typically require less agitation. Difficulties in handling, transport, and storage may apply to some formulations, but considering the specific context of EC and ULV types, they are often designed for easier application and storage as long as proper protocols are followed. Lastly, while abrasive wear can be an issue with certain formulations, it is not a direct disadvantage commonly associated with both EC and ULV formulations specifically compared to other types.