Which fumigants are commonly used during spot fumigations?

The use of phosphine, aluminum and magnesium phosphides, and sulfuryl fluoride is predominant in spot fumigations because these fumigants are effective at controlling pests in targeted areas, rather than broad applications. Phosphine and its related compounds are particularly valuable due to their efficacy against stored product pests and ease of use in confined spaces, making them ideal for localized treatment. Sulfuryl fluoride is another versatile fumigant commonly employed in situations where a quick and effective solution is needed for infestations, especially in structures or commodities.

In contrast, the other options include various gases that are either less suitable for spot fumigation or are used in broader applications. For instance, carbon dioxide and ozone are not primarily used for controlling pests but have other roles in environmental management and sterilization processes. Methyl bromide and chlorine, while effective, are subject to stricter regulatory controls and are less commonly used in spot treatments due to their environmental impacts. Ethylene oxide and hydrogen cyanide are also largely restricted based on safety and health concerns, limiting their practicality for routine spot fumigation compared to the agents in the correct answer.