Which soil condition would most likely cause phytotoxicity problems following a fumigant application?

• A. Cold and wet
• B. Cold and dry
• C. Hot and wet
• D. Hot and Dry

Answer: (A)

Phytotoxicity from fumigants is influenced by how soil temperature and moisture affect gas movement, persistence, and plant uptake. In cold, wet soils, the fumigant volatilizes slowly and tends to remain concentrated in the root zone, while the abundant water in the pores can dissolve and transport the chemical toward germinating seeds and young roots. This combination increases the amount of fumigant that plant tissues are exposed to, raising the chance of injury. In warmer or drier soils, the gas tends to move and dissipate more quickly, reducing the potential for high, localized concentrations near roots. So, cold and wet soil creates the conditions most likely to cause phytotoxicity after a fumigant application.