What is true about dormant oil that has higher viscosity?

Higher viscosity dormant oils are typically formulated to be thicker and have different physical properties compared to lower viscosity oils. One of the key characteristics of higher viscosity oils is their potential for increased phytotoxicity. Phytotoxicity refers to the potential of a substance to cause damage to plants. Thicker oils can adhere more strongly to plant surfaces, which could lead to greater absorption into plant tissues but also result in potential damage if not applied correctly.

In the context of integrated pest management, the trade-off with using higher viscosity oils involves careful consideration of their application. While they may provide better coverage and longer residual effects, this increased thickness can also increase the risk of causing harm to the plant if environmental conditions are not optimal or if the oil is applied in excess.

In contrast, options suggesting longer absorption times or reduced effectiveness do not accurately characterize the properties of higher viscosity oils. They do not inherently take longer to absorb; rather, their adherence properties may lead to increased risks of phytotoxic effects. Therefore, higher viscosity oils can indeed be associated with higher phytotoxicity, making that choice the correct and informative answer.