Which method of pest control is primarily preventive rather than curative?

The choice of using protectant fungicides emphasizes a preventive approach to pest control, specifically targeting fungal diseases before they take hold. Protectant fungicides create a barrier on the plant surface, which helps to inhibit fungal spore germination and subsequent infection. This proactive method ensures that potential threats are mitigated before they can cause damage, aligning with the goal of prevention rather than addressing issues after they arise.

In contrast, the other mentioned methods tend to address existing problems or offer only reactive measures. Systemic approaches involve the application of substances that are absorbed by plants and target pests after they have infested the area. Similarly, residual insecticides work to eliminate pests present in an environment rather than preventing them from entering. Contact insecticides act directly when insects come into contact with the chemical, which may offer immediate relief but does not inherently prevent future infestations. Therefore, opting for protectant fungicides aligns with a strategy focused on preventing pest issues before they develop.