What is the threshold of grubs per square foot that may not cause noticeable damage with good irrigation and fertilizer?

The threshold of 20 grubs per square foot is recognized as the level at which they may not cause noticeable damage, particularly when good irrigation and fertilizer practices are in place. This threshold is based on research that indicates a balanced lawn care regimen can mitigate the impact of these pests. When grubs are present in moderate numbers and combined with healthy turf management practices, the grass can often withstand the feeding activities of these larvae without showing significant signs of stress or damage.

Grubs feed on the roots of grass, and while higher populations can lead to harmful effects, maintaining proper lawn care — including adequate watering and fertilization — helps promote root growth and resilience. This means that at a population level of 20 grubs per square foot, the lawn may be robust enough to tolerate the feeding without showing visible symptoms like wilting, discoloration, or dieback.

Understanding this threshold is crucial for pest management and making informed decisions about when intervention might be necessary. Recognizing that not every instance of grub presence requires immediate action allows for more sustainable pest management practices.