Resistance to herbicides in a plant population is typically detected after what percentage of resistant biotypes has spread?

Resistance to herbicides in a plant population is typically detected once around 30% or more of the biotypes exhibit resistance. This threshold reflects a significant enough presence of resistant individuals that it impacts the overall effectiveness of the herbicide on the population. When 30% of a population is resistant, it often becomes evident that the conventional control methods are failing, leading to increased attention and concern regarding herbicide efficacy.

This level of resistance indicates that the genetics of the plant population has started shifting, allowing for survival and reproduction of resistant types, thus making it essential for professionals in aquatic weed control to adapt their management strategies. Recognizing the presence of resistance helps in implementing more sustainable practices and reducing the continued selection pressure that contributes to further resistance development.