What are "growing degree days" (GDD) used to predict?

Growing degree days (GDD) are a measure used to predict the development rates of plants and insects based on temperature. This concept is rooted in the fact that biological processes, such as germination and maturation, are influenced by temperature accumulation.

GDD is calculated by assessing the daily temperatures in relation to a base temperature, which is the minimum temperature that allows the growth of a specific crop or insect. By accumulating these degree days over the growing season, farmers and agronomists can estimate when certain growth stages will occur, enabling them to plan for activities like planting, fertilization, and pest control at the optimal times.

This understanding is crucial in maximizing crop yield and managing pests effectively, thus making GDD a valuable tool in agricultural management. In contrast, while factors like soil nutrient levels, weather patterns, and crop harvesting times might relate indirectly to the impacts of temperature, they do not directly reflect the biological growth processes that GDD specifically measures.