Agronomic Tools and Resources | Growing Degree Days (GDD)
What are Growing Degree Days (GDD) and Why Use it. Purdue University’s explains GDD as being used to estimate the growth and development of plants and insects during the growing season. Plants and insects will start growing and developing only when the average daily temperatures hit the minimum development thresholds. An example from Purdue University, when the average daily temperatures reach 50 degrees Fahrenheit, sweet corn, soybeans, and tomatoes will start growing. This means that the BASE temperature for these crops is 50 degrees F. Yield damaging insects such as European Corn Borer (ECB) also have a BASE temperature of 50 degrees F. Once you have identified the BASE temperature for the insects and crops you are interested in you can use NEWA to calculate and track the Growing Degree Days (GDD). Click here to watch a two-minute tutorial on how to navigate NEWA GDD calculator. Cornell University also has a great GDD calculato.
Why use GDD? A calendar is often used to predict planting dates and when to manage insects. However, with climate change, relying only on a calendar could be misleading. PennState Extension explains that research has shown that utilizing GDD provides a more accurate estimate of crop, insects, and disease development than calendar days alone.