Different GDD models can be utilized to monitor insects, weed development, seedhead emergence, and other targets. By creating individually named alerts, you can customize thresholds for different targets and easily identify when a threshold is reached for a specific target. Thresholds can be created to include individual plants, pests or locations. For example: "Annual Bluegrass Weevil" or "Poa annua."

Base temperatures used in calculating GDD vary depending on the type of plant or pest that is being monitored. This number represents the temperature at which you will typically begin to see plant or pest growth². The base temperature most often used in calculations is 50°F (10°C), because it is the temperature when active growth begins for most organisms³. However, some plants or pests can thrive in cooler environments, and in that case, growth should be measured using the base temperature of 32°F (0°C). For more information on which base temperature best suits your turf management plan, please contact your local extension service or Syngenta territory manager.

²United States Golf Association "Getting a Handle on Nature's Clock" 2013.
³United States Golf Association "Getting a Handle on Nature's Clock" 2013.

The threshold number is the target number of GDDs that you wish to accumulate based on the GDD model you are using. By tracking the number of GDDs, you are able to better monitor the developmental stages of the plant or pest. Once the accumulated GDDs reach 90% of the target threshold you have selected, you will receive a reminder email alert. This pre-notification is designed to give you advance warning that your threshold is nearly reached and to be prepared to take action based on your target organism. You will also receive an alert once you reach 100% of your target threshold.

For assistance in selecting the best target threshold number for your turf management plan, please contact your local extension service or Syngenta territory manager.