Growing Degree Days
July 31, 2008
by Leo Lubke
We continue to see a significant rise in the Accumulated Growing Degree Days (AGDD) for this season. Generally, the Growing Degree Days range from the mid- to upper 20’s each day. Our AGDD, as of July 31, 2008, totals 2,346.6. We are now more than half way through the growing season, or 52%, when we look at Growing Degree Days as a way that many pests and perennials develop.
As you scan down the list of pests in the “Using Growing Degree-Days for Insect Pest Management”, you will begin observing a decline in the types of pests. (Of course, Aphids (nymphs and adults) “never seem to give up”; they’ll be around until about 2,800 AGDD!) A few others will “come and go”, but the majority have completed their life cycle until next year.
Use this concept in planning a fall garden. Not only will the weather be cooler for garden work, but also many pests have vacated your landscape and garden area. When following the Integrated Pest Management (IPM) approach of using pesticides only when needed, fall gardens produce more crops with less chemical use. Simply put, chemicals are not necessary since pests are not as prevalent.
Still another IPM suggestion relates to Growing Degree Days. While many pests are not present in their destructive stage in late summer or fall, they may still be present in a non-destructive stage next season. Eggs and larva, as an example, may be found in garden litter. When “the time is right” (i.e., AGDD promotes the pest development), the next pest stage moves from the garden debris onto your plants and begins feeding. Practice good garden hygiene AND rotate your crops to break this cycle.
By coupling the concept of Growing Degree Days AND Integrated Pest Management, you will be growing healthy crops that are safer for the environment. AND – there’s nothing more pleasing than having fall grown vegetables on the Thanksgiving and Christmas dinner table!
As a side comment my weather station here in Kodak reports 3.19 inches of rain for July and 20.21 inches for 2008 to date.
Remember that if you need the Growing Degree Chart for your reference, or have questions, please contact Alan or Leo.