Yesterday, April 12, 2011, we finally had degree days! 6.6 per our Chippers weather station, and it was probably over 10 at lower elevations.

Growing degree days are used to predict the hatch/vulnerability of insects – in our case on woody plants. They are calculated by taking the high and low (in Fahrenheit) of each day, taking their average, and deducting 50. Negative numbers are thrown out, as happens all winter.

Insects that make an early appearance are White pine weevil (mostly a problem for spruce) and pear thrip (a problem for Sugar maples).

Today, April 13th, we had a GDD of 7.3 today. Some of what you will see up to GDD 50: Red maple, magnolia, some rhododendron, pieris and forsythia will all bloom. White pine weevil may be seen doing its dirty deeds at 60 degrees and above, and we are treating for these this week.

These insects are all vulnerable to dormant oil spray up until gdd 50: Scales, Aphids, Mealybugs, Psyllids, Aphids + Mites.

For more information on this topic, please visit our website, www.chippersinc.com.