GDD update April 1

Some areas of the state are already in the GDD ‘zone’ for our earliest pests.  Others are still at 0 GDD.  Where are you?  Check out NEWA to find your nearest weather stations and their GDD – base 50 starting March 1.

Here’s the update (more or less) I sent out today.

Get ready to treat for :

White pine weevils – adults 7-58 GDD (soil on warmer side of tree 2” deep should be 50F) if you see adults or drops of sap on leaders – on pine and spruce but can be on Douglas fir and fir


Spruce spider mites – oil for dormant spray about 7- 50 GDD – on fir, spruce, pine, Douglas fir


Pales weevils – treat stumps less than 2 years old to prevent egg laying on fir, pine and spruce


Phenological indicator – silver maple, Cornus mas (Cornellian cherry)


The forecast for the next few days is for no additional accumulation of GDD but things can start changing fast.


Keep scouting for:

 Balsam twig aphid – eggs hatch about GDD 30 – especially on species with early bud break – best control is after egg hatch and before bud break.


Cooley spruce gall adelgid on both Doug fir and spruce – nymphs start to be found around 22 GDD and you need to treat before they wax over


Spruce spider mite – eggs start hatching at 50 GDD, Do you know the residual period for the pesticides you use?  That is another piece of information that can help you determine when you need to apply it, within the GDD range, if your scouting records show you need to use it.


Now that you have the first information – is this still a good weather station for your farm?   Let me know if you want to change or add stations at any time.


If you have time, let me know what’s blooming near you.  Cornus mas (Cornellian cherry) is out here in Ithaca and we are about at 6 GDD.