GDD update 8.13.19

I think this is the first time I have done the reading 5 days apart – which it how far out the prediction goes.  The predictions are remarkably good.  Most are no more than 10 points out (max was 20) and only one was lower than predicted by a few points.


Check out some other tools. The Climate Smart Farming GDD calculator lets you put in your address or click on the map for a location. I’m not sure where they get their data from and how it is calculated to a specific site.  My house in Ithaca is almost 100 GDD points lower than the campus location – but that is probably correct.  You can also put in several locations and compare them.


It is aimed more at crop development – for example, you can put in a planting date and the GDD Base that is the default is 50/86 as it is based on the fact that crops don’t develop much under 50 F and over 86 F.  You can choose other bases


By comparison, in the NEWA system we’ve been using I selected a March 1 start date, not because of planting but because we usually don’t have much insect development before that and the GDD accumulated in a spring thaw throws things off a bit.  Also, we use the GDD base of 50F with no upper limit – which isn’t perfect at very high temperatures, either.


The CSF system lets you put in a GDD target – for example, if you knew the second generation of spruce spider mites is expected to start at GDD 2375, you could put in a target of 2200 to give yourself some leeway and it will indicate for each site >2 weeks to target, <2 weeks to target or target has been reached.


Try it out!


There are several other tools under the Tools tab. An interesting one tells you climate change for your county since 1950 with a variety of different measures.



A few new things to add:


Spruce spider mite – 2375- 2806 GDD (notice how I worked that in above 😊 ) – for a few of you on Long Island

Doug fir needle midge – remove heavily infested trees (carefully so you don’t spread the pest) before larvae exit the needles (needles will turn


Mark infested trees for placing traps in the spring


And the others just keep rolling on:


Elongate hemlock scale – keep scouting for crawlers.

Cooley spruce gall adelgid – prune out galls on spruce before they turn brown (about 1850)

Cryptomeria scale crawlers – 1750-2130 GDD

Japanese beetle adults – 1029-2154 GDD

Two spotted spider mites– 1300-2000 GDD

Pine needle scale 2nd generation– 1290-1917 GDD


Have a great week!