In calculating degree days for codling moth how does one handle a negative day ?
Using Michaels formula , min. plus max. divide by two , subtract base of 50 . 42+56 = 98 divide by 2 = 49 - 50 = -1
Do I actually subtract from my total or does it just hold for the day ?

Hillview Heritage Farm
Zone 5*in British Columbia



Edited 1 time(s). Last edit at 03/19/2018 03:17AM by David Doncaster.

Hi David,

It will be counted as a Zero for that day. . . no subtractions, and no gain in the degree day count.

:-)

Gopher Hill Apples
Zone 8 in California

Thank you very much , sir .

Hillview Heritage Farm
Zone 5*in British Columbia

Hi David,
I recently discovered some digital tools that track GDD / GDU's. I can't recall if the tools' calculation process was transparent enough to help you track for specific pests & diseases (i.e., not sure if they say what temp level is used as a baseline). Still, it might be worth a look if you're into that sort of thing.

One was 'Agrible,' both an app and a website. Free basic tools, and you can pay extra for more. I found it handy.

The other was...ha! I can't recall. But pretty searchable on app stores.

Earthworks
Zone 7a in West-Central MD