GDD update 8.30.19

Another lovely day! I seem to be sitting here contemplating life and IPM conundrums.

How do you deal with control measures that you can’t do at the ‘right’ time?  Sometimes it makes a difference and sometimes you just need to know a bit more about the insect. For example, if we are talking about a scale insect that has a particular GDD range for crawlers, applying the appropriate pesticide must be done while the crawlers are out from under their mothers’ scale covers and before they form their own protective coatings or it is wasted.  What about removing trees with balsam woolly adelgid?  We recommend doing it in the winter so that the beasts are not active and maybe will stay put on the affected tree, or croak if they fall off.  Regardless, we worry about spreading them to surrounding trees so tarping any trees you are taking out or burning them in place, if allowed, makes sense.  So it can be done at any time – just be very careful.  Consider spraying any trees around them and along the route where you removed them.  This particular adelgid is too small to readily see.


What about things that look the same?  Cooley spruce gall adelgid and Doug fir needle midge – both on Doug fir. Yellowing and kinking of needles for both so you might need to do a little more sleuthing. The adelgid is forming a gall – albeit very small – so you might find a larva in the swelling on the needle.  Cooley’s has fluffy white egg masses in the spring on Doug fir.  Do you remember seeing that? (Insert plug for keeping good records here!).  They are different types of critters and treatment is not necessarily the same so good id is important!


And what’s brewing in bugland?


Nothing new – but they are all still out there for the scouting!


Spruce spider mite – 2375- 2806 GDD

Doug fir needle midge – remove heavily infested trees (carefully so you don’t spread the pest) before larvae exit the needles (needles will turn brown). Mark infested trees for placing traps in the spring


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