June 14, 2019

GDD update 6.14.19

Inching up there – although today probably isn’t adding much!

Things to be looking for:

‘Shepherd’s crook’ wilted leaders on spruce, pine, Doug fir – occasionally fir – are caused by white pine weevil.  Cut them out and destroy the leaders before July (even this year!) to prevent adults emerging.  Prune down to healthy green wood.

Another note on white pine weevil – 2-5% of trees damaged this season is the threshold (in forestry) for treating next season.

Hey, they don’t read the books! Spruce spider mite should be a cool season mite but according to Branching Out they are being found in high numbers even in warmer seasons, so keep scouting if you’ve had them before – especially spruce.  Tap tests – and when you smear them on paper, they leave a green streak (from all the chlorophyll they have been sucking out of your plants)


And keep scouting for cryptomeria scale even after 700 GDD.  Spray recommendations from PA suggest continuing management beyond that point if you find crawlers.



Two spotted spider mite – 363-618 GDD

Cryptomeria scale crawlers – 600-800 GDD

Elongate hemlock scale crawlers – 360-700 GDD

Gypsy moth larvae – 90-448 GDD

Douglas fir needle midge adults –  200-400 GDD

Pine needle scale crawlers – 298-448

Striped pine needle scale crawlers – 400-500

Introduced and red-headed pine sawfly larvae – 400-600


Have a great week!


March 22, 2016

Christmas Tree IPM Update 3.22.16

Just a little snow fell at my house yesterday but it still feels springy!

And that leads us directly into the first question I received this spring:  When should I treat for white pine weevil?  Now (although maybe a slightly warmer day than today) urging by the Cornus maas blooming outside my office window and the silver maple I saw blooming in Geneva last week.  7-58 growing degree days.  You are trying to control the adults before they lay eggs and you know how a young white pine weevil’s fancy turns to love in the early spring.  Target the top third of the plant where they hang out.

Brian’s blog post on wpw:
For more pictures:
Do you get Sarah Pickel’s PA Christmas tree IPM report?  A good way to see what is heading our way.  Contact her at: c-sapickel@pa.gov
Sarah Pickel | IPM Education Specialist
PA Department of Agriculture | Bureau of Plant Industry
2301 North Cameron Street | Harrisburg, PA 17110
P: 717-772-5227

What is she seeing besides white pine weevil?
Pales weevil – larger than White pine weevil and with different habits.  While mostly a pine problem, the adults will feed on the bark of other conifers resulting in flagged or dead branches.  Eggs and larvae are only found in newly cut (less than a year) pine stumps so chipping or removing pine stumps is a good management practice.

Eriophyid mites – just starting.  These mites are tiny so it takes close scouting.  They can be carrot shaped or more elongated.  The eggs may be in clusters on the bottom of the needles.  Just a bit larger than the stomata spots.  There is a threshold for this pest – 80% of twigs with mites and at least 8 mites on a single needle on one shoot.  Get your hand lenses out!
Are you out in the trees yet?  I bet you are on the warm days.  Seems appealing when I am in my office.  I did walk my  conifer plantation the other day, though!  Lost one but the other 8 are happy.  🙂

Have a great week!

March 22, 2016

Christmas Tree IPM Update 3.9.16

Coming out of hibernation?  No, coming out of education season so I am actually in my office all week.  Winter aconite and snowdrops at my house and crocuses at Cornell!

Woo Hoo!  The new 2016 Cornell Pest Management Guide for Commercial Production and Maintenance of Trees and Shrubs (we don’t mind if you call it the Cornell guidelines for trees and shrubs) is out! Hard copies are available from the Cornell Bookstore in the next couple of days.   Have a photo that you think is cover-worthy?  Send it along and if it is chosen for next year, we’ll credit you (and I’ll send you a free copy of the 2017 guidelines!)

A (very small) shout-out for deer!  What?  Well, they don’t spread Lyme disease, although they do spread ticks.  Ticks can pick up the disease organism from mice, chipmunks, voles, etc. though, and they are out NOW.

Warm spring, early white pine weevil?  I expect so.  7-58 GDD (don’t know what that means?  Shoot me an email!) And one place to get your GDD is NEWA.

A couple of growers have told me that they are trying Tedders’ traps to monitor for white pine weevil.  I hope they keep me posted and I’ll keep you posted. Information on how to build your own – or buy them (there may be other sources, this one seems to pop up)

Enjoy the weather and have a great week!