April 15, 2019

April 15 GDD update

The range of GDD for the group of growers in this project is from 4-67 – so you can see the variation by location!  And I expect things will start moving fast soon!


A reminder that insects don’t read books (or my emails) so scouting is always the best way to determine if an insect is present and at what developmental stage.  The GDD ranges give a suggested window for scouting.

Balsam twig aphid management 30-100

Cooley spruce gall adelgid management 22-81

White pine weevil management 7-58 GDD – a few areas have hit this deadline already and more will by April 20.  You might still catch Eastern pine weevils in the traps after 58 GDD and they are hard to distinguish from white pine weevil.


So many pesticide applications state ‘treat before/or after budbreak’.  I understand budbreak on a single bud – when the bud scales open and you can see the new needles inside.  But what about budbreak on a field basis – especially if you have different species or cultivars in the same species?  Just looking at some research papers, I found budbreak defined as:

  • The day when buds in the upper 1/3 of the crown showed green needles under the cap of the bud scales
  • Once one shoot broke its bud scale


Those are pretty different measurements.  So when would you treat for needlecasts, for example, as you are trying to protect new foliage – after budbreak?  Brian’s research on Swiss needlecast on Doug fir is showing that you can get good control starting spraying later when there’s about an inch of new growth and you don’t have to guesstimate bud break.  For control of needlecasts good coverage is essential.  Have you ever tested your spray coverage?


Some insects are good at avoiding contact insecticide applications.  Anything that forms a gall or feeds inside plant stems and those that have scale or waxy filament coverings are essentially wearing pesticide raincoats.  That’s why you need to apply the insecticide at their weakest development stage – before they get under cover.



Have a great week!

April 15, 2019

April 10 Christmas tree update

Anyone seeing bud break yet?  I need to check my (few) trees.


Cooley spruce gall adelgid management is best between nymphs appearing (around 22 GDD) and bud break

Balsam twig aphid management is best between egg hatch (starts around 30 GDD) and bud break

Time for Doug fir needle midge traps (before daily temps are 60 F on N side of previously infested trees) or yellow sticky cards to catch adult midges


I was going to write an email on horticultural oil applications, but Jen Llewellyn did it for me!




Dormant oil can be used to manage:

Spider mites and eriophyid/rust/sheath mites

Cooley spruce gall adelgid

Elongate hemlock scale

Balsam twig aphid

Cryptomeria scale


Remember that Doug fir and spruce can be sensitive and oils will take off the blue coloring of needles



Have a great week!

April 1, 2019

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. http://newa.cornell.edu/

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.


March 11, 2019

Insect and disease update for Christmas trees – March 11, 2019

As part of a grant with NY Farm Viability Institute, I am putting insect models based on Growing Degree Days (GDD) into NEWA.  As part of a trial, I am working with growers to see if using GDD helps provide better control with fewer pesticides used.


Today’s message:

No accumulated growing degree days yet in NYS, which is why you are all getting the same message!


Riverhead is getting close to its first one!  Remember, the average temperature needs to be over 50F and the accumulation started March 1.


Here are a few things you can do or get ready:

  1. Get your traps ready
    1. Tedder’s trap for white pine weevil https://ento.psu.edu/extension/christmas-trees/information/whitepinewvtraps.pdf
    2. Doug fir needle midge trap https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1373.pdf
    3. Yellow sticky cards for
  2. Remove or treat stumps and remove cull piles and dying trees before adults emerge (starting about 7 GDD) for Pales weevil and Eastern pine weevil management
  3. Scout – starting with trees that were affected last year
    1. Spruce and rust mites
    2. Cooley spruce gall adelgid nymphs on Douglas fir and spruce
    3. Swiss and Rhabdocline fruiting bodies on Douglas fir needles
    4. Rhizosphaera and spruce needle rust on spruce.


Have a great week!

January 2, 2019

Greenhouse IPM update 1.2.19 When is Sevin not Sevin?

I thought this was an interesting post.



Pesticide use is becoming even more complicated.  Note that Sevin no longer contains carbaryl.  This article from Texas A&M AgriLife Extension explains the situation.

I photographed the previous and new product bottles and labels.  The bottle on the left is the previous product that contains carbaryl (100 on label) and the one on the right is the new product (500 on label).  These are completely different active ingredients, both called Sevin.

Please remind your clientele to “Read the Label” when using pesticides!




Dr. Norman C. Leppla, BCE




December 21, 2018

Christmas tree IPM update 12.21.18

Sounds like it has been a good year for most (at least those people who have told me) so I hope everyone is basking in that glow – or will be as soon as they can close!


Just to get you ready for January…. In addition to the CTFANY meetings all over the state (dates and locations below – more information soon), Michigan State is sponsoring a series of webinars on ‘What’s New in Christmas Tree Production’


January 30         Effective Nitrogen Use

February 6        Quarantine Pest Issues – Elongated hemlock scale and spotted lanternfly                     

February 13      Evaluating the performance of Turkish and Trojan Fir (CoFirGE)                   

February 20      Reducing coning in Fraser fir

February 27     Choosing Cover Crops    


CTFANY meetings  

Jan 17    Syracuse

Jan 24   RiverheadJan 30               Hudson Falls

Jan 31   Millbrook

Feb 7     Hammondsport

Feb 13   Batavia

Have a restful holiday