GDD update 9.11.20
I hope you all muddled on without an update last week. There is something about vacation that causes my mind to go blank and I forget what it is I do for a living. I’m slowly remembering!
Things will start to slow down now – but I expect we will get at least one more warm spell (I still have gardening to do!)
Sept 11 Sept 16
Champlain 2199 2239
Geneva 2463 2519
Riverhead 2635 2706
I had a question about what I think was balsam woolly adelgid. It is a sneaky pest as it is very small and tends to hide in the bark on trunks and branches so you might not notice it until you see the damage. It is one of those that finds a place to feed as a crawler, sticks its mouthparts in and never moves again (like me watching Netflix), covering itself in white woolly wax to protect itself and its eggs. I can say ‘herself’ because they are all female so no need to move to find a mate.
As she feeds, she injects a toxin and what you might notice first are nodes that look like arthritic knuckles – called gouting – although that can be somewhat inconspicuous sometimes (good pictures here:https://fpr.vermont.gov/sites/fpr/files/Forest_and_Forestry/Forest_Health/Library/VTFPR%20Forest%20Health%20Leaflet_Balsam%20Woolly%20Adelgid_2016.pdf)
The toxin also causes the wood to be brittle and can eventually kill the tree. On larger trees you might notice the tops are angled.
This insect is tiny and is spread by wind. It can also be spread on clothing/equipment so always work in any clean fields first and the infested ones last. If the trees are badly infested, you should remove them. But very carefully. Either burn in place or tarp if you are pulling them out of the field. Doing this in the winter when it is cold helps prevent the spread.
I haven’t found any GDD numbers for BWA. There are 2 generations in the northeast with crawlers present late spring/early summer and late summer/early fall. For the most part, the only stage that can be controlled is the crawler stage although horticultural oils and insecticidal soaps might penetrate the wax of the adults and can be used for the overwintering stage (be careful of foliage damage).
Scouting for crawlers can be done with a beat sheet (whacking branches over a white surface to find the amber colored crawlers) or with double sided tape around the trunk or branches to catch the crawlers.
I have heard growers say they have success with Asana XL (esfenvalerate) and OnyxPro is also labeled. Pesticides won’t reverse the damage but will limit insect populations. Spray trees around where you have removed trees or seen damage, especially downwind, as you likely won’t find the first insects on a tree.
I did find information that suggests Concolor fir and European silver fir are moderately resistant and Veitch and Momi fir are resistant. Turkish fir seems to have some resistance or tolerance, too. Douglas fir isn’t a host.
We are planning another Agritourism During COVID presentation so keep an eye out for the advertisement.
Have a great week!