Tim Elkner, Penn State Extension in Lancaster Co. is reporting the following Allium Leafminer activity:
During my farm visits yesterday (4/6/17) to set traps I found evidence of activity of adult allium leaf miner (ALM) on 2 of 3 sites here in Lancaster County.
At one site there was feeding damage on both onion transplants being produced in one greenhouse as well as feeding damage on scallions planted in the ground in a second structure.
At the second farm there was feeding damage to shallot seedlings being transplanted as well as on wild alliums in the nearby fencerow.
On the second location I would say that the feeding was very recent – 1-2 days at most since fecal matter was present on the leaves and we did have rain on Tuesday (4/4/17).
There was no evidence of larval feeding at either site.
I am posting information today (4/7/17) at the Leola and Weaverland produce auctions here in Lancaster and Dr. Shelby Fleischer did update the 1-800-PENN-IPM line yesterday.
For those who may not be aware – we have a line on the 1-800-PENN-IPM line this season dedicated to ALM and will be updating it regularly regarding activity of ALM in both the spring and fall.
For those in affected counties (See attached map) this pest is either active (we do not know about regional appearance yet – it would be useful to know if/when they become active in your area) or will be soon.
Last season I had numerous growers who were unaware of this pest and lost all or most of several spring allium crops so ALM can be a significant problem.
A possible phenological indicator may be flowering in peach and cherry – both of which are at or near full bloom here in Lancaster.
Further information on this relatively new pest is available here.