Folks--This just in from Vern Grubinger: I just got word that the UVM plant diagnostic clinic confirmed late blight on tomatoes from a home garden in Jericho, VT. Be sure to scout your fields regularly so you can catch the disease early if it arrives. For many excellent images of the disease to help with identification go to: http://www.longislandhort.cornell.edu/vegpath/photos/lateblight_tomato.htm#images
For assistance with positive identification send samples of suspected plants to: UVM Plant Diagnostic Clinic 201 Jeffords Building 63 Carrigan Drive University of Vermont Burlington, VT 05405
Fungicides allowed for use on organic farms that show some efficacy against late blight and are registered in VT are: Nu-Cop 50 WP and Champ WG. These both contain 77% copper hydroxide and must be applied prior to infection to the entire crop canopy on a regular spray schedule in order to be effective. Champ WG is available from Crop Production Services in Addison VT: 802-759-2022 and NuCop 50WP is available from Helena Chemical in western MA: 413-247-3126.
Dr. Tom Zitter at Cornell has compiled tables of conventional fungicides for use against late blight, in order of preference, from best to poorest performance, for potato:
and for tomato: