Here’s a late blight update from Vern Grubinger.
The UVM Plant Diagnostic Clinic has confirmed late blight on tomato from a home garden in Lamoille County. The disease has also been confirmed in eastern NY and western MA. In NY the strain has been identified as the same one we had last year, US22, which is more aggressive on tomato than potato.
Organic growers wishing to protect their tomato/potato crops should apply an OMRI approved formulation of copper such as NuCop 50 WP or Champ WG at least weekly, following label instructions. Comprehensive recommendations for late blight management in organic tomato are at: http://vegetablemdonline.ppath.cornell.edu/NewsArticles/Tom_LB_OrganicMgt10.html
For conventional late blight management, this from Jude Boucher at UConn Extension: Some of the most effective products which have proved themselves against late blight in the past include: Revus, Revus Top, Ranman, Presidio (not registered for potatoes), Previcur Flex, Tanos and Curzate. If the weather moves from dry to wet, you should consider alternating between two of these products. Remember to include a protectant fungicide such as a Bravo or a copper type product for resistance management purposes and observe the days-to-harvest restriction listed on the label.
Excellent late blight information and photos can be found at: http://www.longislandhort.cornell.edu/vegpath/photos/lateblight_tomato.htm
If you suspect the disease on your crop please send a sample asap to:
UVM PLant Diagnostic Clinic
201 Jeffords Hall
63 Carrigan Drive
Burlington, VT 05405