Tomato Late Blight
 Late blight has not been common in New England but when it occurs it can be very destructive. Protectant fungicides are a key tool for management; howver, many strains of Late Blight have become resistant to mefenoxam. When resistant strains are present, early blight fungicides will give as much protection against late blight as mefenoxam combinations. Several forecasting systems can be used for identifying Late Blight infection periods. Avoid the use of overhead irrigation. Promptly plow under old tomato fields after harvest. Eliminate cull piles and volunteer plants of both tomato and potato. Some resistant cultivars are available.
azoxystrobin (Quadris): 6.2 fl oz/A (0 dh, REI 4h, Group 11). Apply at the first sign of disease and rotate with chlorothalonil after 7 to 14 days if necessary. Do not rotate with other strobilurins such as Cabrio. See label for precautions.
cyazofamid (Ranman): 2.1-2.75 fl oz/A. (0 dh, REI 12h, Group 21). Alternate sprays of Ranman with a fungicide with a different mode of action.
cymoxanil (Curzate 60 DF): 3.2 oz/A. (3 dh, REI 12h, Group 27). Use only in combination of a laeled rate of a protectant fungicide (copper, chlorothalonil). Apply as a protectant on a 5-7 day schedule.
chlorothalonil (Bravo Ultrex WDG): 1.3 to 1.8 lb/A (0 dh, REI 12h, Group M5). Apply at the first sign of disease and repeat after 7 to 14 days if necessary.
dimethomorph (Forum): 6 oz/A. (0 dh, REI 12 h, Group 15). Must be applied as a tank mix with another fungicide with a different mode of action. Do not make more than two consecutive applications of Forum before alternating to a non-Group 15 fungicide.
famoxadone plus cymoxanil (Tanos): 8 oz/A. (3 dh, REI 12h, Groups 11 and 27). Must be tank mixed with an appropriate contact fungicide with a different mode of action and alternated with a fungicide from a different group (FRAC Code) after one application. Do not alternate with Quadris, Cabrio, or Flint.
fenamidone (Reason 500 SC): 5.5-8.2 lb/A. (14 dh, REI 12h, Group 11). Begin applications as soon as crop or environmental conditions favor disease development. Do not make more than one application before rotating to a fungicide from a different resistance management group (non-Group 11).
mancozeb plus zoxamide (Gavel 75DF): 1.5 to 2.0 lb/A (5dh, REI 48h, Groups M3 & 22). Apply preventively.
mefenoxam plus manzate (Ridomil Gold MZ): 2.5 lb./A (5 dh, REI 48h, Groups 4 & M3). Apply at the first sign of late blight; repeat at 14-day intervals. Do not use more than 3 applications per crop. Do not plant any crop which is not registered for use with Ridomil Gold active ingredient in treated soil for a period of 12 months.
mefenoxam plus chlorothalonil (Ridomil Bravo): 2 lb/A (0 dh, REI 48h, Groups 4 & M5). Apply at the first sign of late blight and continue every 14 days.
potassium salts of phosphoric acid (Phostrol, Fosphite, ProPhyt): Rates vary with formulation. See label. Do not apply to heat or moisture stressed plants or to plants recently treated with copper.
pyraclostrobin (Cabrio EG): 8 to 12 oz/A (0 dh, REI 12h, Group 11). Apply at the first sign of disease and reapply after 7 to 14 days if necessary. Apply only six applications per season or 96 oz/A. Do not rotate with other strobilurins such as Quadris.
For Current information on production methods (including varieties, spacing, seeding, and fertility), weed, disease, and insect management, please visit the New England Vegetable Management Guide website.
Below you will find additional information on managing this crop, including photos of insects and diseases in this crop, fact sheets, articles, and power point presentations, when available.
|
