I know most of you are not residents of western Washington, but this information might be of interest to gardeners everywhere.
Pest: Late blight (Phytophthora infestans)
Hosts at risk: Tomato and potato
Conditions of risk: cool, moist environment
Found: Images typical of late blight infection on tomato have been submitted from two Puget Sound area (King/Snohomish county) farms. Growing conditions were plants in field soil where the area was covered with a plastic hoop structure.
Potential impact: Significant crop losses may occur if not managed properly.
What action should be taken: Scout for evidence of the pathogen on the foliage, stems of tomato or potato, as well as the fruits of tomato. Look for black discoloration to the foliage and a halo of sporulation around the edge of the damage if conditions are moist. Keep the foliage as dry as possible. Maintain good air circulation around plants. A variety of preventative fungicides (both organic and conventional options) is available – click on the links above for tomato and potato.
Information is also available on the PNW Plant Disease Management Handbook website.
Ooh, late blight. Late blight swept through veg. gardens here in MA a couple of years ago, and ruined whole tomato crops. In a wet summer season, it only takes a few short weeks, almost, to devastate a planting. Fortunately, the blight doesn’t survive our chilly winters (though I wonder about last winter, which was extremely warm), so the problem won’t necessarily recur in a second year. But while the fungus is active (we learned that it likely started here from tomatoes bought at big box stores), it can and will decimate a crop, and using the few good parts of any tomato for relishes, salsas, etc. — is usually the only way to salvage any part of the year’s production.
Well, I guess one benefit of the hot and extremely dry summer we are having is a low probability of late blight. Actually, looks like a good year for tomatoes as long as I remember to water.