#Tomato late blight cause cure free#

Buy certified seed potatoes to reduce the risk of introducing late blight.Early blight, caused by fungus Alternaria species usually appears when the plants are nearing the end of season or on plants with nutrient stress but it is usually not as devastating as late blight. Sometimes the spots may not be of late blight disease – if there are concentric rings of light and dark brown circles, often not crossing the veins, and spots do not have white sporulation on the underside of the leaves even under high humidity - the disease symptoms could be early blight. Also, check petunia, tomatillo and nightshade weed plants for infection.

Late blight infected tomato leaves and fruitĮarly blight: Concentric rings in spots and often not crossing the veins while the late blight (LB) spots are not restricted by veins.īoth tomato and potato plants growing in the field or garden should be checked for late blight symptoms – on leaves, stems and fruits. While severely infected tubers rot and can be easily graded out, the lightly infected tubers often survive storage and can initiate new infections in the next season.Ĭlose up of a leaf with water soaked rot on tomato petiole and sporulating white mildew on the underside of leaf. Infected potato tubers showing rusty-brown discoloration under the skin. Infection on potato stems showing sporulation in water soaked areas. These are rapidly growing spots in the crop canopy where humidity is high. After such storms, if the late blight inoculum is present, the new infections would usually develop in areas where the plants stay wet longer, in wind-protected areas, low lying spots or other topography that slows drying of plant leaves. The spores can travel many miles in wind-swept rainstorms. Late blight spores are microscopic and are spread both by splashing rain and wind. As the tissue dies, it turns grey to brown and dries up within a few days. Under conditions of high humidity, the fungus produces spores on the underside of leaves, which appears as a white mildew-like growth on the leaves and stems. In the early stages of infection the disease appears as water-soaked grey-green lesions on leaves and/or stems, often accompanied with light green discoloration around the darker area. Manitoba is part of a National Late Blight Working Group, which coordinates strain identification in various parts of Canada. tomatoes and potatoes may not show the same severity if infected with the same strain, while other strains may equally affect tomatoes and potatoes. Some of these new strains may not affect all host crops with the same aggressiveness, i.e. The fungus is changing and newer strains are appearing at a higher frequency. Late blight is caused by a moisture-loving fungus, Phytophthora infestans, which can infect potato and tomato, as well as other related plants like nightshade, petunia and tomatillo. To increase the chances of avoiding late blight infection in 2012, it is important to understand the disease and to be able to identify it early.

#Tomato late blight cause cure free#

For this reason, it is critical to start with potato seed or tomato transplants that are free of late blight. However, there can be no disease if the inoculum is absent. MAFRD is involved in the running of a Weather Network, which is used for late blight forecast. Strains active in other regions of North America, especially just south of the border, could affect what we see here in Manitoba.ĭevelopment of late blight is very much weather dependent. This suggests that the population of late blight strains in Manitoba is dynamic and variable. The late blight fungus strain was mostly US#24. However, the story in 2011 was very different - late blight disease in Manitoba was at moderate levels on potato, while the tomato crop escaped almost unaffected.

The pathogen strains were US#23 (mostly on tomato, some potato) and US#24 (mostly potato). Late blight devastated tomato plants in many home gardens throughout Manitoba. In 2010, there was an early onset of late blight in June and later that summer there was a major problem on tomatoes and potatoes across the Canadian prairies. Inspection of the greenhouse tomato transplants has to-date shown no infected plants in Manitoba in 2012. The distribution of late blight disease could depend on how effective the surveillance for late blight is and also the weather in general. These two facts could have an impact on the late blight development and progress in 2012. Florida supplies tomato seedlings to a large portion of the US. The strains of the fungus from Florida are reported to be changing and appear to be more tolerant to warmer temperatures. Late Blight Disease Management: Before It Becomes A Serious ProblemĪs early as February 2012, moderate to severe levels of late blight have been reported from Florida.