Again, affected soil can splash onto plant leaves or get carried by birds or other critters. Additionally, any spores in the soil can splash up onto plant leaves when you water from above. Dry leaves are not great environments for fungal spores. Here are five things you can do to help stop blight before it starts. The best way to stop vegetable blight from ruining your tomatoes is to prevent it. If your tomatoes (or potatoes) are carrying late blight, the only thing you can do is destroy them, as well as a perimeter of healthy plants around them. Firm, brown spots develop on tomato fruit.” Brown to blackish lesions also develop on upper stems. Sometimes the lesion border is yellow or has a water-soaked appearance.
The University of Massachusetts Extension Vegetable Program describes the tell-tale symptoms as “large (at least nickel-sized) olive-green to brown spots on leaves with slightly fuzzy white fungal growth on the underside when conditions have been humid (early morning or after rain). Late blight was the pathogen responsible for the Irish potato famine in the 1840s. Late blight ( Phytophthora infestans ) can spread rapidly and obliterate tomatoes and potatoes in a matter of days. The most severe type of vegetable blight is late blight. Leaf spot can spread rapidly and destroy foliage, but does not usually affect the fruit. This vegetable blight primarily infects foliage, starting with circular lesions on the lower leaves. The most frequent result of early blight is the loss of foliage.Īnother common problem is septoria leaf spot. Early blight starts as small brown or black lesions, often developing the appearance of a target or bull’s eye. Early blight won’t necessarily ruin your vegetables, but it will significantly limit production. Leaves may have become wet from condensation dripping from the tunnel roof, leaks in top of irrigation tubing or water depositing on leaves under high humidity.There are three different types of blight that may infect your tomatoes. Following images taken on 17 June 2019 by Sandy Menasha, Vegetable Specialist Cornell Cooperative Extension of Suffolk County, document that early blight can occur in high tunnel tomatoes. The causal fungus can also cause symptoms on stems and fruit.īelow: Symptoms of early blight on fruit calyx and stem.īelow: One reason tomatoes are grown in high tunnels is to avoid diseases like early blight that are caused by pathogens that need leaves to be wet for several hours in order to infect. Sources of the pathogen are infested seed, debris from infected plants left in or on the soil (where it can survive at least 1 year), and spores from other affected plants dispersed typically short distances by wind, water, insects, or animals.īelow: Early blight symptoms first appear on older leaves near the base of the plant.īelow: Tomato leaves infected with early blight.īelow: Note the ‘target’ appearance of concentric rings. Young seedlings can be killed by stem lesions developing at their base. The causal fungal pathogen also produces symptoms on stems and fruit. Spots first appear on older leaves near the base of the plant. The main symptom of early blight is round leaf spots with a characteristic target appearance due to the dark concentric rings that develop in most spots.