![]() ![]() ![]() We've found that history will repeat itself,' says Tammy Sons ![]() 'Tomato blight spores can stay in the ground for for 3 to 4 years. Never plant tomatoes in soil or compost that has previously contained diseased plants. Plant tomatoes in a disease free location.Try to water the soil only and keep the leaves and plants dry. This is to avoid the plants sitting damp all night. This avoids leaves resting on damp soil, and also helps air circulation and speeds the ripening of tomatoes by providing them with maximum sun exposure. Remove lower leaves as the fruits develop.'Bush varieties grown in pots can be trimmed and partially supported with a bamboo cane to avoid a dense mass of foliage,' says Simon Crawford. Support bush tomato plants with a stake to keep their leaves off the soil, or tie up cordon tomatoes regularly with soft twine to improve air circulation. Likewise, pick a well ventilated spot for growing the tomatoes outside. If growing tomato plants in a greenhouse or polytunnel, avoid these becoming too humid by keeping them well ventilated. So learn how to prune tomato plants properly. 'Environmental control must focus on reducing the likelihood of leaves remaining wet for an extended period, so trimming foliage and side-shoots to maximise air movement and ensure the evaporation of surface moisture is essential,' explains Simon Crawford. The following environmental controls can help to prevent the occurrence or spread of tomato blight: Overhead irrigation can promote foliar fungal disease due to longer periods of leaf wetness.(Image credit: Getty Images) Environmental controls for tomato blight.Cultivars vary in tolerance to early blight.Ensure transplants are healthy and free of disease.Reduce early blight inoculum by following a 3 to 4 year crop rotation.Application should continue until close to harvest. Extend the schedule to 12- 14 days in warm, dry weather if diseases are under control. Repeat at 5- 7 day intervals during continuous moist weather. If this is unavailable, begin a preventative spray program when the first fruits are about walnut size. Unless the fungus is present on transplants, lesions generally don’t show up until flowering. Temperatures of 17- 24☌ (63- 75☏) and extended leaf wetness favour early blight development. Spores are present throughout the growing season and may be carried long distances in the wind. It is spread by wind and splashing water. The fungus that causes early blight survive on decayed plant material in soil and can be seed borne. Lesions may also appear on stems and blossoms (a cause of blossom drop).įruit infection is uncommon, showing up as a blackened area, similar in appearance to blossom-end rot, but at the stem end of the fruit or as blotches or sunken areas (see Black Mold). Lesions may coalesce to form large dead areas on the leaf. They are often bordered by leaf veins.Įarly blight may cause browning of leaf edges. As lesions enlarge, their shape may become irregular. ![]() If the disease is severe, lesions also appear on younger leaves. Lesions become quite large and are often associated with considerable leaf yellowing. The tissue surrounding the spot may be yellow. Spots are circular to angular with dark concentric rings (target spot). Lesions first appear on leaves as dark brown to black spots, 8- 13 mm (5/16- 1/2 in.) in size, on older foliage, but can grow much larger. The first signs of disease often appear deep in the canopy where the leaves stay wet. Applications should continue until close to harvest. Temperatures of 17- 24☌ (63- 75☏) and extended leaf wetness favour early blight development.Įarly blight lesions can be distinguished from other lesions on the foliage by the presence of concentric rings. Spores are present throughout the growing season and may be carried long distances in the wind or spread by splashing water. Septoria Leaf Spot (Early blight lesions grow much larger than Septoria lesions.)Įarly blight overwinters in infected crop residue and can be carried by infected seed and weed hosts.
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