How to identify tomato late blight? These symptoms must be remembered
Late blight: All growth stages and leaves, stems, and fruits can be affected, with leaves and green fruits suffering the most severe damage. In seedlings, the disease generally starts with dark green water-soaked lesions on the leaves, then spreads to the stem, with dark brown rot near the petiole; as the disease progresses, the base of the young stem becomes water-soaked and constricted, and the plant wilts and collapses. In the adult plant stage, the disease starts from...
Late blight: All growth stages and leaves, stems, and fruits can be affected, with leaves and green fruits suffering the most severe damage. In seedlings, the disease generally starts with dark green water-soaked lesions on the leaves, then spreads to the stem, with dark brown rot near the petiole; as the disease progresses, the base of the young stem becomes water-soaked and constricted, and the plant wilts and collapses. In the adult plant stage, the disease starts from the lower leaves and develops upward, beginning at the leaf tips and leaf margins as dark green water-soaked lesions that gradually turn brown; in severe cases, the leaves of the entire plant dry up. Stem lesions are brown or dark brown, water-soaked, and slightly sunken. Fruit lesions are initially oily dark green, gradually turning dark brown to reddish brown, with a cloud-patterned appearance, rough and hardened. When humid, white mold can appear on all affected parts.
Notes: 1. Sometimes leaf lesions form a V shape from the leaf tip, or when conditions are unsuitable the diseased parts dry up and no mold layer is visible; when only leaves are affected, it is easily confused with gray mold. 2. When environmental conditions are especially suitable, the disease develops rapidly, with no obvious lesions on the leaves, but obvious white mold appears. 3. When only leaves are affected, it is easily confused with frost damage, but frost damage occurs on the upper leaves. 4. Improper fertilization can also cause leaf drying similar to late blight, also starting from the lower leaves, but it is evenly distributed across the whole field.