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Pyrenophora tritici-repentis and Drechslera tritici-repentis is a necrotrophic plant pathogen of fungal origin, phylum Ascomycota. [1] The pathogen causes a disease originally named yellow spot but now commonly called tan spot, yellow leaf spot, yellow leaf blotch or helminthosporiosis.
Symptoms can overlap across causal agents, however differing signs and symptoms of certain pathogens can lead to the diagnosis of the type of leaf spot disease. Prolonged wet and humid conditions promote leaf spot disease and most pathogens are spread by wind, splashing rain or irrigation that carry the disease to other leaves. [2]
The lesions found in Northern corn leaf blight are more acute if the leaves above the ear are infected during or soon after flowering of the plant. [4] In susceptible corn hybrids, lesions are also found on the husk of ears or leaf sheaths. In partially resistant hybrids, these lesions tend to be smaller due to reduced spore formation.
The most proficient and economical method to reduce yield losses from corn grey leaf spot is by introducing resistant plant varieties. [17] [18] In places where leaf spot occurs, these crops can ultimately grow and still be resistant to the disease. Although the disease is not eliminated and resistant varieties show disease symptoms, at the end ...
A raspberry leaf spot infection initially causes dark green circular spots on the upper side of young leaves, which will eventually turn tan or gray. [3] These spots are typically 1–2 millimetres (0.039–0.079 in) in diameter, but can get as big as 4–6 millimetres (0.16–0.24 in). [4]
An albino corn plant with no chlorophyll (left) beside a normal plant (right) In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll.As chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white.
At initial stages, small yellow spots are formed on the surface of the leaf. These spots may be better observed using assistance of a light source. As the disease progresses, lesions start to form on the leaves, stems, pod, and petioles. Lesions are initially small, turning from gray to tan or brown as they increase in size and the disease gets ...
Septoria lycopersici infects the tomato leaves via the stomata and also by direct penetration of epidermal cells. [3] Symptoms generally include circular or angular lesions most commonly found on the older, lower leaves of the plant. [1] The lesions are generally 2–5 mm in diameter and have a greyish center with brown margins.