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Aster yellows is a chronic, systemic plant disease caused by several bacteria called phytoplasma. [1] The aster yellows phytoplasma (AYP) affects 300 species in 38 families of broad-leaf herbaceous plants, primarily in the aster family, as well as important cereal crops such as wheat and barley.
[10] In certain corn varieties, kernels can be infected later in the growing season after flowering occurs. Although corn kernels can be a source of inoculuum, seed transmission is quite rare. [9] Commercial seed lots obtain phytosanitary certification for Stewart's Wilt by field inspection. The presence of the bacteria in the field at any ...
Lower leaves (older leaves) show symptoms first, since the plant will move nitrogen from older tissues to more important younger ones. [7] Nevertheless, plants are reported to show nitrogen deficiency symptoms at different parts. For example, Nitrogen deficiency of tea is identified by retarded shoot growth and yellowing of younger leaves. [8]
Corn grey leaf spot can be an extremely devastating disease as potential yield losses range from 5 to 40 US bushels per acre (440 to 3,480 L/ha). At higher disease levels, even greater losses can result. When a corn plant's ability to store and produce carbohydrates (glucose) in the grain is diminished, yield losses take place.
As the disease progresses, the lesions grow together and create large areas of dead leaf tissue. 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.
Southern corn leaf blight (SCLB) is a fungal disease of maize caused by the plant pathogen Bipolaris maydis (also known as Cochliobolus heterostrophus in its teleomorph state). The fungus is an Ascomycete and can use conidia or ascospores to infect. [ 1 ]
[10] [11] The spores enter the corn through the silks and thus infect the kernel. Conidiophores and conidia are produced in the spring from sclerotial surfaces. There is a secondary inoculum for A. flavus, which is conidia on leaf parts and leaves. A. flavus grows on leaves after damage by leaf-feeding insects. Insects are said to be a source ...
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.