In the process of plant growth, when plants are infected by other organisms or encounter inappropriate growth environment conditions, a series of abnormal pathological changes and various pathologies will occur in the physiology, organization and morphology of plants. It leads to abnormal growth and development, and finally shows a decline in yield and quality, and even leads to plant death. This phenomenon is called plant disease.
The pathological characteristics of plants in physiology, tissue structure and morphology caused by pathogens or adverse environmental conditions are called plant disease symptoms. Generally speaking, the pathological changes that can be directly observed by the naked eye are called macroscopic symptoms. Lesions that can only be distinguished by a microscope are called microscopic symptoms.
Disease analysis
Microscopic symptoms are mostly used in the study of diseased cells or tissues, and only have certain reference value in the diagnosis of plant virus diseases. Such as observing whether there are necrotic cells in phloem, whether there are proliferative structures in sieve tubes and ducts, and the shapes and types of various inclusions in diseased cells infected with viral diseases.
Rust is the most common disease. Oval irregular brown spots will appear on the leaves of plants infected with rust, and the color of leaves will gradually become lighter. In plants infected with brown spot, brown circular spots of different sizes will appear on the leaves at first, and black mold will grow on the later spots, which will cause the plants to wither if not treated in time. The leaves of plants infected with powdery mildew will turn light gray, the leaves will begin to curl, and the surface of the leaves will be covered with a layer of white powder. Plants with serious diseases will wither, lose their leaves and not bloom.