Physoderma alfalfae

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Physoderma alfalfae is a plant pathogen that affects alfalfa plants. It is a type of fungus that causes a disease known as Physoderma brown spot. The pathogen primarily infects alfalfa leaves, leading to the formation of characteristic brown spots on the foliage.

Symptoms

The symptoms of Physoderma alfalfae infection typically manifest as small, circular brown spots on the leaves of alfalfa plants. These spots may coalesce to form larger lesions, which can eventually cause leaf yellowing and necrosis. In severe cases, the disease can lead to defoliation and reduced plant vigor.

Disease Cycle

Physoderma alfalfae overwinters in infected plant debris in the soil. In the spring, the pathogen produces spores that are dispersed by wind or rain onto healthy alfalfa plants. Upon landing on a susceptible host, the spores germinate and penetrate the plant tissue, initiating infection. The fungus then colonizes the plant, leading to the development of characteristic symptoms.

Management

Management of Physoderma brown spot in alfalfa involves cultural practices such as crop rotation and sanitation to reduce the buildup of inoculum in the soil. Fungicides may also be used to control the disease, although their efficacy can vary. Planting resistant alfalfa varieties can help mitigate the impact of Physoderma alfalfae on crop yield.