Disease Cycle
The disease cycle of Ustilago nigra is similar to that of U. hordei, the cause of covered smut of barley. The teliospores survive on the surface or in the soil. In some cases, the teliospores that are deposited under the hull, may germinate immediately. The mycelium then grows into the lower layers of the seed and then remains dormant until seed germination.
Infection of seedling occurs between germination and emergence. Infection can occur from seed-borne teliospores or by teliospores residing in the soil. Relatively dry soil at temperatures of 15-21 C, are most favorable for infection. The invading mycelium becomes established within the growing point. As the plant enters the boot stage, the mycelium grows rapidly into the foral tissue which is converted to masses of black teliospores. Teliospores are disseminated by wind or during combining. The teliospores may remain viable for several spores.
Read more about this topic: False Loose Smut
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