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Germination can also refer to the emergence of cells from resting spores and the growth of sporeling hyphae or thalli from spores in fungi, algae and some plants. Conidia are asexual reproductive (reproduction without the fusing of gametes) spores of fungi which germinate under specific conditions. A variety of cells can be formed from the ...
Rhizoctonia solani root rot on corn roots, magnified 0.63X. Damping off can be prevented or controlled in several different ways. Sowing seeds in a sterilized growing medium can be effective, although fungal spores may still be introduced to the medium, either on the seeds themselves or after sowing (in water or on the wind).
The life-cycle of dry rot can be broken down into four main stages. Dry rot begins as a microscopic spore which, in high enough concentrations, can resemble a fine orange dust. If the spores are subjected to sufficient moisture, they will germinate and begin to grow fine white strands known as hyphae.
Dry rot is spread by spores which are present in most buildings. The minimum moisture content of timber for spore germination is 28–30% (lower than other rots), and the relative humidity must be in excess of 95%. Spores are resistant to desiccation and may still be viable for germination when they are several years old. [2]
True dormancy or inherent (or innate) dormancy is caused by conditions within the seed that prevent germination even if the conditions are favorable. [7] Imposed dormancy is caused by the external conditions that remain unsuitable for germination [8] Seed dormancy can be divided into two major categories based on what part of the seed produces dormancy: exogenous and endogenous. [9]
The primary inocula are the ascospores, sexual spores which are produced in the perithecia. [4] Spores are forcibly discharged and can germinate within six hours upon landing on the plant surface. The scab disease is monocyclic; after one cycle of infection with ascospores, the fungus produces macroconidia by asexual reproduction. [5]
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The spores are carried by the wind, and they become the source of inoculum in subsequent generations. [5] As the pathogen continues to develop in the host plant, there may also be production of conidia on the leaf surface. It is the conidia and the conidiophores that cause the white, downy growth on the undersides of the leaves.