Once
uredinia appear on the surface of wheat leaves, a large number of urediospores may be liberated after rupture of the
uredinia and then be spread by air, which may result in secondary infections.
Uredinia abaxial, brown, rounded, scattered, 0.8-2 x 0.6-1 diameter.
The symptoms initially appear as small yellow pustules containing
uredinia, which may cover large portions of the abaxial leaf surface.
Uredinia hypophyllous, yellowish, minute, covered with ruptured epidermis, pulverulent, scattered over the whole leaf surface, surrounded by numerous incurved paraphyses.
Beginning in July 2010, and annually since, symptoms of brown to black foliar spotting with margins of chlorosis and signs of abundant
uredinia production were observed on plots of 3 year-old 'Alamo' and 9 year-old 'EG1101' switchgrass, established at the Leveck Animal Research Facility in Starkville, Mississippi (Figures.
Uredinia are observed initially in the dark dots that progressively acquire a light brown to red brown color and open in a minute pore releasing the colorless urediniospores, which become tan and accumulate around the pores (Balardin, 2002; Yorinori et al., 2004; Almeida et al., 2005).
The rating scale of infection responses in these evaluations consisted of four classes: R (resistant), MR (moderately resistant), MS (moderately susceptible), and S (susceptible) determined primarily on the basis of the size of
uredinia. Based on natural field infection in Colorado, Hatcher is moderately resistant to stripe rust (caused by Puccinia striiformis Westend.; 4.3 score, 1 = resistant and 9 = susceptible, n = 4 evaluations).
Two different components of reproductive output corresponding to different stages of the pathogen's life cycle, formation of
uredinia (pustules) on leaves and production of urediniospores by the
uredinia, are modeled as functions of the strains' inoculum and uredinial densities, respectively.
Uredinia amphigenous, subepidermal, golden brown to blackish brown, present in rows, scattered but somewhat compact, naked, 0.06-0.11 x 0.094-2 mm.