CIRCULAR 7 4 7, U. S. DEPARTMENT OF AGRICULTURE 



Figure 3. — Stripe smut on Kentucky bluegrass. 



Stripe Smut 



Stripe smut, a fungus 

 disease caused by Ustilago 

 striaeformis (West.) Niessl, 

 attacks many grasses and 

 is common on bluegrass. 

 Initial symptoms appear 

 as chlorotic stripes on the 

 blades. Later the stripes 

 become grayish-black (fig. 

 3) . Masses of smut spores 

 are released when the 

 stripes mature and rup- 

 ture. Spores are brown, 

 spherical to oval, and are 

 covered with short spines. 

 Severely infected plants 

 are stunted and dwarfed. 

 Stripe smut develops sys- 

 temically within its host. 

 Thus it is not seasonal in 

 its development and can 

 be found to a greater or 

 less degree any time during 

 the growing season. 



A second stripe smut, 

 caused by Urocystis agro- 

 pyri (Preuss) Schroet., at- 

 tacks several grasses, in- 

 cluding bluegrass, and can 

 be distinguished from the 

 first only by microscopic 

 examination of its spores, 

 which are formed in balls 

 with one to three fertile 

 spores surrounded by a 

 single layer of empty cells. 

 This smut is not so com- 

 mon on bluegrass as Usti- 

 lago striaeformis. 



