230 FUNGOID PESTS OF CULTIVATED PLANTS. 



The grains appear to be rather plumper and darker coloured than 

 usual. The spores with which they are filled are globose (14-20^u mostly 

 17ft diam.), and the surface is reticulated by a network of raised veins 

 (each pit about 8// diam.) and of a dark brown colour, seemingly black. 

 When the spores germinate, as they do readily, they produce secondary 

 spores or sporidiola which are long and thread-like. These sporidiola 

 copulate, or become united by a transverse process, something like a 

 capital H, and as a result a smaller or shorter tertiary spore or secondary 

 sporidiolum is produced. 



Much less common in this country than formerly. The seed grain 

 may be sprinkled with a solution of one pound of corrosive sublimate to 

 fifty gallons of water, taking care that the grain is wetted all over. 



This bunt is recorded for France, Belgium, Switzerland, Austria, 

 Germany, Finland, Italy, and North America. 



Sacc. Syll. vii. 1760 ; Cooke, Hdbk. No. 1519 ; Cooke, M. F. figs. 84- 

 91 ; Mass. PL Dis. p. 218, fig. 52 ; Mass. B. F. figs. 53-56 ; Plowr. Brit. 

 Ured. p. 283 ; Smith, Field Crops, p. 246, figs. 114-116. 



Another species (Tilletia lavis) with quite smooth spores is most 

 common in the United States. 



SUMMER WHEAT MILDEW. 

 Puccinia graminis (Pers.), PI. XXII. fig. 3. 



This very common mildew on the leaves and culms of Wheat and 

 grasses retains its old name, but it has gained the reputation of having 

 its first stage, or cluster-cups, on the leaves of Berberis and Mahonia. 



The uredospores are produced in elliptical or linear pustules, of a rusty- 

 brown colour, and in older times were known as Uredo linearis. They are 

 for the most part ellipsoid, sometimes clavate (24-45 x 14-21/z), rough 

 externally, of a tawny-yellow colour, at first with a short colourless pedicel. 

 This is commonly known as the " Wheat rust." 



The teleutospores are later, and are produced in elongated or linear, 

 nearly black pustules, which are crust-like, through the teleutospores 

 adhering together, and not becoming powdery like the rust, The spores 

 are club-shaped, or somewhat fusoid, with the apex rounded, or teat-like 

 and obtuse, attenuated downwards, and divided by a cross partition into 

 two rather unequal cells, the lower one narrowed into a persistent and 

 rather long pedicle ; surface smooth, pale tawny-yellow (34-60 x 12-22//), 

 spore coat rather thickened at the apex, and mostly darker. 



Known in France, Belgium, Germany, Sweden, Finland, Switzerland, 

 Austria, Italy, Asiatic Siberia, North America, La Plata, Australia, New 

 Zealand. 



Early sown and early ripening varieties escape rust best. 



Sacc. Syll. vii. 2191 ; Smith, Field Crops, p. 147, figs. 72-81 ; Mass. 

 PL Dis. p. 247, fig. 63 ; Ward, Ann. Bot. ii. (1888), No. 6 ; Grevillea, x. 

 p. 33 ; Gard. Chron. Feb. 17, 1866, March 6, 1886 ; Cooke, M. F. p. 202, 

 figs. 57-59 ; Cooke, Hdbk, No. 1462 ; Plowr. Brit. Ured. p. 162. 



