rucciNiA. 345 



the uredospores, developed from long sporophores, and are in 

 this way distinguished from those of Piicc. ruhigo-vera, which 

 are very short. The teleutospores germinate in spring after 

 hibernation, each cell giving off a single germ-tube. 



Both uredospores and teleutospores are injurious to our 

 cereals, — wheat, oats, and rye. They may also be found on 

 the following species of grasses : Anthoocanthum, Alopecurus 

 Phleum, Agrostis, Aim, Avena, Briza, ArrJienatherum, Poa, 

 Dcictglis, Festuca, Bromus, Triticum, Secale, Elymus, Hordeum, 

 Lolium, Agropyrum, Andropogon, Bryzopyrwm, etc. 



The disease may ruin a whole harvest of grain, and render 

 the straw disagreeable, if not dangerous, for stable use (see 

 also p. 84). Kemoval of barberry bushes is said to reduce the 

 rust, although many believe that the barberry is not necessary 

 for the existence of the fungus.^ Plowright, for example, found 

 that sporidia from teleutospores infected wheat-seedlings directly, 

 without intervention of the aecidiospore stage. It is also possible 

 that the mycelium hibernates like that of Puce, rubigd-vera, in 

 some wild grass, to grow again and produce uredospores in spring. 



No very effective measures against this fungus are known. 

 Early sowing has been suggested; and certain varieties of grain, 

 known to be less liable to attack than others, might be used. 



Eriksson and Henning,^ from the results of their infection- 

 experiments, have provisionally distinguished the following 

 varieties of P. graminis : 



A. Definite — (a) distinct varieties : 



1. Var. secalis on Secale cereale, Hordeum vulgare, Triticum 



repens, and Elymu,& arenarius. 



2. Var. avcnae on Avena sativa, Milium effusum, Alopecurus 



pratensis, Dactylis glomerata (and Avena elatior). 



3. Var. airae on Aira caespitosa. 



((8) somewhat uncertain varieties : 



4. Var. agrostis on Agrostis canina, and A. stolonifera. 



5. Var. poae on Poa compressa (and P. pratensis). 



B. Not sharply defined : 



6. Var. triiici on Triticum vulgare. 



^ An interesting discussion of this subjeot is given by Wor. G. Smith (Diseases 

 of Crops, Chap. xxv.). (Edit.) 



-Eriksson and Henning, " Untersuchungen lib. A. Getreideroste,'' Zeitsch. 

 J. Pjlanzenhrankheiteii, 1894. 



