74 AGRICULTURAL RESEARCH AND THE FARMER : 



Rust Diseases of Oats. — During the past two years research 

 has been carried out on two rust diseases of oats — Crown Rust 

 and Black Stem Rust. The former was at least partially 

 responsible for a much reduced yield in the oat crop of North 

 Wales in 1920, and the latter attacks the oats every year 

 in one locahty in Anglesey, sometimes causing a practically 

 complete loss of the crop. The research has so far been produc- 

 tive of results in three directions. In the first place, varieties 

 of oats resistant to these two diseases have been discovered. 

 The method of early spring infection of Crown Rust has been 

 shown to be due in all probability to overwintering of the summer 

 stage of the disease, whereas the evidence so far obtained is 

 against the likelihood of overwintering in the case of Black 

 Stem Rust. Finally, the research has shown that many grasses 

 are affected by these two rust fungi, and that infected grasses 

 may induce the diseases in oats and vice versa. 



Agricultural and Horticultural Research Station, 

 Long Ashton, Bristol. 

 Sulphur as a Fungicide. — The value of sulphur and related 

 substances such as lime-sulphur and liver of sulphur for the 

 control of many fungoid diseases is well recognised, but the 

 manner of their action is not understood. It is of peculiar 

 interest , because it is effective not only at the places where the 

 material is in immediate contact but at some distance away 

 also. It is this latter feature which offers important possibilities 

 of practical utiHsation provided that it can be suitably controlled. 

 These points have been under investigation for the past three 

 years and much new and significant information has been gained. 

 The action at a distance has been very definitely estabhshed and 

 its mechanism is now explained. It has been proved that the 

 poisonous action of sulphur is very selective towards different 

 fungi, some, including mildews, generally being very sensitive 

 and easily killed; others, e.g., the apple and pear scab fungi 

 only moderately affected; others again, e.g., the apple canker 

 fungus, grow freely in its presence. Minute amounts of sulphur 

 in the atmosphere are sufficient to render growth of the more 

 sensitive forms impossible. The further progress of the work 

 depends in m.any ways upon the possibility of detection and 

 estimation of these traces, a chemical problem of considerable 

 difficulty on which attention is being concentrated. 



Canker of Apple Trees. — This is one of the most serious pests 

 of the fruit-grower, especially in the West of England. Until 

 recently it has been regarded as exclusively a " wound " parasite.. 



