282 Transactions British Mycological Society. 



Smithfield Show. On enquiry it was found that the Kale 

 had been grown in Norfolk. 



Dec. i^th. After several hard frosts it was noted that the 

 " subinfections " were still present on Marrow-stemmed Kale but 

 only, very few conidia could be seen. The infections on Brussels 

 Sprouts were quite vigorous with a number of young conidio- 

 phores and conidia. On Rape fresh looking powdery patches of 

 mildew were numerous. On Swede it was now difficult to find 

 any mildew except on the lower surface of the leaves. 



Dec. lyfh. A number of fresh spots of mildew were found on 

 the under surface of Swede leaves, all of them were quite powdery 

 with conidia. "Subinfections" were very numerous on Thou- 

 sand Head Kale. 



Jan. 6th. During the previous fortnight the' temperature 

 dropped at times to 17° F. and there had been several inches of 

 snow. " Subinfections " on Thousand Head Kale were found to 

 be in a quite healthy condition. Small patches of mycelium were 

 found on Swedes but without conidia. 



Jan. i^th. Thousand Head Kale leaves, covered with snow^, 

 were collected, and under the snow were found seemingly 

 healthy patches of mycelium. These leaves were brought into 

 a warm laboratory and in a few days developed a large number 

 of conidia on the patches of mycelium. 



Jait. 26th. Temperature during previous week at times 

 dropped to 12° F. 



March yth. Thousand Head Kale observed with small " sub- 

 infections " still alive and a few conidia. 



Early May. " Subinfections " on Thousand Head Kale and 

 Marrow-stemmed Kale in the same dormant condition. 



Mid-May. "Subinfections " on a Thousand Head Kale plant 

 commenced to spread first on to the lower leaves and then on 

 to the new upper leaves. Infections then appeared on a Rape 

 plant and a Swede plant standing next to the Kale. 



It would appear therefore from the above observations that 

 an actual infection of the plant does occur in the case of "sub- 

 infections" and that it is quite possible in Nature for a "sub- 

 infection " to continue existence as such and later grow out into 

 a full infection. 



As these "subinfections" have been found to occur quite 

 naturally in the field, it shows 'that they are not merely a 

 phenomenon caused by carrying out inoculations under cultural 

 conditions, nor do they depend on a large number of conidia 

 being sown on one spot as suggested by Salmon (7), though that 

 may be the cause in certain cases, noted with artificial inocula- 

 tions. 



It would seem possible that "subinfections" are the pre- 



