230 AGRICULTURAL EXPERIMENT STATION. [Jan. 



proportion to the amount of rust present on the well-fed 

 plants. 



The Club Boot of Cabbages (^Plasmodiophora Brassicce 

 Wor.) appeared for the first time on a part of the station 

 grounds during the past season. The first specimens were 

 obtained when the largest leaves were about six inches long. 

 At this time, in the worst specimens the main root and its 

 lateral branches were attacked and swollen into a nearly 

 solid mass of the size of a hen's egg. The parts of the 

 affected plants above ground did not at this time difier 

 essentially in appearance from their neighbors, and were 

 recognizable chiefly by the fact that in warm, sunny weather 

 the foliage became wilted from the lack of sufficient root 

 hairs on their swollen roots to absorb the necessary water 

 to supply the demands of active transpiration. These 

 plants failed entirely to form " heads," and were therefore 

 rendered worthless by the disease. Microscopic examina- 

 tion of the diseased roots at different times showed the 

 various stages in the development ot the parasite as they 

 have been described and figured by Woronin. 



Early in the season, just after the spring ploughing, soil 

 was taken from a field which had been planted to cabbages 

 the previous season and had produced a considerable number 

 of " stump-footed " ones. This soil was placed in a flower- 

 pot in the greenhouse and sown with cabbage seed. In due 

 time some of the seedlings were attacked by the club root 

 fungus in characteristic fashion, this showing the survival in 

 the soil and their probable pretty general distribution 

 through it, after ploughing, since a single flower-pot full 

 taken at random contained at least several of them. 



It is a matter of o-eneral observation amons; market srar- 

 deners and others that on some soils, especially heavy and 

 moist ones, it is not profitable to plant cabbages two years 

 in succession, on account of the prevalence of club root the 

 second year. But it has also been remarked that two crops 

 equally free from disease may be raised in one season. This 

 fact is interesting as a practical demonstration of the fact 

 that the spores of the club-root fungus are resting .spores^ 

 and require a season of quiescence before they are able to 

 germinate and reproduce the disease. 



