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ROTTENNESS OF TURNIPS AND SWEDES. [Sept. 1896. 



Botrytis also appears to be identical with that of Frank, which, 

 however, has the peziza-stage. 



It is possible that this Botrytis is the conidial stage of 

 S. sclerotiorum ; but, again, this point cannot be definitely 

 ascertained until the peziza-stage is found. The supposition 

 would be correct if the sclerotia on the potato-haulms in this 

 country and those near Stavanger are identical. The Norwegian 

 fungus and the one described by Worthington Smith produced 

 the Peziza, and were determined as S. sclerotiorum. On this 

 assumption S. sclerotiorum under certain conditions, as in some 

 localities, produces a Peziza, but in other localities a Botrytis, 

 which differs only slightly from B. cinerea, so that the two have 

 not been separated from each other. This is at variance with 

 de Bary's statement that S. sclerotiorum does not produce a 

 Botrytis. 



Summary. 



The destruction of swedes and turnips in store is largely 

 -caused by a species of Botrytis, a common fungus having the 

 faculty of living both as a parasite and a saprophyte. 



This fungus is propagated by means of conidia, which readily 

 germinate on the moist surface of a wounded root, and can 

 infect it when living either in the field or stored in the pit, the 

 rottenness proceeding as the fungus extends. When pure 

 cultures of the conidia obtained from diseased roots in the pits 

 were sown upon perfectly sound sterile pieces of swede in test- 

 tubes, under carefully guarded conditions, the sound swede 

 became infected, and hyphge were developed which rapidly 

 extended until the whole substratum was rendered brown and 

 rotten. A similar experiment tried on turnips actually growing 

 in the ground produced precisely the same results, the infection 

 from the pure sowings of conidia spread throughout the roots, 

 leaving them thoroughly diseased, and in appearance exactly 

 resembling those found attacked in the pits, and the fungus 

 pervading the rotten mass was found to be the same Botrytis. 



The Botrytis is also found living upon decaying potato- 

 haulms., upon swede and turnip tops, and on decaying vegetable 

 anatter generally. The conidia from the decaying potato-haulms 

 when sown upon sound swedes, produced exactly the same disease 

 as was exhibited by those attacked in the pits. The conidia 

 from these sources may thus be the origin of infection for the 

 roots, hence potato-haulms, turnips, and swede tops, &c. should 

 never be left to decay on the fields but should be carefully 

 collected and burnt as soon as possible to prevent the production 

 and liberation of the conidia. 



Infection takes place most readily through a wound. There- 

 fore in preparing for store as little cut surface as possible should 

 be made, and all bruising of the roots should be avoided. 



In every case great care should be taken to ensure thorough 

 ventilation and drainage of the pits ; the roots should be pulled 



