F. J. Chittenden 205 



mitigated the severity of the attack i, and in some cases proved a perfect 

 cure. 



When the paper on " Celery Leaf-Spot " appeared we were in pos- 

 session of the knowledge that the disease was due to the fungus Seporia 

 pefroselini var. apii B. and C, that it was spreading rapidly and in a 

 fashion that could best be explained on the assumption that the seed 

 carried infection, that the " seed^ " frequently showed the fruits of 

 the fungus, that these fruits contained spores capable of germinating, 

 and that plants sprayed with water containing these spores succumbed 

 to the disease, but the actual infection of the seedlings from infected 

 seeds had not been observed. We have recently been able to demon- 

 strate this infection and to place this on record is the object of this 

 note. 



Seed showing the fungus fruits containing spores was sown in the 

 ordinary way and the germination kept under observation. It was 

 found that in many cases the pericarp remained attached to the coty- 

 ledons for a considerable time after they emerged from the soil and 

 became green, and that many of the cotyledons turned yellow owing 

 to the attack of the fungus which quickly produced fruit containing 

 the typical spores. Only those seedlings which had grown from seed 

 showing the fungus were "attacked at this time and the pieces of peri- 

 carp attached to the diseased cotyledons showed the fungus quite clearly. 

 Side by side with the diseased seedlings were others which were at this 

 stage perfectly free from attack and which were developed from healthy 

 seed. The chain of evidence that the seed carries the infection is there- 

 fore complete. 



Whether there are any other modes by which the fungus maintains 

 its infective powers from season to season, as, e.g. on diseased portions 

 of plants thrown on the rubbish heap or dug into the ground, is not 

 clear, but it is clearly a point of economic importance that seed-growers 

 should take every care to save seed only from healthy plants. If this 

 were consistently done the author feels sure it would do much to mitigate 

 the severity of the attacks and it would probably result in stamping 

 out the disease entirely. 



The disease appears to spread more slowly during the seedling stage 

 than later in the season and the attack is more localised on the plant. 

 Diseased plants in September usually show the fruits of the fungus 



^ See for instance Salmon, E., in Gard. Citron. 1913. 



^ It ought perhaps to be noted that the commercial celery " seed " really consists of 

 fruits or half fruits and therefore carries parts of the parent plant readily open to attack. 



