14 
A CELERY FUNGUS. 
T. B. ROE. 
Mr. T. N. Roperts has handed to me a fungus which has 
attacked his celery plants in the Scarborough district. It is 
Septoria petrvoselint Desm. var. apit Br. et Cav., one of the 
Deuteromycetes. 
This fungus is new to Yorkshire. Although previously 
known on the Continent and in N. America, the first authentic 
record of its appearance in this country was in 1906 in South 
Devon, although there is reason to believe that it had appeared 
here still earlier. Since then it has caused much damage to 
celery both in this country and in Ireland. 
The leaves and leaf-stalks show yellowish or pale brown 
areas which later become covered with numerous minute 
black dots just distinguishable by the unaided eye, but better 
seen by the aid of a lens, and which are the perithecia or 
fruiting bodies of the fungus, these being strictly the pycnidia. 
They are somewhat globose in shape and rather flattened and 
about 200-250 p in diameter. They are amphigenous and 
sunk in the mesophyll, at first covered by the epidermis, 
just breaking through at maturity, the spores dehiscing by a 
minute apical pore, in a worm-like tendril-shaped mass. The 
spores are filiiorm, usually curved, three or more septate and 
guttulate, about 50-65 by 1.5-2, and produced in enormous 
numbers. This accounts for the rapid spread of the disease 
after it first manifests itself. The mycelium ramifies among 
the cells of the mesophyll, destroying the chlorophyll, thus 
interfering with the activities and nourishment of the plant, 
and the leaves and leaf-stalks finally wilt and die. 
Mr. Roberts informs me that last year he lost three-quarters 
of a crop of 30,000 heads of celery through this disease alone. 
This year on a different part of his land it has again made 
its appearance but not with the severity of last year’s attack ; 
still, the damage is considerable. The disease is usually 
observed about the end of July or beginning of August when, 
unfortunately, it is well established, and the damage is prac- 
tically past repair. 
As it has been proved that the ‘seed’ has been known to 
contain fruits of the fungus, washings from which have been 
made by experiment to infect healthy plants, it would be 
advisable for growers to watch their young plants, and at the 
first sign of the disease to spray them with dilute Bordeaux . 
mixture or potassium sulphide solution. As a precautionary 
measure microscopical examination of samples of ‘seed’ might 
be made, and if the fungus be detected thereon, washings in a 
fungicide might be tried, although it is possible that this would 
Naturalist 
