Some Tomato Diseases. F. T. Brooks and G, O. Searle. 181 
MACROSCOPIC CHARACTERS OF THE VARIOUS FORMS ON 
DOX’S MEDIUM MODIFIED TO CONTAIN 7:5 GRMS. CANE 
SUGAR PER LITRE, WITH OCCASIONAL NOTES ON CHAR- 
ACTERISTICS SHOWN BY THE FORMS ON OTHER MEDIA. 
Form A. Aerial mycelium fairly plentiful, varying from white 
to grey. Medium not coloured, submerged mycelium hyaline. 
Pycnidia very numerous, black, small, more closely aggregated 
towards the middle of the culture, semi-erumpent. No visible 
spore mass. This form generally produced pycnidia very 
sparingly. The quantity of mycelium varied greatly on different 
media; on potato agar it was very slight with a few light brown 
pycnidia, whilst on Dox’s medium with 30 grms. sugar per 
litre, the mycelium was very profuse and dark olive green in 
colour. 
Form B. Aerial mycelium fairly plentiful, generally white 
but varying to light grey in colour, submerged mycelium 
hyaline. Pycnidia numerous, scattered, varying greatly in size, 
generally in the aerial mycelium, sometimes on the surface of 
the medium, black in colour. With potato agar, on the other 
hand, the mycelium was dark coloured and largely submerged 
in the medium, and numerous dark coloured appressoria were 
formed towards the edge of the culture; on tomato agar a dirty 
yellow-coloured spore mass was noticeable and on Dox’s 
medium with 30 grms. sugar the mycelium was very profuse 
and almost black. 
Form C, Aerial mycelium very slight, fulvous brown to grey. 
Pycnidia very numerous, chocolate brown in colour with a few 
pink spore masses. Pycnidia apparently seated on the surface 
of the medium. On Dox’s medium with 15 grms. sugar per 
litre, the spore masses were very conspicuous as pink spots 
which coalesced all over the surface of the medium, whilst at 
the top and bottom of the culture were dark brown bands of 
aerial mycelium bearing the Alternaria form of spores; on 
potato agar, on the other hand, both mycelium and pycnidia 
were scanty, the latter being light brown in colour and almost 
entirely aggregated along the original inoculation streak. All 
the cultures were similar in showing scanty mycelial growth and 
early formation of pycnidia, the first being usually formed 
within 48 hours of the culture being made. The Alternaria 
form invariably appeared later and upon the drier portion of 
the culture. Sowings of the Alternaria spores were made and 
these produced pycnidia first and Alternaria later. Cultures 
made from single pycnospores also formed spores of Alternaria 
as well as pycnidia. 
Form D. Aerial mycelium grey, tending to become matted. 
M.S. 12 
