APPLE BLOTCH AND ITS CONTROL. 7 
6.5 u. When newly formed it is easy to demonstrate the presence of a 
gelatinous covering about the spore, especially when, as is often the 
case, it is prolonged into a stout hyaline appendage (fig. 2). The 
spores (fig. 3) germinate in 15 to 20 hours. The germ tube is some- 
what darker than the spore and 
usually shows a pronounced 
thickening at the point of emer- 
gence (fig. 3). More than one 
germ tube may issue from a single 
spore (fig. 3). 
Spores from the twig cankers 
in which the fungus has passed 
the winter are usually mature and 
ready to infect the young fruit 
and leaves about three weeks after f 
the petals have fallen. This was we. 3—Germinating spores of- Phyllo- 
first determined by Seott and sticta solitaria. Ronee from Ben Davis 
Rorer by noting the latest time Er aati te ona 
at which spraying would effectively prevent infection. The time of 
infection was directly determined by the writer during the seasons 
of 1914 and 1915 by germination tests of spores from twig cankers. 
Table I shows the results of such tests. 
TABLE I.—Results of germination tests of spores of apple blotch from twig 
cankers. 
Germi- Germi- Germi- 
Date. nating Date. nating Date. nating 
spores. spores. spores. 
1914. Per cent. 1914. Per cent. 1915. Per cent. 
ADT SO Ree le heel 0 yg ea i Ce ORI MayalSeene ei tge lee 10 
Mayle tho as ee OF May 212 Sse Wien 2 Nee oonoconSamcae 20 
May (GEeS sah ae ote Os Miaye23 eo ees Us WR W APs Sesodooucsoe 20 
Maye Se iesges 2 teks OEE Miaya2oasee ae ssh ead eee CRBS A Wed ean OX Lo ree eee 75 
IME yp: 9 rms Seahee ape Se iy tS PAW IME A SeaaobscosoegEce US ||| MEN PISooesaoanosesleee 75 
For each test, pycnidia were scraped from the newer portions (the 
current year’s growth) of young twig cankers. These pycnidia were 
then examined under the microscope for spores. If spores were sufli- 
ciently abundant and appeared to be mature, they were suspended in 
distilled water in Van Tieghem cells and the percentage of germinat- 
ing spores was noted daily for periods ranging from three to five 
days. As the spores when mature usually germinate within 24 hours, 
it was really unnecessary to prolong the attempted germination over 
so long a period. The cankered twigs used in this work in 1915 were 
collected from the same trees as those used in 1914. 
During both seasons the time of petal fall was April 28. As these 
two seasons were about average ones, it is evident that in the Ozarks 
