The occurrence of physiologic races of
Phytophthora fragariae is demonstrated. A comparison
is made of the size of sporangia, zoospores and
oospores produced by them, and the temperature
relations of the races are determined.
The differential response to red core of five
varieties of strawberry, namely, Huxley,
Oberschlesien, Auchincruive 6, Auchincruive Climax
and Auchincruive 11 is studied.
The conditions governing the germination of
the oospores are investigated.