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Joumal of Agricultural Research 
Vol. XXVIII, No. 4 
(fig. 6), that on Aroma berries during the later period of rainy weather, May 22 
to 27, leather rot increased after the rain and that as it inpreased other rots 
decreased. Owing to press of other work, the first count on the two tests had 
to be postponed until about 30 hours after removal of the fruit from storage. 
Percentage of all rots is therefore excessively high, and not strictly comparable 
with the percentage found when counts were made immediately after removal 
from storage. Reference to figure 6 and Table VIII, May 23 and 26, shows 
nevertheless that on both of these dates, rots other than that caused by Phytoph- 
thora constituted a much larger proportion of the total rot, on the variety 
Aroma, than they did during the preceding week on the variety Klondike. But 
according to evidence already adduced, the rainfall from May 22 to 27 was 
very favorable for the development of leather rot. The obvious explanation, 
and one which is supported by observations and counts made in the field, is that 
the variety Aroma is less susceptible than the variety Klondike to leather rot. 
In the field. —Incomplete data on occurrence of the various rots in the field 
are given in Table VIII. These figures indicate that under field conditions there 
is for both Aroma and Klondike, a progressive increase in Phytophthora rot as the 
season advances and a corresponding decrease in other rots; for Aroma, a 
preponderance of “other rots” over leather rot about as great as that noted in 
the holding tests. 
Table VIII.— Percentage of ( 1) leather rot, (2) other rots, occurring in strawberry 
fruits infields, near Beebe, Ark., May, 1923* 
Date 
Leather 
rot 
Other 
rots 
Variety 
May 8..... ........ 
19.1 
80.9 
Klondike. 
May 9. ..... _ . .... .. 
26.6 
73.4 
Do. 
May 15__.......... 
88.4 
11.6 
Do. 
May 16........... 
91.2 
8.8 
Do. 
May 25............. 
14.8 
85.2 
Aroma. 
May 26........ 
35.0 
65.0 
Do. 
May 28__........ 
55.0 
45.0 
Do. 
a Percentages calculated on the basis of total rot as 100 per cent. 
Table IX.— Percentage of (1) sound, and {2) rotten strawberries in fields near 
Beebe, Ark., May, 1922 
Date 
Sound 
Rotten 
Variety 
May 8........ . 
Per cent 
62 
Per cent 
38 
Klondike. 
May 9....... 
82 
18 
Do. 
May 16....... 
90 
10 
Do. 
May 18............ 
76 
24 
Do. 
May 25.... . „„ , 
60 
40 
Aroma, 
May 26.... . 
25 
75 
Do. 
May 29 «. 
33 
67 
Do. 
° The figures for May 29 are the average of an estimate, by three competent observers, of the loss from rot 
on May 28 and 29 in the district immediately surrounding Beebe; all other figures in the table are based 
on field counts made on the date opposite which they are entered. 
RELATION OF STRAWBERRY PHYTOPHTHORA TO TEMPERATURE 
IN LABORATORY EXPERIMENTS AND IN HOLDING TESTS 
In laboratory experiments. —The effect of various temperatures on the 
growth of the fungus (in culture) was tested by holding sets of three plates (of 
potato dextrose agar) inoculated with the organism, in each of nine compartments 
of an Altmann constant temperature apparatus. At the end of 10 days the plates 
were removed and the diameter of the growth was measured. Results of one 
such experiment gave the following results: 
