370 
Joumal of Agricultural Research 
Vol. XXVIII, No. 4 
The rot percentages are entered, on figure 6, not for the day on which the 
first counts were made but for the day on which the fruit was picked; they ac¬ 
tually represent the rot which had developed four days after picking. The most 
striking portion of the chart is that which covers holding tests with Klondike 
strawberries for the period from May 14 to May 21, inclusive; during the first 
two days of that period there was heavy rainfall—on the 14th, 1.20 inches; on 
the 15th, 2.40—and on the remaining four days no rain at all. The temperature 
for the six days, as recorded at Little Rock, ranged from 68 to 83° F. for the 
maximum and from 50 to 65° F. for the minimum, with the higher readings 
coming in the latter half of the period. General notes on weather show that 
four of the days were cloudy, two clear. 
Weather notes , Beebe , A%k., from May 5 to May 31, inclusive 
May 5—Cloudy. 
May 6—Clear. 
May 7—Rain forenoon, partly clear 
afternoon. 
May 8—Partly cloudy. 
May 9—Clear. 
May 10—Clear, south wind. 
May 11—Cloudy. 
May 12—Cloudy, rain afternoon. 
May 13—Clear; north wind; rain at 
night. 
May 14—Cloudy. 
May 15—Cloudy. 
May 16—Cloudy. 
May 17—Partly cloudy. 
May 18—Clear. 
May 19—Clear. 
May 20—Clear. 
May 21—Partly cloudy; rain at night. 
May 22—Partly cloudy; rain at night. 
May 23—Partly cloudy; warm in after¬ 
noon. 
May 24—Cloudy, showers. 
May 25—Cloudy, showers. 
May 26—Cloudy, rain afternoon. 
May 27—Clear. 
May 28—Clear. 
May 29—Mostly cloudy. 
May 30—Clear, rained late afternoon; 
picking practically stopped. 
May 31—Clear. 
It is apparent that during these six days there was excellent opportunity for 
determining what correlation, if any, exists between rainfall and leather rot of 
strawberries. Reference to the chart shows that in this instance positive corre¬ 
lation does exist. For fruit picked on the 14th and 15th, the days when the 
rain occurred, the percentage of rot was about what it had been during the previ¬ 
ous 10 days. (This statement is based partly on what shows on the chart and 
partly on field observations and counts.) But for the fruit picked on the 16th 
and counted four days later the percentage of rot rose to 29.2 per cent, on the 
17th to 45.4 per cent, and on the 18th, four days after the first rain, to a maxi¬ 
mum of 68.5 per cent; on the 19th it dropped back to 10.9 per cent and on the 
21 st to 6.2 per cent. (Compare 3 per cent on the 9th and 4 per cent on the 15th.) 
This course of events is practically that observed in inoculation experiments, 
where the first visible symptoms of leather rot appeared on the third day after 
inoculation and fully developed rot on the fourth. It also helps to explain re¬ 
ports by representatives of the Federal Market News Service, by receivers on 
the markets, and by the sales manager of the local association at Beebe that 
Klondike berries picked and shipped on the 18th showed more loss on arrival at 
market than did those shipped on any other day from the 14th to the 21st. 
The marked drop in rot from 68.5 per cent on the 18th to 10.9 on the 19th and 
6.2 on the 21st is best explained by assuming that very little infection occurred 
after the 15th, the last day of rainy weather. It is exactly what should be ex¬ 
pected if Phytophthora infection occurs only in wet weather and takes three to 
four days to become visible rot. If, however, there had been rains for several 
days or only two or three days apart, the attacks would have so overlapped as 
