TWENTY-SIXTH SESSION. 
47 
Time— A. M. 
Exposed 
thermometer. 
Whitened twig. 
Natural twig. 
Weather conditions. 
Time— P. M. 
Exposed 
thermometer. 
Whitened twig. 
Natural twig. 
Weather conditions.. 
7.... 
35° 
33° 
33° 
Cloudy. 
1.... 
63° 
60° 
72° 
Clear. 
8 .... 
47° 
38° 
41° 
Hazy. 
2.... 
61° 
60° 
71° 
Slight haze. 
8 .... 
55° 
48° 
55° 
Slight haze. 
3.... 
63° 
60° 
75° 
Clear, sunny. 
10.... 
56° 
51° 
64° 
Clear, sunny. 
4.... 
58° 
55° 
68° 
Clear, sunny. 
11.... 
59° 
54° 
69° 
Clear, sunny. 
5.... 
47° 
48° 
50° 
Haze. 
12.... 
64° 
59° 
73°. 
Clear, sunny. 
6 .... 
i 48° 
46°' 
46° 
Sundown. 
Reference to the table will .show that during very bright sunlight at mid- 
day the natural twigs were 15 degrees warmer than the whitened twigs. The 
whitened twigs were of nearly the same temperature as the atmosphere. 
When the sun came out suddenly bright, however, the whitened twig did not 
warm up so rapidly as did the atmosphere. This difference of 15 degrees 
in temperature explains why natural twigs may swell perceptibly on warm 
days in winter, when whitened twigs do not swell enough to endanger them- 
selves to subsequent injury from cold. 
Oomparison showed that naturally light colored twigs do not absorb so 
much heat as the dark purple twigs. Varieties of the “Snow” type do not 
reach so high a temperature by several degrees as . do varieties that have 
darker twigs. 
Whether or not whitening will prove commercially profitable remains for 
the practical grower to work out. Its profitableness will no doubt depend 
largely upon climatic conditions. In districts where there is an intensely 
bright winter sunlight it will probably have greater value than in districts 
where the winters are more cloud y. Where winter rains are abundant they 
may too frequently wash off the lime, rendering frequent application expen- 
sive. It is not improbable, however, that a wash may be discovered that will' 
stick more effectively, rendering repeated application unnecessary. 
The fact that light green twigs absorb less heat than purple ones suggests 
the advisability of selecting for light twigs, in originating new varieties for 
those regions where whitening has a beneficial effect. 
The President invited discussion. 
Mr. M. S. Cook, Pennsylvania, said that in his experience with whitewash- 
ing he had found that by the addition of a pound of pulverized glue, adding, 
the slackened lime, the whitewash would stick very well. 
Mr. H. J. Webber, Washington, D. C., remarked that possibly Prof. Whit- 
ten might cheapen his process by combining the whitewash spray with the. 
fungicide, Bordeaux mixture, which of course is used foi\the monilia or rot 
of the peach. He inquired whether the addition of the blue vitriol would 
make the whitewash too dark in color to answer the purpose intended. 
Prof. W T hitten replied that, in his experiments, blue vitriol had been tried 
in the wash and it had been found that it could be used 'in sufficient quantity 
to answer the purpose of the fungicide without detracting from its effect in 
reflecting the heat. The additional result had been shown that even the pure 
lime, without the blue vitriol, would almost entirely prevent leaf curl 
but he was not able to say what would be its effect upon monilia. The 
amount of blue vitriol used was about six pounds to fifty gallons of white- 
