218 REPORT OF THE HORTICULTURAL DEPARTMENT OF THE 
are injured more than others; the injury is sometimes most severe 
on the fruit and sometimes on the foliage; the fruit alone of some 
varieties is immune and of others, the foliage; the injury may 
appear in a few days or may not show for several weeks after 
spraying; and a very weak mixture may cause greater injury than 
a stronger one used under similar conditions. 
7. Injury on the fruit first appears as small, round, black or 
brown specks. Later, the injured specimens become rough and 
russeted because of a ruptured epidermis and layers of dead corky 
cells. Badly injured specimens are always more or less distorted 
through shrinkage of the injured portions, by teat-like malforma- 
tions, or by rough, sunken scars. 
8. Injured apples do not keep well. ‘Their season in cold storage 
is not greatly shortened but when the fruit is exposed to the air 
the affected parts become mealy, decay sets in quickly, and the 
flesh becomes soft and flabby. 
g. A microscopic examination of injured fruits shows that the 
waxy covering and the cuticle proper have been largely destroyed. : 
Such of the epidermal cells as remain and those of the fruit flesh 
which are injured, have much thickened walls of a brown, corky 
appearance. 3 
10. Affected leaves first show dead, brown spots of various 
shapes and sizes. Quickly following the appearance of these spots 
the leaf tissues turn yellow and the leaves fall. When the injury 
is slight the yellowing may not appear nor the leaves drop. | 
11. Bordeaux mixture has a particularly harmful effect on the 
apple blossom, killing the tissues of the floral organs. 
12. Injuries from the arsenites, frost, fungi, work of blister 
mites, lens action of drops of water, and from lime, are somewhat 
similar to bordeaux injury and are often confused with it. 
13. Some varieties of apples are injured much less than others 
by bordeaux mixture and there is a wide range in this variation. 
Immunity to bordeaux injury does not correspond with immunity 
to the apple scab fungus. 
14. The chemistry of bordeaux mixture, though seemingly simple, 
is somewhat complex. The compounds formed vary greatly with 
the proportions of the ingredients used and the conditions: under 
which the mixture is made. The mixture changes greatly under 
the influence of weather and especially of moisture in meteoric 
form. : 
15. [Theories as to the toxic action of bordeaux mixture may 
be grouped into two classes: (1) The mixture is acted upon by 
