652 REPORT OF THE, HORTICULTURIST OF THE, 
in this climate, but appears to result from the spray under unta- 
vorable weather conditions, the period of injury varying to early 
or late as these conditions vary. 
7. Varieties of apples or pears noted on the preceding pages, 
671 and 675, as injured badly or very badly by the spray should 
not be sprayed after a prolonged period of rainy weather. It is 
then better to risk injury from insects and fungi than to risk 
injury from the spray. 
8. Varieties not referred to in the preceding paragraph if they 
are subject to injury from codlin moth or scab fungus should be 
sprayed three times even though the weather conditions have 
been very unfavorable. Although they may be injured some- 
what by the spray the yield of first-class fruit will be very much 
increased by the treatment. 
9. The three treatments which have successfully prevented 
injury from the scab fungus in pear orchards have been found 
equally successful in preventing injury from the scab fungus in 
apple orcnards. 
10. In selecting varieties of either apples or pears for planting 
in commercial orchards their susceptibility both to the attacks of 
the scab fungi and the injury from spraying under unfavorable 
weather conditions should be carefully considered. 
11. It is desirable that a simple expression for denoting the 
strength of Bordeaux mixture come into general use. An ex- 
pression is advocated which states first the unit of weight for the 
copper sulphate and then the measure of the Bordeaux mixture 
formed with this amount of copper sulphate. See page 649. 
12. The potassiwm ferrocyanide test furnishes a very conveni- 
ent method of preparing Bordeaux mixture without weighing the ~ 
lime. By its use one part of copper may be detected in about 
four hundred thousand parts of solution. Its reliability is shown 
by the many times it has been used without injurious results. 
The potassium Iodide and starch paste test and potassium wanthate 
test are used in a similar manner and are even more delicate tests 
than the potassium ferrocyanide. 
13. In using the potassium ferrocyanide test, or other color 
tests, for preparation of Bordeaux mixture it is best to add a little 
more lime after the test shows no further change of color, thus 

