po 
VEGETABLE GARDENING 
and the potato scab gnat. Both cold and hot water are 
used in destroying plant lice, but hot water is far more 
effective. Plants will stand water heated to tempera- 
tures ranging from 125 to 180 degrees The hot water 
treatment is especially desirable to check lice on a small 
number of cabbage plants in the home garden. Pyreth- 
rum or insect powder is also effectual in destroying some 
insects by closing their breathing pores. It is generally 
used as a powder, but may also be mixed with water and 
applied as a spray. 
137. Bordeaux mixture. — Although other fungicides 
are used sometimes in vegetable gardening, this is the 
standard spray for the control of fungous diseases of 
vegetables. The usual formula is : 4 pounds of lime, 4 
pounds of copper sulphate (bluestone) and 50 gallons 
of water. 
It is convenient to keep stock solutions of both the 
bluestone and the lime. To make a stock solution of 
bluestone, use 2 pounds of bluestone to the gallon of 
water. The lime should be slaked and kept as a thin 
paste. Both solutions should be covered to prevent 
evaporation. For the formula stated, add 2 gallons of the 
bluestone solution to 25 gallons of water and then in- 
troduce the lime paste diluted with the other 25 gallons. 
When insufficient lime is used there is danger of burn- 
ing the foliage of many plants. To make certain of add- 
ing enough lime the ferrocyanide test should be em- 
ployed. This may be done as follows: Dissolve an ounce 
of potassium ferrocyanide or yellow prussiate of potash 
in a pint of water; place in a bottle and label “poison.” 
Stir lime solution into the diluted bordeaux mixture until 
the ferrocyanide solution will not turn brown when a 
drop or two is added from the bottle. It is always safer 
to have an excess of lime. As bordeaux mixture deteri- 
orates upon standing, it should be used promptly after 
mixing. 
