ORCHARD INSECTS OF THE PACIFIC NORTHWEST 



71 



arsenate. In this form the poison can be handled and stored readily, 

 if kept dry. Lead arsenate may be combined with oil emulsions, 

 with nicotine solutions, and with lime-sulfur or bordeaux mixture for 

 controlling various insect pests and fungous diseases at the same time. 

 If lead arsenate is combined with lime-sulfur solution, the mixture 

 should be used at once, on account of a chemical reaction which occurs. 

 This reaction may be retarded by putting casein spreader or hydrated 

 lime into the tank first, in the proportion of 1 pound to 100 gallons of 

 spray. If any residue of arsenic or lead is present on the harvested 

 fruit in quantities sufficiently great to constitute a menace to the 

 health of the consumer, it must be removed by washing or wiping 

 before the fruit is sold. 



Fluorine Compounds 



Cryolite (sodium fluoaluminate) is the most dependable fluorine 

 compound for use in replacing lead arsenate in spray schedules for 

 the codling moth. This is explained on page 8. Lime-sulfur solu- 

 tion or other materials of high lime content should not be mixed 

 with cryolite. As with lead arsenate, any excessive residue, in this case 

 of fluorine, must be removed by washing before the fruit is marketed. 



LlME-SuLFUR 



Lime-sulfur solution has many uses in controlling certain insect 

 pests and fungous diseases of fruit trees. It may be used as a dor- 

 mant spray and also, in a more dilute form, as a summer spray. In 

 the latter case it is valuable chiefly as a fungicide. The strength of 

 the concentrate varies, and should be ascertained from the manufac- 

 turer or by means of the Baume or specific-gravity scale on a lime- 

 sulfur hydrometer. The quantity of the concentrate required to make 

 100 gallons of diluted spray for various purposes is shown in table 1. 

 Dry lime-sulfur is sometimes used in order to avoid the need of trans- 

 porting the heavier liquid material. It has not proved so effective 

 against the San Jose scale as the standard lime-sulfur concentrate. 



Table 1. — Dilution of concentrated lime-sulfur solutions for various strengths of 



spray 



Strength of concentrated lime-sulfur 



Quantity ' of concentrated lime-sulfur required to 

 make 100 gallons of spray solution 



Degrees Baume 



Specific 

 gravity 



Dormant 

 strength 

 for scale 



(4H° 

 Baume) 



Dormant 

 strength 

 for blister 

 mite and 

 twig borer 



(31/2° 



Baume) 



Early 

 spring 

 strength 

 for scab 

 and red 

 spiders 



Baume) 



Spring or 

 summer 

 strength 



for mildew 

 and red 



spiders (1° 

 Baume) 



36 



1. 330 

 1.306 

 1.295 

 1.283 

 1.272 

 1.261 

 1.250 

 1.239 

 1.218 

 1.198 

 1.179 

 1.160 



Gallons 



m 



10 



lOJ-2 



11 



im 



12 

 12H 



13J,2 



1434 



16^2 



1SU 



Gallons 

 7 



7Vi 

 7% 

 8 

 8H 



8J,2 



9 

 10 



11 



12^2 



14 



Gallons 



2% 



3 



3 



3 



3 



3H 



3 1/2 



334 



m 

 m 

 5 



Gallons 



in 



34 



m 

 2 



33 



32 



2 



31 



2 



30 



2 



29 



2U 

 2Vi 



2y 2 



2% 



28 



26 



24 



22_____ 



3 



20 



3K> 







1 All quantities expressed in nearest quarter 



