350 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



1. Dissolve 1 lb. of 98 per cent caustic potash in 4 gallons of water ; 

 add thereto 9 lb. of rosin, heat until complete solution is effected and 

 make up to 10 gallons by adding the necessary watei-. The brown 

 liquid so obtained is translucid (Koebele). 



2. Boil together for one hour 7 lb. of 70 per cent caustic potash, 

 25 lb. of rosin, and 3 lb. of fish oil, with 10 gallons of water. As 

 soon as the mass rises and becomes frothy, stop the boiling and make 

 up with water to 100 gallons (Coquillet). This bouillie is the classic 

 rosin bouillie of America. The followmg formula; are now in use. 

 Formula A : caustic potash, 70 per cent, 6 lb., rosin l5 lb., fish oil 

 3 lb., water 10 gallons. Formula B : caustic potash, 70 per cent, 10 lb., 

 rosin 35 lb., fish oil, 5 lb., water 10 gallons. Formula A is used in 

 summer, thinned down according to the sensitiveness of the tree, with 

 seven to nine times its weight of water. Formula B is only used in 

 winter when the sap is dormant. 



3. 16^ lb. rosin, 24^ lb. caustic potash, 98 per cent, and 24 lb. of fish 

 oil are heated together and then dissolved in 10 gallons of water. 



4. 16 lb. rosin, 4 lb. 98 per cent caustic potash, 2^ lb. of fish oil are 

 melted togethei-, and boiled in 10 gallons of water, cooled, and 4 gallons 

 of water added. Before use 1 part is diluted with 9 parts of w^ater 

 (Swingle). 



5. Dissolve 8-10 lb. of commercial rosin soap in 10 gallons of 

 water. 



Action on Plants. — Soap solutions of 0-8- 1-0 per cent strength 

 do not injure the leaves. A bouillie six times stronger than Formula A 

 used warm in December and January, resulted in the total absence of 

 flowers in the spring (Marlatt). 



Action on Insects. — Rosin emulsion acts very energeiically on 

 insects owing to its causticity ; it acts by contact and it forms besides 

 on the insect which it has drenched an impermeable coating which 

 causes asphyxia. 



Use. — Rosin bouillies are much used in America against cater- 

 pillars, and especially against cochineals ; they replace petroleum 

 emulsions. They give very good results in countries wheie the pro- 

 longed absence of rain assures the efficiency of the treatment for a long 

 period, and where the multiplication of the cochineal, owing to the 

 heat, goes on almost without interruption the whole year round. 

 Petroleum emulsions are preferable in districts w'heie rain is frequent. 

 When a resinous bouillie is used on a tree invaded by cochineal the 

 bark of the tree must, as far as possible, be entirely drenched. In 

 temperate countries two or three applications must be made at eight 

 days' interval, and preferably at the time when the mobile larvae 

 circulate in quest of a spot on which to fix themselves. The treat- 

 ments do good on deciduous trees. When the tree is much attacked 

 it must be severely pruned before spraying. To give all its efficiency 

 to the winter treatment, a dose six times stronger must be used than 

 in summer, when, on the contrary, the bouillie made from No. 2 

 formula is thinned down with nine times its volume of water. 



By this process, and with the emulsion from formula No. 4, Swingle 

 and Webber destroy the following caterpillars and lice : Ceroplastes 



