THE BORDEAUX MIXTURE 489 



This is safe to use on foliage. It may be used much stronger when 

 trees are dormant as strong as ten pounds of lime and ten pounds of 

 bluestone to fortyi gallons of water to kill spores of fungi on the bark, 

 but the chief advantage of the stronger mixture is not directly in spore- 

 killing but in the longer resistance to removal by rains, ^his winter 

 treatment is a successful preventive of curl-leaf on the peach, shot-hole 

 on the apricot, scab on the apple and pear, rust on the prune, etc. In 

 the case of the peach blight, which is an invasion of the young bark 

 by the shot-hole fungus, an autumn spraying is imperative to protect 

 the dormant twigs.* When the fungus survives winter treatment or 

 when it attacks the fruit, as in case of the apricot particularly, or the 

 leaf in the peach, there should follow the weaker Bordeaux in the 

 spring or summer, as early as indications of the diseases may appear. 

 In spraying for apple and pear scab, the addition of five pounds of 

 lead arsenate to each one hundred gallons of the Bordeaux Mixture 

 makes the application answer also for the codlin moth, as described 

 in the preceding chapter. 



When it is desirable to use a fungicide on fruit near the picking 

 season, or on ornamental plants, which would be disfigured with the 

 lime wash, the ammonical copper carbonate may be submitted for the 

 Bordeaux Mixture, viz. : Copper carbonate, four ounces ; ammonia, 

 forty ounces ; water forty gallons. 



The usual way of making this wash is to dissolve copper carbonate 

 in ammonia, and then dilute. If the carbonate is not fully dissolved 

 before the water is added, it can not be further dissolved, and not 

 only is the carbonate wasted, but the fluid will not be up to standard 

 strength. It is well, therefore, to give the ammonia ample time to act, 

 say over night, before adding the water. 



The lime, salt and sulphur mixture, as already prescribed for scale 

 insects in the preceding chapter, is an active fungicide for winter use. 

 It is sometimes a satisfactory curl-leaf preventive in the interior valleys 

 especially. 



Toadstool Destruction. Trees are often destroyed through in- 

 vasion by toadstool fungi from the decaying roots or wood with which 

 their roots come in contact. The injury is often not detected until the 

 tree is ruined and it is too late for treatment. If only part is affected, 

 the disease may sometimes be arrested by cutting away the diseased 

 parts and disinfection of the exposed tissue with Bordeaux Mixture. 

 Stone fruits are most susceptible to this trouble, the cherry being least 

 affected. Young apples are sometimes attacked, but mature trees resist 

 it. Pears and figs are also largely resistant. 



Moss, Lichens, etc., on the Bark. It has been clearly shown by 

 investigation at the University Experiment Station that the growth of 

 moss, etc., upon the bark of fruit trees is a decided injury. All trees 

 should be assisted to maintain clean, healthy bark. This is accomplished 

 by the use of the lime, salt and sulphur mixture already prescribed for 

 scale insects. It can also be done by winter spraying with caustic soda 

 or potash, one pound to six gallons of water. 



'Consult Bulletin 191 of the University Experiment Station on "California Peach Blight." 



