250 



CALIFORNIA FRUITS: HOW TO GROW THEM 



where, others curl in one place and not in another, others are prac- 

 tically* free from curl in all situations. 



Curl-leaf occurs in various degrees. Mild cases do not seem to 

 injure either tree or fruit; severe cases destroy the fruit and some- 

 times the tree itself. The disease is almost always at its height 

 when the young fruit is about the size of small peas. If the curl is 

 "bad," the fruit will fall to the ground, there not being healthy 

 leaves enough to afford the required support. If, however, the 

 curl is moderate and partial, only a part and sometimes none of the 

 fruit will be lost. The disease, as is well known, is of brief duration, 

 say twelve to twenty days, after which the tree resumes a healthy 

 appearance in every respect, and if the fruit has been able to sur- 

 vive the ordeal, it also appears to grow and become as perfect as if 

 no check had been given to its growth. But it is better to save the 

 tree the burden of a new foliage growth. 



Mildew. This disease, which occurs in the form of whitish 

 felted patches on leaf and twig early in the spring, and finally af- 

 fects the fruit, has long been troublesome in this State, and occurs 

 on certain susceptible varieties in many localities from the coast to 

 the Sierra foothills. Observation in this State has fully affirmed 

 the statement of Downing, that the serrate, glandless-leaved varie- 

 ties are liable, and those with good glands on the leaf stems are free. 



The conclusion would be that where mildew prevails, varieties 

 with serrate, glandless leaves should be avoided. But it has been 

 found that some glandless-leaved varieties, although subject to mil- 

 dew, resist curl-leaf. Therefore it may be worth while to combat 

 the mildew. This has been done effectually by treatment which will 

 be described in a later chapter. 



As with curl-leaf, mildew is prevalent some years and slight in 

 others. 



Peach Blight. The most serious disease which has thus far 

 stricken the peach in California is locally known as the "peach 

 blight," the work of a shot-hole fungus (coryneum). This also has 

 been satisfactorily checked by spraying, as will be described in the 

 Chapter on Diseases of Trees and Vines. 



Split-Pit A common trouble of the peach known as "split-pit," 

 has recently been studied by the California Experiment Station and 

 the tentative conclusion has been reached that split-pits are psysio- 

 logical phenomena and not caused by disease germs. Whether this 

 abnormal growth is due to weakness of variety or to cultural condi- 

 tions is not determined. It is true that varieties differ in amount 

 of splitting, and selection is being made to some extent on that 

 basis. 



Insects infesting the peach are discussed in Chapter XLI. 



VARIETIES OF THE PEACH 



Nearly all varieties of the peach have been tried in California, 

 and, as with other fruits, it has been found that varieties must be 

 chosen with reference to their success in special locations. Choice 



