THE MONTHLY BULLETIN. 369 



NOTES ON THE POTATO SITUATION IN THE DELTA. 



DISEASES. 



By N. V. Shear, U. S. Department of Agriculture, Middle Island, Cal. 



Inasmuch as there seems to be a desire on the part of those interested 

 in the potato situation in the delta for a better understanding of some 

 of the troubles which have been causing a decrease in the yield of this 

 crop, I take this opportunity of explaining the situation. 



The delta district comprises a large area of very fertile soil. The 

 fertility of the soil, combined with the ease with which it can be 

 irrigated, makes it admirably adapted for the production of large 

 crops of potatoes; and it is due to these natural advantages and the 

 energy of the people who have reclaimed it from the waters of the 

 San Joaquin and Sacramento rivers that it is today one of the greatest 

 potato growing sections within such a restricted area in the United 

 States, if not in the world. There is no other locality in this country, 

 and perhaps not in any other country, where such large areas of 

 potatoes can be seen growing at one time within the radius of a single 

 sweep of the eye. 



This industry has now been carried on for a considerable number of 

 years with great profit to the individuals engaged in it and to the 

 community at large. The large crops of potatoes which have been 

 and still are being grown in this locality have been due not only to 

 its fertile soil and ease of irrigation, but also to the fact that many 

 potato diseases and insect pests which have reduced the yields of 

 potatoes in most other sections of the United States are either not 

 present in the delta or may be considered a negligible factor in this 

 industry. One notable example of this freedom from potato pests is 

 the absence of the potato beetle. Throughout the greater portion of 

 the potato growing sections of the United States east of the Rocky 

 Mountains the potato vines need to be sprayed several times during 

 the season to kill the larvae of the potato beetle. The flea beetle is 

 another insect which at times causes considerable damage to the vines 

 in a great many localities, but which, so far as the writer's observation 

 goes, does little damage in the delta. 



With reference to fungous diseases of the vines the potato grower 

 in the delta has a great advantage over most other potato producing 

 sections. The late blight, a disease which has at times wiped out 

 almost the entire crop in Ireland, and hence is sometimes called the 

 "Irish blight," is also very destructive to the potato crop in many 

 portions of the United States, but in the delta is seldom seen and does 

 little or no damage. The same statement may be made with reference 

 to the early blight, which is a fungous disease of the potato vines and 

 which causes considerable loss in many parts of this country, but which 

 injures the crop in the delta but very slightly. 



Owing to the absence of the above mentioned troubles, all of which 

 injure the vines above ground, it is not necessary for the potato grower 

 in the delta to spray his crop during the growing season. Many 

 thousands of dollars are spent every year throughout the United States 

 in spraying potato vines to prevent injury by one or all of the diseases 

 mentioned above, viz: Potato beetles, flea beetles, early blight, and 

 late blight. 



