THE MONTHLY BULLETIN. 371 



In some sections on dry land where little water is used for irrigation 

 this insect has proven a serious pest to potato growers. From the 

 ex})eiMence the delta people have had with this insect it does not seem 

 probable that it will produce serious injury to marketable tubers in 

 this section. Probably because of the great amount of water used for 

 irrigation the larvae of the tuber moth do not find their way into the 

 tubers below ground to any great extent. 



Those interested in potato growing in the delta should become 

 familiar with the causes which are at work in decreasing the potato 

 production in this important section of the state, and it is evident that 

 this must precede any adequate effort toward a betterment of the 

 situation. The potato industry of the delta, like any other agricultural 

 industry of the State, whether it is the growing of pears, oranges, 

 grapes, or nuts, in order to be placed upon a permanent footing, must 

 be made a matter of study to learn the factors which are at work 

 controlling the crop, and then the proper measures must be put in 

 operation to keep the industry upon a profitable footing. 



NOTE. 



In view of the emergency Potato Convention to be held in Stockton 

 September 25th and 26th, the above article from Mr. N. V. Shear is 

 very timely. Mr. Shear is doing telling work at the station at Middle 

 Island in the great delta region along the Sacramento and San Joaquin 

 rivers. The importance and magnitude of the investigations which 

 he is carrying on warrant more assistance at this station. This phase 

 of the situation should receive careful consideration at the Stockton 

 convention, in the hope that we may still further increase the useful- 

 ness of the station at ]\Iiddle Island. — A. J. Cook. 



CITRUS CANKER. 



This is a serious citrus scourge, fungoid in nature, which attacks 

 all kinds of citrus trees except kumquats. Pomeloes suffer most. The 

 disease attacks twigs, leaves and fruit. Prof. E. W. Berger of Florida, 

 who has studied this disease thoroughly, says "it requires no extensive 

 mathematical knowledge to discern that this disease may cause losses 

 aggregating millions of dollars if not eradicated. ' ' Prof. Berger finds 

 it in Florida, Alabama, Mississippi, and Texas, and thinks it may exist 

 in Louisiana. It was introduced from Japan and in the Gulf States 

 it is most abundant in Texas. Our quarantine against citrus from 

 the Gulf States because of the white fly, and against fruit because of 

 melanose, will serve a further purpose in barring out this new enemy. 

 Our thorough quarantine and inspection of Japan citrus will help to 

 keep the disease from coming to us from the far off Orient. — A. J. Cook. 



NEW HOST OF POTATO EELWORM. 



Word conies from the Kansas Agricultural College that the Canada 

 thistle Cirsium arvensis is one of the many host plants of the potato 

 eelworm Heterodera radicicola. Fortunately this serious weed pest is 

 not common in California. Here is another reason for extermination 

 where it now occurs, and for keeping it from further introduction. — 

 A. J. Cook. 



