18 MAINE AGRICULTURAL EXPERIMENT STATION. 



planted with seed grown on the Twin Falls, Idaho, farm. The 

 Idaho .grower goit it from a man in Carbondale, Colorado, who 

 imported the original seed from Scotland. Undoubtedly the 

 disease came all the way from Scotland to Maine with the seed 

 tubers by this round-about way, and all within five years. It 

 is a very good illustration of how some importations of infect- 

 ed seed may result in a wide distribution of a tuber-borne pota- 

 to disease in a very short time. 



Visits were made to .northern Idaho, and various parts oif 

 Oregon and Washington. Although more or less seed is grown, 

 particularly in the latter state for California planting, no es- 

 pecially large 'potato districts were visited. 



With one exception, no particularly interesting development 

 of potato diseases was observed, sufficient to require special 

 mention. Near Taeoma, Washington, at a substation of the 

 Washington Agricultural Experiment Station, was found what 

 is apparently an undescribed leaf trouble. This had already 

 been observed in 1913 and 1914 on some potatoes that bhe 

 United Stales Department of Agriculture brought to Maine 

 for some of their breeding work. I have also found a few 

 affected (plants in Maine fields this season. It is characterized 

 by a peculiar browning or streaking of the under sides of the 

 leaves or leaf petioles along the line of the veins or midrib. It 

 has been called, for the want of <a better name, the "streak dis- 

 ease." It has the appearance of a bacterial trouble, but, as yet, 

 no bacteria have been isolated from the diseased plants which 

 are capa'ble of causing the disease upon inoculation. 



Regarding California, the last state tc be taken up, I will 

 confine what I have to say to telling you something about the 

 potato industry of the deltas of the San Joaquin and Sacra- 

 mento rivers, near Stockton, the county-seat of San Joaquin 

 county. This area, sometimes spoken of as the "tule lands," 

 consists of some 250,000 acres of very fertile peat soil. 



The lands lie mostly at or near sea level and are made up 

 of the .more or less decomposed roots and decayed remains of 

 the tule or giant bulrush and other marsh plants to which has 

 been added the sediment deposited by the river. The marshes 

 are .reclaimed by throwing up levees by means of great d'redges 

 along the hanks of rivers and sloughs to exclude the tidal and 



