948 EXPERIMENT STATION RECORD. 



It was I'oiiiul that an exi>osiiiv of smut spores for 12 uiimites to a temperature 

 of 05° C. would destroy them. Further tests showed that barley would with- 

 stand a dry heat of 90° and wheat 110° without injury to germination. Where 

 grain did not contain more than the average amount of moisture it was found 

 to readily withstand a temperature of (55°, and field tests showed that barley 

 smut was entirely absent from plats the seed for which had been treated with 

 hot air. The experiments with wheat were less successful. 



Potato diseases in San Joaquin County, California, W. A. Orton ( U. 8. 

 Ifcpt. Aijr., Bur. Phuit Indus. Virc. ,i.i. pp. I.'i). — A study was made as to the 

 cause of the failure to produce successful crops of potatoes on the tule or peat 

 lands in the deltas of the San Joaquin and Sacramento rivers. These lands are 

 apparently very fertile and produce phenomenally large crops when tirst planted, 

 but in a few years the yield diminishes and the tubers become so rouf^h and 

 scabby as to be practically worthless. 



The principal cause of the trouble was found to be due to the potato wilt 

 {Fusarium oxyHporum). This disease, which has been previously noted 

 (E. S. R., 15. p. 1088), is again described and suggestions offered for its con- 

 trol. A second cause of trouble is said to be the potato scab, due to Oospora 

 scabies, while a third cause of considei'able loss is a decay of potatoes locally 

 known as " leak " or " melters." This is due to the invasion of the fungus 

 Rhizopus niffrtcans. The affected potatoes turn a dull brown outside ; the flesh 

 is buff or brown and very soft and exudes a clear brown liquid. 



For the wilt and the scab, rotation of crops, the use of resistant varieties, 

 etc.. are recommended, together with the disinfecting of the seed potatoes in 

 the case of scab, while for the trouble caused by R. )ii(/ric(inH the author sug- 

 gests care in handling the potatoes so as to prevent wounding, the practice of 

 sanitary precautions to prevent infection, and the avoidance of placing newly 

 dug potatoes in large piles where they will sweat. 



Spraying potatoes against blig'ht and the potato beetle, E. P. Sandsten 

 and J. (i. Mil, WARD {Wisvonxiii l^ta. liuJ. IdS, pp. S-27. fi(js. 13). — The Wisconsin 

 Station has been carrying on spraying trials for the past 5 years in the leading 

 potato-growing counties of the State to determine whether the early blight 

 (Alternaria sohnii), which is the only form of blight prevalent in the State, 

 can be controlled by the application of Bordeaux mixture, and also to deter- 

 mine whether spraying should be recommended as a profitable investment and 

 insurance against blight. In all. over 200 acres have been under trial as 

 described in the bulletin. 



Directions are given for the preparation and application of fungicides and 

 insecticides. A test was made of dry versus wet Bordeaux mixture, in which a 

 gain due to sjiraying with dry Bordeaux mixture of 10 bu. jier acre was ob- 

 tained as compared to a gain for the standard Bordeaux mixture of 33 bu. per 

 acre. 



For the control of the potato beetle, the authors recommend various poisons. 

 The results thus far obtained indicate that the spraying of standard late 

 varieties can be followed with an assurance of profit. Substantial increases in 

 yields were obtained from spraying early varieties which were planted late, 

 but the spraying of early varieties planted early seldom proved profitable. 



Potato spraying' experiments in 1907, F. C. Stewart, G. T. French, and 

 F. A. SiRRiNE (Xrw York State Sta. Bui. 307, pp. .'f39-.i68). — This bulletin gives 

 the results of the sixth year's work in the 10-year series of potato spraying 

 experiments which were begun in 1902. The experiments were conducted along 

 the same lines as in previous years (E. S. R., 19, p. 447), 40 separate experi- 

 ments being reported. 



