1088 EXPERIMENT STATION RECORD. 



aryonioal mixturo produced a gain of 124 Ini. per acre. The addition of Bug Death 

 and Paris green to the Bordeaux mixture was api)arently without much effect on 

 account of tlie unusually small nundiers of potato beetles and other insects. Neither 

 Paris green nor Bug Death have any value in controlling potato blight, the Bordeaux 

 mixture alone being quite effective. 



Experiments were carried on for the purpose of determining the relation between 

 the date of digging potatoes and development of the rot. Four rows of potatoes 

 were dug on each of 5 days, that is, August 31, September 7, 14, 21, and 28. All of 

 the potatoes were stored under similar conditions. The results indicated that when- 

 ever there is danger of rot it is best to delay digging the potatoes for 10 or more days 

 after the tops die. 



A test of sprinkling potatoes with air-slaked lime before placing them in the cellar 

 showed that this method is of no value in controlling the develoj^nent of the rot. 



In experiments with potato scab it was found that corrosive sublimate and forma- 

 lin were equally efficient. The formaldehyde gas treatment, however, is recom- 

 mended as preferable for this purpose. An air-tight room is required, and it is 

 recommended that not less than one pound of formalin be used for each 1,000 cu. ft. 

 of space. 



The dry rot of potatoes due to Fusarium oxysporum, E. F. Smith and D. B. 

 Swingle ( U. S. Dept. Agr., Bureau of Plant Indmtry Bui. 55, j)P- ^4, pis. 8, figs, f ) . — 

 This disease of jiotatoes has long been recognized in the United States and foreign 

 countries under various names, such as bundle Ijlackening, dry end rot, etc. The 

 authors made a study of the morphological and biological characters of the fungus, 

 the methods of infection, and remedial measures. 



The disease commonly enters the plants through the roots and slowly spreads 

 until the whole underground portion of the plant is infected. In infected plants 

 the fungus is always present in the darkened fibrovascular bundles of the tubers. 

 The symptoms of infection are a slow change of color, the checking of growth, and 

 slight curling of the leaves, followed by wilting and falling of the stems. The fun- 

 gus grows readily in a considerable variety of culture media and tolerates compara- 

 tively large amounts of malic, citric, and tartaric acids. It is checked in growth, 

 however, by formic, acetic, and butyric acids. The fungus is aerobic and grows 

 most vigorously at temperatures between 15 and 30° C. 



Dry rot attacks potatoes from the soil, and winters over in infected plants. The 

 use of fertilizers, even in large amounts, failed to check the development of the dis- 

 ease. The fungus persists in stored potatoes, whether kept in moist or dry rooms, 

 unless a low temperature is maintained. 



It is recommended that infected land be planted to other crops for a number of 

 years, and that the possibility of the disease infecting tomatoes, eggplants, and pep- 

 pers be kept in mind. Great care should l)e exercised in the choice of seed tubers. 

 Some difference in the resisting power of different potato plants to disease was noted, 

 and further investigations will be conducted to determine whether highly resistant 

 varieties may be developed. 



Spraying fruit trees, E. P. Sandsten( Wisconsin Sta. Bui. 110, pp. 28, figs. 12). — 

 The author discusses in a general manner the method of preparing and applying 

 insecticides and fungicides and presents notes on the more important insect enemies 

 and fungus diseases of fruit trees. 



Spraying grapes for black rot in Erie County, Pa., G. C. Butz {Pennsylvania 

 Sta. Bui. 66, pp. 16, j)ls. 2, map 1). — During the season of 1902 the vineyards of the 

 Chautauqua grape belt were greatly injured by the attack of black rot. The disease 

 was investigated by the station and arrangements were made to supervise experiments ' 

 which were carried out by vineyardists. The Concord variety is grown almost 

 exclusively in this region. The fungicide used in these experiments was Bordeaux 

 mixture in the 4-6-50, 4-4-50, and 3-6-50 proportions. In some cases ^mmoniacal 

 solutions of copper carbonate were used for later applications. 



