834 EXPERIMENT STATION RECORD. [Vol. 37 



jpct read before the Royal Horticultural Society, London, on September 12, 

 1916. 



A bibliography of cited literature is appended. 



Viticulture, P. Pacottet {Viticulture. Paris: J. B. BaiUidre d Rons, 1917, S. 

 cd., rev. and enl., pp. 554, fiff^- 217). — This is one of the volumes of the Encyclo- 

 p^die Agricole, published under the direction of G. Wery. 



The introductory chapter contains a brief survey of the genus Yitis. Succeed- 

 ing chapters deal with the anatomy and physiology of the grape, factors influ- 

 encing quality and production, the viticultural jieography of France and foreign 

 countries, the details of grape growing, ampelography and reconstitution of 

 vineyards, and the maladies and enemies of the grape. 



Citrus culture in Japan, China, and Formosa, C. P. Clausen {Mo. But. Com. 

 Hort. Cah, G {1917), No. 10, pp. 379-3S3, flgx. 3).— A brief account of cultural 

 methods employed in Japan, China, and Formosa. 



Some abnormal water relations in citrus trees of the arid Southwest and 

 their possible significance, R. W. Hodgson {Univ. Cat. Pubs. Agr. Sci., S 

 {1917), No. S, pp. 37-54, pl- h fid^- 2). — This paper deals with one phase of the 

 investigation of a so-called physiological disease, June drop of the Washington 

 navel orange. 



As a result of observations and experiments, here noted, it was found that an 

 abnormal water relation obtains periodically in citrus foliage and in the young 

 fruits during the hot growing season in the dry interior valleys of California 

 and Arizona. A diurnal decrease in water content of the fruits occurs during 

 the afternoon and is accompanied by a considerable increase in the water 

 deficit of the leaves. " Negative pressures of considerable magnitude are found 

 in the water columns of citrus trees under the.se climatic conditions. These 

 attain their maximum during the afternoon. The dropping of the fruits appears 

 to be most severe where the above-mentioned water relations are most ab- 

 normal. Inasmuch as in the case of certain other plants the ab.scisslon of 

 young fruits lias been shown to be due to abnormal water relations it is 

 suggested that such may be the case here." 



Optimum moisture conditions for young lemon trees on a loam soil, L. W. 

 Fowler and C. B. Lipman {Univ. Cat. Pubs. Agr. Sci., 3 {1917), No. 2. pp. 25- 

 S6, pis. S, fig. 1). — In the experiment here described, which was conducted at 

 the Limoneira Ranch, Santa Paula, Cal., studies were made of tlie optimum 

 moisture content of a rather heavy loam soil for young Lisbon lemon trees 

 grown in cylinders. The data obtained in the course of the first two years of 

 the work are summarized as follows : 



"A moisture percentage of 20 based on the dry weight of the soil has pro- 

 duced the tallest trees. Trees grown with 16 and 18 per cent of moLsture, while 

 not as tall .ns those grown with 20 per cent of soil moisture, show better color 

 and more vigor. The differences are not very marked, however. 



"The foregoing facts seem to show that the ninge of optimum or nearly 

 optimum moisture percentages for the soil and plant in question is a relatively 

 wide one. Much more visible damage results to the young lemon trees from 

 moisture percentages in excess of the optimum than from those below the 

 optimum. Every successive increment of moisture beyond the optimum is 

 accompanied by a sharp depression in growth, color, and general vigor of the 

 trees. Every successive decrement of moisture from the optimum shows only 

 a relatively slight depression in growth. 



"The theoretical wilting point and the moisture equivalent for the siil studied 

 are in close accord, respectively, with the actual wilting point as determiiici] in 

 the soil of the orchard and the optimum moisture content as determined In the 

 experiment discussed above." 



