HORTICULTURE. 743 



Orchard irrigation studies in the Rogue River Valley, C. I. Lewis, E. J. 

 Keaus, and R. W. Rees (Oregon Sta. Bui. 113, pp. .'/7, figs. 11). — During the 

 past 5 years the station has been conducting orchard irrigation investigations, 

 especial attention being paid to a determination of the best dates as well ms 

 the best amounts and ways of applying the water under the various soil and 

 orchard conditions found in the Rogue River Valley. The work for each season 

 is here discussed in detail. 



Irrigation practices in the Rogue River Valley were found to vaiy according 

 to the soil, the kind of fruit grown, and the age of the trees. Some of the 

 heavier soil types have shown best results under cultivation without the use of 

 water. Soils of mediimi texture derived a direct benefit from light irrigation. 

 The lighter types of soil under ordinary circumstances show that a considerable 

 amount of irrigation is necessary for the production of commercial fruit on 

 heavily bearing trees. The use of an excessive amount of cold water in the 

 iirigation of pear trees on sticky soils is considered a questionable practice, 

 since it did not increase the size or quality of the fruit and the result on the 

 tiee was detrimental rather than beneficial. Bartlett pear trees which are in 

 good vigor and planted on strong soils appear to become more susceptible to 

 disease under irrigation. 



Irrigation aided in giving a larger percentage of fruit of marketable size. 

 In some cases the reduction in the number of windfalls amounted to as high 

 as 15 per cent of the crop. There were less culls caused by calyx cracking on 

 the 'irrigated plats than on the dry checks. Irrigation had a tendency to keej) 

 both the wood and foliage more active in the fall, as well as to prevent prema- 

 ture ripening of the fruit. The shape of the fruit was found to be materially 

 changed by irrigation. The apples receiving the best care were more elon- 

 gated and angular, while those that suffered through lack of moistui'e Md a 

 tendency to become flat. The effect on color was more noticeable on the 

 lighter soils where red apples were grown. The irrigated apples had a brighter, 

 more attractive color while those grown on the checks were duller yet deeper 

 in color. In many cases irrigated trees had more numerous and stronger fruit 

 buds for the succeeding crop. By means of irrigation a much better stand of 

 cover crop can be secured in late summer and early fall. Attention is called 

 to the importance of cultivation and good drainage as adjuncts to irrigation. 



The temperature of well water was found to increase in some cases as much 

 as 8A° during the day while flowing in open furrows to the point of distri- 

 bution. Water used fi'om an irrigation ditch showed in some cases an increase 

 of 15^° over the morning temperature. In both cases where temperatures were 

 read it was found that the soil had deci'eased in teaiperature immediately fol- 

 lowing the irrigation. The decrease was more noticeable in the surface soil. 

 It amounted in some instances to a difference of 3° in temperature. 



To assist in determining the benefit or detriment of irrigation with respect 

 to the development of the fruit itself, a study of the effect of irrigation on the 

 chemical composition of the apple is now in progress. 



Cover crops for Michigan orchards and vineyards, H. J. Eustace {Michi- 

 gan Sta. Circ. 18, pp. 123-134, figs. 10). — This circular describes the most com- 

 mon systems of orchard soil management, and discusses the value of various 

 plants for cover ci'op purposes as determined in orchards of various ages and 

 o)i different soil types and located in various parts of the State. 



Of the leguminous crops winter vetch and Mammoth clover appeared to be 

 the most valuable, the latter doing somewhat better than winter vetch upon a 

 clay soil. Spring vetch and Canada peas have also proven of value. Of the 

 nonleguminous crops buckwheat, rye, oats, and barley were found to be adapted 



