April 14, 1922] 



SCIENCE 



387 



out of the question a few years ago is gi-eatly 

 facilitated now by the increasing number of 

 abstract journals and substantial help is af- 

 forded investigators in many institutions by 

 Plant Science Seminars, Scientific Societies 

 and the like. Even though such conveniences 

 )je lacking much can be gained by personal con- 

 tact with investigators in other fields and by a 

 mutual exchange of criticisms and suggestions. 



Treatment — that is, orchard practice, 

 whether it be pruning, irrigation, fertilizing, 

 thinning or what not — -is an aspect of horticul- 

 ture that may be compared to medicine, and 

 the comparison is instructive because it indi- 

 cates a possibility of development in horticul- 

 ture from the application of scientific methods 

 iitsed by the physician or surgeon. Cultivation, 

 pruning, tlie use of fertilizers and other treat- 

 ments have been considered only in the light 

 of one standard, the effect on crop production. 

 The limitations of this one-tracked system may 

 be demonstrated by reference to some recent 

 experiments on fertilizer treatments. 



If apple trees are bearing poor crops, a 

 spring application of some quickly available 

 nitrogenous fertilizer will frequently increase 

 the yield. Such increases are very striking on 

 weak trees, but some results obtained at Mis- 

 souri show they can be obtained also on trees 

 in good condition — on trees that are already 

 bearing fair or even good crops. This effect 

 of quickly available nitrogenous fertilizers ap- 

 plied a couple of weeks before blossoming has 

 been shown to be produ.ced by increasing the 

 set of fruit. Fruit setting, however, is only 

 one step in fruit formation. The process be- 

 gins with the formation of fruiting wood and 

 involves in succession fruit bud differentiation, 

 bud development to the time of blossoming, 

 pollination, fruit setting and finally fruit de- 

 velopment. The failure or limitation of a crop 

 may be occasioned by interference with any one 

 of these successive processes. It would make 

 little difilerenee how favorable conditions might 

 be for fruit setting, if fruit bud differentiation 

 had not occurred. Recent investigations have 

 shown that those conditions in apple trees, pro- 

 duced by spring applications of quickly avail- 

 able nitrogenous fertilizers, which are so favor- 



able to fruit setting, do not favor fruit bud 

 diii'erentiation. Hence if poor crops result 

 from deficiency in the initiation of fruit buds, 

 spring applications of quickly available nitro- 

 gen would only accentuate the trouble. 



This work reopens for investigation the entire 

 orchard fertilizer problem which was thought 

 by many to have been solved in the last few 

 years by experimental work with sodium ni- 

 trate in the orchard. The same kind of fruit 

 tree may present many different nutritional 

 problems for treatment. Each problem re- 

 quires special study and the remedy in horti- 

 culture, as in medicine, depends on accurate 

 diagnosis. The use of fertilizers to correct the 

 alternate bearing habit in apple trees consti- 

 tutes a problem as distinct from their use in 

 increasing the set of fruit as spraying peaches 

 for San Jose scale is from spraying to control 

 scab. As investigators, we are too ready to dis- 

 pose of problems by assuming that either the 

 nutrition, the moisture or the temperature re- 

 lations are involved and that cultivation or the 

 application of some fertilizer will lead t-o 

 maximum growth and productivity. We would 

 spare ourselves the effort of analyzing the 

 problem — of making a diagnosis to detennine 

 the precise dilflculty to be overcome. The time 

 is not far distant when fertilizer treatments 

 alone will be as numerous and as specific as all 

 the horticultural practices recognized today. 

 AVe must dispense with the idea of a mass at- 

 tack on a bulk problem and apply more de- 

 tailed methods, if we are to make rapid prog- 

 ress. Aside from technical improvements in 

 such fields as spraying- and marketing, the lines 

 of pomological investigation along which gi'eat- 

 est progress seems possible are treatment, pro- 

 pagation and plant improvement and treatment 

 according to diagnosis promises to be one of 

 the most fruitful. 



There is no cure-all, no patent remedy for 

 promoting growth, for inducing hardiness or 

 for increasing crops. These can be accom- 

 plished only by careful study and hard work. 

 No practice can be recommended for all cir- 

 cumstances or for all fruit plants, nor can the 

 same practice be guaranteed to produce the 

 same effects under different conditions. Treat- 



