Page 14 



BETTER FRUIT 



J an liar \ 



TABLK II.— SHOWINT. PROBABLE RESULTS 

 I-ROM DIII-ERENT METHODS OF PRUN- 

 ING ONE HUNDRED SHOOTS, EACH 

 HAVING TEN EQUALLY SPACED 

 LATE1\AL BUDS. 



Light Heavy Light Heavy 

 (30%) (60%) (30%) 160%) 

 heading heading thinning thinning 

 baclv out out 



Number lei-niinal 



buds left 



Number lateral 



buds left 



Nuudjer new 



shoots formed. 

 Number new 



spurs formed . . 

 Number buds re- 



main'g dormant 



Figure 48 — An old Bartlett pear tree that several years ago was in the con- 

 dition of (hat shown in Figure 47. An atlemnt was made to reinvigorate its 

 old weak spuis bv "dehorning," a very heavy heading back of the top part 

 of the tree. The I'esull has been the formation of a large number of strong, 

 vigorous shoots that in turn have developed many vigorous fruit spurs. 

 Howevei-, the old spurs in the lower part of the tree have remained much as 

 they were. They have not been invigorated to any marked extent. Thinning 

 out' instead of "heavy heading back would probably have alTorded very 

 (Hlftrent results. 



common oljservation thiit the m;un 

 .shoot growth of the .season, in trees 

 with non-lieailed shoots, develops from 

 these teiniinal Ijiids. In I'act compara- 

 tively few of the lateral buds develop 

 into shoots, most of them starting but 

 only growing out into spurs. Were we 

 to assume that from seven hundred 

 and seventy buds, seven hundred lat- 

 eral and seventy terminal, on the 

 seventy shoots remaining after a light 

 thinning, we obtain one hundred and 

 forty shoots and four hundred and 

 ninety spurs, leaving one hundred antl 

 forty dormant buds, we would prob- 

 ably not come fa'- from what would be 

 actually obtained. 



.\ heavy thinning out of this same 

 theoretical tree we arc considerine, a 

 thinning out that would remove sixty 

 per cent of the shoot growth of the sea- 

 son, would leave forty untouched 

 shoots. Each of these would have a 

 terminal bud and ten etiually-spaccd 

 lateral buds, and would probably be- 

 have the following season in much the 

 same manner as the unijiuncd shoots 



of the lightly-thinned tree. Were this 

 the case the result would be eighty 

 new shoots (forty froiu the terminal 

 buds and forty from as many lateral 

 buds), about three hundred and twenty 

 snu's and forty dormant buds. The in- 

 dividual shoots might be longer and 

 strongei', and the individual spurs 

 thicker and more vigorous in appear- 

 ance, but probably the proportion of 

 buds to develop into fruit-spurs would 

 remain about the same. 



When the results to be expected from 

 a light thinning out are compared with 

 those to he expected from a heavy thin- 

 ning out, it is seen that the light thin- 

 ning alTords a larger number of both 

 spurs and shoots, though it is reason- 

 able to assmue that the .shoots will be 

 shorter and the spurs somewhat less 

 vi,ffor(nis than those of the heavily 

 thinned trees. 



That the probable efTects of these 

 diPferent pruning practices may ~Bc 

 more readily compared, they are pre- 

 sented in tabular form: 



bacli 

 



7(11) 



■3on 



200 







KID 



2.")0 



150 



.50 



out 

 70 

 7(10 

 1 10 

 400 

 1 10 



40 



too 



80 



.■!20 



40 



Heading Back vs. Thinning Out 



If the results from heading back are 

 compared with those from thinning 

 out, it becomes evident that both 

 processes tend to stiiuulate the forma- 

 tion of both new shoots and new fruit- 

 spurs. However, heading back affords 

 the greater stimulus to fruit-s])m- for- 

 mation. This is true whether it is light 

 heading back and light thinning out or 

 heavy heading back and heavy thin- 

 ning out that are being compared. 



What has just been said regarding 

 the influence of difTerent pruning prac- 

 tices upon the formation of new fruit- 

 spurs applies with almost equal force 

 to their influence upon the longevity 

 and regularity of bearing of already- 

 formed fruit-spurs. It might be rep- 

 soned that heading back in general. 

 and especially heavy heading back, be- 

 cause of its limiting the formation of 

 new fruit-spius, would tend to divert 

 food material into those already formed 

 and cause theiu to be more vigorous, 

 more long-lived, more regular in bear- 

 ing. On the other hand, heading back 

 seems to show a tendency to divert 

 food material into new shoots rather 

 than the old spurs. These new shoots 

 develop mainly in the outer and upper 

 parts of the tree, leaving the spurs in 

 the lower and inner portion in a weak- 

 ened condition. The result is that they 

 will probably bear less regularly and 

 die earlier than spurs which have an 

 abundant food supply. Furthermore, 

 very heavy beading back will even 

 force into shoot growth soiue of the 

 already-formed spurs. 



Thinning out, on the other hand, will 

 not only divert an extra amount of food 

 material into the older fruit-spurs on 

 account of its reduction of shoot 

 growth, but it also lets light into the 

 center of the trees, so that the leaves 

 of each spur arc better able to manu- 

 facture the food materials needed to 

 keep these spurs vigorous and thrifty. 

 This should enable them to live longer 

 and bear more regularly. Light thin- 

 ning out probably affords the larger 

 number of fruit-spurs, and heavy thin- 

 ning out the stronger, more vigorous 

 and long-lived ones. 



Continued in next issue 



SIMPSON,? 



RCO 



BANKBLDO. 

 PORTLAND. OREGON. 



