308 



PRINCIPLES AND PRACTICE OF PRUNING 



pinching is empliiyed to leave at least 4 leaves beyond the last 

 bunch of grapes." 



Later experiments in grape-shoot pinching by Riviere show 

 that the sugar content increased from 159 gm. per litre of must 

 where no leaves were left beyond the bunches to 205 gm. where 

 5 leaves were left. No further increase was obtained where G or 7 

 leaves were left. Similar results were found for the acid content, 

 which decreased from an amount corresponding to 3.95 gm. sul- 

 phuric acid per litre where no leaves were left to 3.65 gm. where 

 5 leaves were left. As a result of the work it is recommended that 

 in pinching back the bearing shoots 5 leaves should be left beyond 

 the second bunch. 



219. Wounds, their effects and treatment. — Barring frosts, drouths, 

 diseases, insects and accidents, properly mana.ged vineyards may 

 continue productive perhaps indelinitely. The most frequent yjroxi- 





FIG. 267— RECURVING THE CANES AS IN THE FAN SYSTEM USUALLY TENDS 

 TO PROMOTE FRUITFULNESS 

 In this system the trunk may be trained as a permanent single stem which 

 reaches to the first wire; or in ret^ions where laying down is necessary the renewal 

 canes may be started from a short stalk near the gronnd. Some fruit will be pro- 

 duced on the short arms during the third season. However, with the average young 

 \ine the v\'ood should be headed back pretty severely so as not to permit o\'er-hearing. 



mate cause of decline is the cumulative effect of little injuries, sucli 

 as pruning wounds, which permit the entrance of disease, decay and 

 insects as well as interfere with the physiological functions of the 

 plant. Hence the smaller the wounds the better, especially on the 

 main trunk and the arms. By proper planning, large wounds niiiy 

 liC avoided more or less completely. yVntiseptics and wound dress- 

 ings may be used as in the treatment of tree fruit wounds (Chap- 

 ter VlIT). 



L. Petri*, an Italian investigator, found that two fungi were al- 

 ways present in the brown streaks which follow pruning of grape- 

 vines; mainly, Ccphalosporium and acremoniuin. He believes the 



• Staz. Sper. Agr. Ital. 45, No. 7, Page 501. 



