EXPERIMENT STATION BULLETINS. 175 



EXPERIMENT IN PRUNING. 



The question of when and how much to prune frost injured trees was one frequently 

 asked by fruit growers after tlie freeze. In order to study the effect of pruning at 

 different times and to varying degrees, and to gain, if possible, some new light on the 

 subject, an experiment was undertaken. Eight rows of twelve trees each were chosen 

 for the test in a block of ten-year-old trees. These rows included forty-eight varieties, 

 most of which were considerably injured. The pruning was done at intervals of ten 

 days, between April 1 and May 1, two rows being pruned at a time. The manner of 

 pruning was the same in the case of each lot of trees pruned. The first two trees in 

 each row were cut back on wood from one and one-half to two inches in diameter ; 

 the next two were pruned a little less severely, and so on, gradually lessening the 

 amount of wood removed until the last four trees in the row were reached. These 

 four were pruned in the ordinary way by thinning out and heading in a part of the 

 growth of the year before. On May 1, when the last pruning was done, trees on 

 which the fruit buds had not been entirely destroyed were in blossom and the leaf 

 buds were beginning to open. 



As the growing season advanced no variation could be discerned that could be 

 ascribed to difference in time of pruning. But there was an appreciable contrnst be- 

 tween trees pruned to different degrees. Among those cut back on wood from one 

 to two inches in diameter, twenty-one, or about one-third of .the whole number thus 

 severely pruned, either failed to start or sent out but a few weak shoots, which soon 

 withered and died. Of the trees pruned in the ordinary way none were lost, although a 

 few died back to a slight extent. They started a little earlier in the spring than did 

 the trees severely ])runed, and during the season made verv fair growth. Most of the 

 severely pruned trees which survived, although belated in starting, sent out strong and 

 vigorous new shoots. On a part of these trees the new growth was well distributed 

 and symmetrical new tops were formed, while in the case of others only a few scat- 

 tered shoots sprang from stumps of the large branches left in pruning. Trees headed 

 in on wood from about half or three-quarters of an inch in diameter, as were a part of 

 those included in the experiment, and nearly all others on the grounds, with but few 

 exceptions, survived and made a good development of new wood. 



To summarize briefly, difference in time of pruning made no appreciable difference 

 in results. Very severe pruning or removing all the tops down to the stumps of main 

 branches proved dangerous to the life of the trees. More moderate pruning or cutting 

 back on branches from one-half to three-fourths of an inch in diameter gave good 

 results. Trees pruned in the ordinary way were not, at the close of the season, in 

 quite so good condition as those pruned more severely. These rpsults are not consid- 

 ered conclusive. Further differences in the behavior of trees differently treated may 

 yet be detected, as the observations have extended only over one season. 



EXPERIMENTS IN SPRAYING. 



For the purpose of further testing the best methods of combatting leaf curl, which is 

 one of the most serious fungus diseases of the peach in Michigan, experiments with 

 Bordeaux mixture and copper sulphate solution were undertaken. About the m'ddle 

 of March, part of the trees included in the experiment were sprayed with copper 

 sulphate, one pound to twenty gallons of water. On April 2t). at which time the 

 buds were beginning to show some color, but before any had actually opened, other 

 trees, nearly all of the same varieties as those sprayed in March, were given an appli- 

 cation of the same solution used at the same strength. At the same time some of 

 the trees first sprayed were criven a second application. After the fruit had set, a row 

 of trees sprayed early and another sprayed late were atrain spraved. For this appli- 

 cation, Bordeaux mixture, consisting of four pounds copper sulphate, four pounds of 

 lime and forty gallons of water, was used. 



The season proving unfavorable for leaf curl, but few varieties were badiv affected, 

 no matter what the treatment had been. However, the disease appeared sufficiently to 

 show a marked difference between early and late sprayed trees. Trees spraved in April 

 just before the opening of the buds showed a much larger per cent of curled leaves than 

 those sprayed in March. The second application of copper sulphate to early sprayed 

 trees made no appreciable difference in the amount of curl, and the same was true of 

 Bordeaux mixture applied after the fruit had set. These results accord very nearly 

 with those obtained by somewhat similar experiments carried on here each snring 

 for a number of years past. In a ceneral way it may be said that thoroucrh spraying 

 with copper snlphafe solution in March, while the buds are dormant, is, under most con- 

 ditions, an effectual remedy for curl leaf. 



