98 MASS. EXPERIMENT STATION BULLETIN 378 



peat. The paired trees were set between the trees in a newly planted or- 

 chard in four locations representing different degrees of soil depth, fertility, 

 and moisture. Pruning was intentionally severe. All trees were cut back 

 to 2-3 feet and the laterals removed. 



Neither during the summer of 1939 nor during the summer of 1940 

 could any consistent differences in growth be detected in the field. Meas- 

 ured by trunk diameter, the check trees apparently have grown as well 

 as the trees planted with peat moss. On three out of the four locations 

 the treated trees grew slightly more but the differences are not signif- 

 icant. 



Other work, notably at the New York Agricultural Experiment Station, 

 has shown good results from the use of peat moss at planting time. Peat 

 favored root growth and spur development. Since it is possible that trunk 

 diameter may not accurately reflect total growth, it is planned to make 

 further studies for any possible effects from the peat treatment. Then, 

 too, there is the possibility that peat used in propagation frames for a 

 season may not be as effective as "fresh" peat. There is no doubt that 

 peat favors rooting under many circumstances, perhaps through improved 

 aeration of the soil. Other investigation has shown that the best results 

 are obtained in seasons with excessive soil moisture in the spring followed 

 by drought conditions in midsummer. 



It is suggested that as far as planting in Massachusetts is concerned, 

 the natural soil and the site are the important factors. A poor orchard 

 soil is extremely difficult to improve sufficiently for maximum tree per- 

 formance. The use of peat in the planting operation does not seem neces- 

 sary on a good soil, though it may prove helpful in some instances. 



Soil Acidity in the Orchard. Repeated applications of sulfur sprays 

 and dusts may cause an increase of soil acidity injurious to grass or cover 

 crop and possibly to the trees. Samples of the top three inches of soil . 

 were taken from beneath a Mcintosh tree growing in sod, which had been 

 sprayed following the current schedules for over 20 years. Lime-sulfur 

 was most used but wettable sulfurs and sulfur dusts have been increasingly 

 used. Results were as follows: 



Distance from pH Value 

 trunk, feet 



4 4.50 



9 4.80 



15 (under branch tips) 5.08 



20 (midway between trees) 5.60 



The steady decrease of pH values, and therefore increase of acidity, 

 towards the trunk is interesting. Probably sulfur sprays tend to run 

 down and drip from the main branches; also when the trees were small, 

 only the more central part of the area was subject to spray drip. The 

 soil near the trunk is ten times as acid as that outside the branch tips 

 and is too acid for many crops. While apple trees are quite tolerant of 

 acid conditions, they may suffer at least indirectly from acid conditions 

 such as these. 



Another case of possible soil toxicity in a Sudbury orcliartl was called 

 to our attention. A visit to the orchard showed that many trees were 

 not vigorous and the grass and weeds under such trees were dead. The 

 line of demarkation under the tips of the branches was sharp. The trees 



