42 Experiment Station Bulletin 345 



increased 800 to 900 per cent in height over that observed at the begin- 

 ning of the experiment, while those making the poorest growth increased 

 only 25 to 50 per cent. On the poor trees the leaves were also small. 

 Zinc was used in the tests in an attempt to determine the cause of small- 

 sized leaves as it is known that in some soils many plants develop small 

 leaves because of a zinc deficiency. Trees grown in soil taken under the 

 healthy tree grew rapidly and generally made as good growth as the 

 best trees in the treated soils described above. That the two soils differed 

 from each other was otherwise evidenced by the difference in certain 

 characteristics of the trees. The soil beneath the scorched tree was 

 lighter in color and texture and apparently of poorer water-holding ca- 

 pacity than the soil beneath the healthy tree. 



When samples were taken in the orchard it was noted that the 

 "feeding" roots of the badly scorched tree mingled with the grass roots 

 just beneath the soil surface and were not found below this level. The 

 "feeding" roots of the healthy tree penetrated the soil more deeply. This 

 test is being repeated. 



In the fall of 1941 data were collected for the construction of cor- 

 relation tables in relation to visible tree characteristics in both the Good- 

 win and Hewitt orchards. From this data partial correlations were cal- 

 culated and compared favorably with values obtained in 1940. There was 

 a highly significant positive correlation between scorch and defoliation 

 and between the amount of scorch on the tree and the degree to which 

 the leaves were affected. 



Observations have been continued on apple trees receiving borax in 

 the orchard. Only trees sprayed with a saturated solution showed any 

 injury to the leaves. Where borax was applied to the soil, trees receiving 

 less than 5 pounds of borax in 1940 are healthy. Heavier applications re- 

 sult in trees possessing smaller leaves of paler color due to apparent de- 

 ficient chlorophyll production between veins. Young fruit on trees 

 which received 10 and 20 pounds of borax was yellowish rather than 

 normal dark green. These trees showed no apparent ill effects following- 

 borax application in 1940. Interesting effects of borax on growth of 

 apple trees in the greenhouse are being checked concurrently. (L. P. 

 Latimer, G. P. Percival) 



Use of Mailing and Other Dwarf Apple Rootstocks 



Observations on the production, size, and stability of trees of the 

 several varieties on various rootstocks were made. Results to date show 

 that the trees on Mailing No. 3 and Mailing No. 4 planted in 1938 have 

 been very productive, especially with the variety Golden Delicious. 

 There is some indication that some of these varieties even on No. 4 have 

 been so precocious as to dwarf the trees unreasonably, rendering them 

 too small for commercial planting. However, in general, trees on No. 4 

 seem to be behaving nicely in obtaining size and productivity for a com- 

 mercial orchard. Observations in the grafted orchards where varieties of 

 .Mcintosh, Spy, and Cortland have been worked onto the body stock 

 of Virginia Crab and Florence Crab indicate that the growth has been 

 much better on the Florence Crab than on the Virginia Crab. There is 



