- 8 



and subsequent winter injury. The winter injury problem has 

 restricted exclusively to light sandy soils where the cold in- 

 protection given by water is at a minimum. Trees grown in 

 loam and cultured on a grass or a controlled grass sod gener- 

 show no signs of injury. In Washington State, some rootstock 

 tree vigor influences on winter injury were noted. Red Deli- 



trol 

 been 

 jury 

 clay 

 ally 

 and 



cious trees on seedling roots were completely killed by low temper- 

 ature injury, while trees on EM VII were unaffected. Excessive in- 

 jury to low vigor Red Delicious trees on seedling roots was reported 

 whereas more vigorous trees were not injured. 



Stu Carpenter, Extension Specialist from Southwest Michigan, 

 suggested that the winter injury problem on sandy soils may be con- 

 trol 1 ed by : 



1. Partial weed 

 with such as 



control through 

 Paraquat . 



the use of contact herbicides 



2. A program of herbicides plus mulch. 



3. Make the band sprayed in the tree row smaller. 



It may be added that in Massachusetts one spray application 

 made in early May generally allows sufficient regrowth of grass and 

 weeds by late fall to eliminate the possibility of winter injury to 

 the roots . 



*************** 



RESEARCH FROM OTHER AREAS 



Department 



Wn 1 iam J . Lord 

 of Plant and Soil 



Sci ences 



Concentrate Sprays for Thinning Apples : Our circular on chemical 

 thinning of apples suggests that thinning materials be applied alone 

 and in dilute form (IX). We suspect, however, that some growers 

 concentrate their thinning sprays to some extent--2X to 4X--and 

 furthermore, interest in concentrate spraying has increased drasti- 

 cally during the last 2 years. Therefore, the question arises about 

 the feasibility of concentrating thinning sprays. 



The principal reason why we have been hesitant to suggest con- 

 centrating thinning sprays is the increased potential for error due 

 to errors in mixing of sprays and in calibration of spray equipment. 

 Doublingthe concentration, doubles the size of any error in thin- 

 ning, the margin for error is often small. Nevertheless, there are 

 examples of successful application of hormone sprays in concentrated 

 applications. We know, for example, that preharvest drop-control 

 materials are concentrated when applied by airplane, and results 



