- 8 



Our tolerance study indicated that Lorsban* (chlorpyrifos) would be a 

 viable substitute and our field trials in 1984 support these results. A 

 single petal fall application on the same acreage as previously discussed 

 provided excellent control of GFW larvae resulting in less than 0.4% injury 

 to ■''ruit at harvest. Thiodan* (endosulfan) also proved to be an effective 

 material in a similar trial and due to its relatively mild effect on benefi- 

 cial mite predators, it would be well suited to an integrated mite control 

 program. 



Pesticide resistance and subsequent control failures are common pheno- 

 mena. Occurrences such as the one described here continue to remind us of 

 the need for pest monitoring programs and the selective use of pesticides in 

 order to lengthen the effective "lifetime" of current spray materials. 



***** 



SOME COMMENTS ON APPLE TREE NUTRITION 



William J. Lord 

 Department of Plant and Soil Sciences 



James T. Williams, Massachusetts Regional Fruit Specialist, reports the 

 '"oHowing summary of apple leaf analyses for Northeastern Massachusetts 

 jrchards in 1982 and 1«83. 



Pet. of samples Pet. of samples 



Element below optimum range above optimum range 



Nitrogen 8 15 



Potassium 31 6 



Calcium 50 



Magnesium 5 1 



Boron 17 



Manganese 10 10 



Copper 36 3 



Zinc 5 40 



A grower should obtain leaf analyses to assess the status of his own 

 orchard, hut the table above shows that calcium, copper, potassium, and 

 boron were most frequently deficient in leaves, and that zinc and nitrogen 

 were the elements most commonly in excess. 



Some general comments about apple nutrition follow. 



Apple tree nutrition . The needs of apple trees for mineral elements are 

 smaller than those of many other crops. Nevertheless, the problems of main- 

 taining optimum nutrition are complex because of the concern with nutrition 

 of both the tree and the fruit, and because of the influence of soil manage- 

 ment and orchard intensification on mineral availability. 



