they ripen, fruit lose their ability to fight-off invading 

 pathogens. Bruising, then, must in some way help the 

 fungus enter the fruit, and then advancing ripeness allows 

 that fungus to more easily rot the apples. Figure 1 shows 

 dramatically how the consequences of bruising worsen as 

 the bruising occurs on progressively riper fruit. 



In earlier articles [Fruit Notes 53(4):15-17 and this 

 issue pp. 6-7], results of packing-line studies of bruising 

 were reported. In the study reported here, the authors 

 projected the amount of rot that likely would result from 

 the bruising incurred by Golden Delicious apples passing 

 through commercial packing lines. 



They conclude that bruising of ripe apples on a con- 

 taminated packing line (and they all are contaminated) 

 would directly lead to 4 to 8% of the tray-packed apples 

 rotting within 5 days at 75°F, and that less ripe apples and 



cultivars other than Golden Delicious probably would not 

 rot as badly. However, the projections of the authors show 

 what can happen and may help explain why some lots of 

 apples are rejected because of excessive rotting. Clearly, 

 bruising during the grading and packing operations can 

 lead to substantial rotting as well as to the direct quality 

 loss caused by appearance of the bruises themselves. 



In their earlier studies [Fruit Notes 53(4):15-17 and 

 this issue pp. 6-7], the authors showed that much of this 

 bruising is preventable, and they described what packing- 

 line operators should be looking for, and gave some 

 suggestions for alleviating the problem. 



The results described here also re-emphasize the 

 importance of practices to reduce build-up of fungal 

 spores on and around fruit. A recent article [Fruit Notes 

 53(3):15-16] examined this problem and offered sugges- 

 tions for controlling apple rotting. 



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Blueberry Nutrition 



Dominic A. Marini 



University of Massachusetts Cooperative Extension, Hanson, MA 



For high yields, blueberry bushes must be vigorous, 

 making at least 12 to 18 inches of new growth per year. The 

 most productive shoots are those with 15 to 20 leaves. Low 

 vigor can be the result of improper or no pruning, dry or 

 wet soil conditions, incorrect soil pH, or lack of nutrients. 



Pruning must be done annually in late winter or early 

 spring. Mulching with sawdust or wood chips is ideal for 

 conserving soil moisture and preventing drought stress. 

 Many growers, particularly on light, sandy soils, are using 

 trickle irrigation to supply moisture during drought peri- 

 ods. Wet soil conditions can be corrected by soil drainage 



m some cases. 



Soil Acidity 



Blueberries require an acid soil, the ideal pH being 

 between 4.5 and 5.5. If the pH is below 4.5, dolomitic or 

 high magnesium limestone should be applied to raise the 

 pH, while sulfur may be used to lower the pH. In addition, 

 fertilizers having an acid reaction should be used, such as 

 most complete fertilizers (10-10-10, etc.), ammonium 

 sulphate, and ammonium nitrate. Do not use fertilizers 

 having an alkaline reaction, such as sodium nitrate, cal- 

 cium nitrate, cyanamide, bone meal, and wood ashes, 

 unless the pH is 4.6 or lower. 



Nutrients 



It is generally agreed that nitrogen is the most impor- 

 tant of the major elements required by blueberries, the 



ammonium form being preferred to the nitrate form. 

 Little or no response has been observed to phosphorus or 

 potassium applications although one Massachusetts 

 grower reports improved growth and production from 

 application of superphosphate. In the field, the only 

 deficiency symptoms observed are those of nitrogen, iron, 

 and magnesium. Symptoms of nitrogen deficiency include 

 stunted growth, yellowing, and, under severe deficiency, 

 reddening of older leaves. Iron deficiency appears on the 

 new growth with the leaves becoming bright yellow, while 

 magnesium deficiency usually becomes apparent at har- 

 vest as yellowing between the veins and of leaf margins of 

 older leaves while veins remain green. Both iron and 

 magnesium deficiencies are usually corrected by adjusting 

 pH to the optimum range. Environmental factors that can 

 be confused with nutrient deficiency symptoms include 

 drought stress, poor drainage, cool weather during the 

 growing season, insect or disease injury, fertilizer burn, 

 and injury from pesticides and herbicides. Therefore, a 

 soil test or leaf tissue analysis is advisable if a nutrient 

 deficiency is suspected. Soil samples should be taken in the 

 fall while leaf samples should be taken from July 15 to 

 August 15. 



Fertilizer is usually applied in a ring around the bush 

 or in broad bands on both sides of the row. On newly-set, 

 young bushes a 6-inch ring around the bush 12 inches from 

 the crown is recommended when new growth starts. A 

 second application may be made in late June or early July 

 and a third in late November before the ground freezes. 



On newly set plants the recommended amount of 



