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descriptions o£ bitter pit and cork spot on apples, magnesium (Mg) 

 deficiency symptoms on pear leaves, manganese (Mn) deficiency and 

 toxicity symptoms on apple leaves and wood, and boron (B) toxicity 

 symptoms on apple leaves. For your information we have included 

 below photographs and brief descriptions of Mg and potassium (K) 

 deficiency symptoms on apple leaves and symptoms of B deficiency 

 on the fruit of Bosc pears. 



Mg Deficiency of Apple 



*■ Pictured on the left is Mg de- 



ficiency symptoms on apple leaves. 

 Deficiency symptoms are characterized 

 necrotic (brown) areas between the 

 veins. The older, basal leaves on 

 shoots and spurs are usually affected 

 first, and as the season progresses 

 the injury symptoms appear on the 

 younger leaves. The deficiency symp- 

 toms frequently become apparent in 

 late July and early August. By late 

 summer, the shoots on which leaves 

 show Mg deficiency may be defoliated 

 except for a few leaves near their 

 terminals. Mg deficiency increases 

 fruit drop at harvest. 



We consider the optimum levels 

 of Mg in leaves to be 0.25 to 0.401. 

 Symptoms of Mg deficiency are infre- 

 quent in comparison with 15 to 20 years 

 ago. Nevertheless, our leaf analysis 

 show that levels are frequently belov/ 

 0.30%. Thereby, the use of high magnesium lime which has been advo- 

 cated for years, continues to be needed in our orchards. 



K Deficiency of Apple 



Figure 2 shows leaf 

 margin burn caused by K 

 deficiency. This symptom 

 can be easily confused 

 with the leaf margin burn 

 from calcium chloride 

 sprays. However, unlike 

 leaf burn from calcium 

 chloride sprays, the scorch 

 of leaf margins due to 

 K deficiency progresses 

 from the older leaves to 

 the younger leaves of cur- 

 rent season shoots as the 

 season advances. The scorch 

 may turn gray in color and 

 leaf fall may occur late in 

 the growing season. Never- 

 theless, in 2 instances 

 leaf analysis was necessary 



