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  • Author or Editor: Timothy E. Crocker x
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In 4 experiments conducted to study internal bark necrosis (IBN) in apple, ‘Delicious’ trees were treated with Mn, Fe, Cu, and Al (100 and 200 ppm in nutrient solution), Mn, Fe, Cu, plus Al (50 ppm each) and a minus B treatment. Only trees receiving Mn and minus B developed IBN symptoms. Trees grown under normal and low levels of Ca and receiving variable concentrations of Mn (0, 25, 50, 75, and 100 ppm) developed IBN in proportion to Mn concentration. Spur-type and standard ‘Delicious’ trees did not differ in IBN severity. Bark samples with IBN symptoms, when analyzed on the electron microprobe x-ray analyzer, had greater Mn and Ca concentrations in necrotic tissue areas than in non-necrotic areas. IBN lesions induced with minus B had a higher Ca concentration in necrotic areas than in healthy tissue

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