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  • Author or Editor: C. H. Klaren x
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Abstract

In ‘Delicious’ apple (Malus domestica Borkh.) trees affected by dead spur disorder (DS) no over-all deficiency was in N, P, K, Ca, amino acids, proteins, sugars or phenols as compared with healthy (CK) trees. N, amino acid and protein contents were higher in DS than in CK spurs on 1- and 2-yearold limb sections. Relatively low nutrient levels in DS spurs on 3-4-year old limb sections indicated that translocation of nutrients to these spurs was restricted. Phenol contents were lower in DS than in CK spurs. P and K contents were higher in DS than in CK spur leaves.

Open Access

Abstract

Pink phloem was found during the winter months in all spurs on ‘Delicious’ apple (Malus domestica Borkh.) trees affected by dead spur disorder and was less frequent the remainder of the year. On healthy trees pink phloem was found in young spurs, but seldom at the base of older spurs. The pigment was identified as the anthocyanin cyanidin-3-galactoside.

Open Access

Abstract

Spur wood and spur bark of ‘Delicious’ apple (Malus domestica Borkh.) trees affected by dead spur disorder (DS) grew more vigorously than those of healthy (CK) trees the first 2 years. Buds were smaller on DS than on CK trees. Leaves were smaller on DS than on CK trees on 2-year-old and older limb sections. DS trees produced most fruit on 2-year-old limb sections, whereas CK trees produced most fruit on 3-year-old limb sections. Length and diameter growth of the limbs was unaffected, but the internode length was shorter on DS than on CK trees. Death of the spurs was preceded by bud failure in the spring.

Open Access

Abstract

“Dead spur” is a disorder which affects the spurs of ‘Delicious’ apple (Malus domestica Borkh.). The spurs die on 2-year-old and older sections of the tree. A survey of ‘Delicious’ sports showed Royal Red, Earlistripe and Sharp have a higher incidence of dead spur than the other sports. There was no relationship of the disorder to rootstock, but the interstock Ottawa 292 increased the severity of dead spur.

Open Access