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  • Author or Editor: G.H. Neilsen x
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Abstract

‘Delicious’, ‘Golden Delicious’, ‘Spartan’, and ‘Mcintosh’ (Macspur) apple (Malus domestica Borkh.) orchards with low leaf Zn concentration, typical of many orchards in British Columbia, but with otherwise adequate nutrition were monitored for leaf Zn concentration throughout the 1983–85 growing season. Mid-terminal leaf Zn concentration consistently declined from a high of 40 µg·g–1 in early May to values approaching or below the 14 µg·g–1 deficiency concentration, despite annual sprays of dormant Zn.

Open Access

Traditionally, broadcast or foliar fertilizer applications sufficed to improve the nutrition of many irrigated, deciduous fruit orchards in western North America. Recent developments, including adoption of low-pressure, micro-irrigation systems and planting at higher densities (especially for apples), have increased interest in controlled application of fertilizers directly with irrigation waters (fertigation). The possibility of using fertigation to synchronize fertilizer application and plant nutrient uptake seems attractive as environmental concerns to minimize leaching of nutrients (especially N) to groundwater increase. Recent fertigation research in western North America will be reviewed and compared to traditional fertilizer application methods to assess the potential of fertigation to overcome inadequate nutrition. Emphasis will be placed on the use of soil solution monitoring to assess changes in soil NPK status. Tree response will be illustrated by studies in high-density orchards where N, P, K, Ca, B, or Zn have been fertigated.

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Zinc supplied as a fulvic-based Zn compound was absorbed and retranslocated to unsprayed new growth as effectively as zinc sulphate in apple seedlings of low Zn status grown hydroponically in the greenhouse. Similarly, fulvic- and humic-based compounds were as effective as zinc sulphate at improving short-term growth and Zn uptake into new tissues in Zn-deficient apple seedlings, with the best growth occurring at spray concentrations of Zn at 500 mg·L-1. Under field conditions, Zn concentration of peeled and washed `Jonagold' apples at harvest was increased, without phytotoxicity, by two or four postbloom sprays of fulvic Zn. It is therefore possible to use this material safely as an effective Zn-source after bloom. However the mobility of the foliar-applied Zn is limited and any yield response by treated apple orchards of marginal Zn nutrition is unlikely to occur in the short term (within two growing seasons).

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`Spartan' apple (Malus×domestica Borkh.) trees on M.9 (T337) rootstock were planted in April 1994 at 1.25 m × 3.5 m spacing. Seven soil management treatments were applied within a 2-m-wide strip centered on the tree row and arranged in a randomized complete-block experimental design. Treatments included a weed-free strip (check) maintained with four annual applications of glyphosate; surface application of 45 t·ha-1 of Greater Vancouver Regional District (GVRD) biosolids applied in 1994 and again in 1997; mulches of shredded office paper; alfalfa (Medicago sativa L.) hay; black woven polypropylene; and shredded paper applied over 45 t·ha-1 GVRD-and Kelowna-biosolids applied in 1994 and 1997. All experimental trees were fertigated with phosphorus (P) in the first year and with nitrogen (N) annually. Cumulative yield for the first five harvests was higher for trees subjected to any soil management treatment relative to check trees. Maximum cumulative yield, exceeding check trees by 80%, was measured for trees grown with a shredded paper mulch with or without biosolids application. Trees from the three shredded paper treatments were the only ones significantly larger than check trees after six growing seasons. No increases in leaf nutrient concentration were consistently as sociated with improved tree performance. Notable effects included increased leaf P concentration associated with biosolids application, increased leaf K concentration after alfalfa mulch application and temporary increases in leaf Zn and Cu concentration associated with application of biosolids high in Zn and Cu. Use of both mulches and biosolids amendments benefits growth of trees in high density plantings despite daily drip irrigation and annual fertigation.

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Authors: and

Abstract

Growth of Zn-deficient apple seedlings (Malus domestica Borkh. cv. McIntosh) grown in the greenhouse responded equally well to chelated or mineral Zn foliar sprays of the same Zn concentration. Absolute leaf Zn uptake, but not leaf Zn concentration, was a good measure of growth response. Foliar sprays with a concentration greater than 2.5 × 103 µg Zn/ml were required to correct Zn deficiency and adequately support growth of severely deficient seedlings for a month.

Open Access
Authors: and

Abstract

Field experiments of chelated-or Epsom salt-Mg sprays in 1981 and 1982 on ‘Delicious’ (Red King and Starking strains) and ‘McIntosh’ apple trees (Malus domestica Borkh.) indicated that a minimum of 2 x 2.8 kg Mg/ha, foliar-applied, was necessary to increase leaf-Mg concentration to desired 0.26% levels in ‘McIntosh’. Thus, label-recommended application rates for chelated Mg (2 x 0.56 kg Mg/ha) were too low. ‘McIntosh’ extension growth was increased by adequate foliar-Mg applications, although leaf Ca was reduced in 1 year by the foliar-Mg treatments.

Open Access
Authors: and

Abstract

Zinc-deficiency symptoms and relatively low mid-terminal leaf Zn concentrations were observed in apple seedlings (Malus domestica Borkh. ‘McIntosh’) grown in a minus-Zn Long Ashton solution comprised of reagent grade but unpurified chemicals. Leaf Zn concentration increased as the initial concentration of added Zn increased through the range 0 to 4 μm. Zinc was highest in seedlings grown in solutions with both high Zn and high P concentrations. High leaf P concentrations were associated with inadequate Zn nutrition.

Open Access

Application of high rates of P in the year of planting increased the number of flower clusters and fruit set the subsequent year on newly planted `Macspur McIntosh', `Summerland Red McIntosh', `Jonagold', and `Jonamac' apple (Malus domestica Borkh.) on dwarfing rootstock (M.26 and M.9) in three separate experiments. The effect occurred whether P was applied at rates of 36 or 48 g P/tree as granular monoammonium phosphate (11 N-23.6 P-0K) uniformly mixed with 100 or 180 liter of soil in the planting hole or at rates of 17.5 and 35 g P applied as soluble ammonium polyphosphate (10N-14.6P-0K) with the irrigation water. A leaf P concentration range between 0.20% and 0.36% was associated with the acceleration of fruiting.

Free access

The effects of various nonfumigant planting-hole treatments on growth and yield of apple (Malus domestics Borkh.) trees were measured during the first 3 years after planting. Eight orchards diagnosed as having a replant problem were monitored. First-year shoot growth, the number of blossoms in the second year (inmost orchards), and first-year trunk cross-sectional area increment (TCAI) in 50% of test orchards were increased by monoammonium phosphate (MAP) fertilizer+ peat, MAP+ mancozeb, or MAP + peat + a bacterial antagonist. By the end of year 3, TCAI generally was not affected by treatments, but treatments resulted in more blossoms by the third season in two of seven orchards that blossomed in the second season. Cumulative yield after 3 years increased significantly in only three orchards, with the best treatment, MAP+ peat, resulting in cost recovery in only one orchard. Inadequate K or Cu nutrition may have reduced growth in some of the orchards, which were characterized by a wide range in yields, independent of planting-hole treatment.

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Abstract

Mature ‘Golden Delicious’ apple trees (Malus domestica Borkh.) were subjected for 3 years to factorial combinations of 3 rates of N fertilization applied in April and 3 degrees of orchard floor management. Tree N nutrition was affected more by vegetation management than by rate of N fertilizer applied. Significant reduction in leaf N and trunk diameter, and superior fruit skin color and firmness at commercial harvest occurred consistently when the orchard floor was sod. Increased leaf N and reduced fruit skin color and firmness at harvest were measured at the highest N (180 kg N ha-1) in only 1 year while tree growth was not increased by this rate of N. Increased fruit Ca associated with smaller fruit and increased leaf Mg and leaf K were measured under sod in 2 of 3 years. Leaf Mn was affected only by rate of N fertilization and was consistently high at 180 kg N ha-1.

Open Access