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Stellenbosch, South Africa

Stassen P.J.C.,Horticulture | Wooldridge J.,Soil and Water Science | Booyse M.,Biometry Unit
Acta Horticulturae | Year: 2014

Nectarine orchards were established on nematode-infested, sandy (>90% sand), slightly acid (pH 5.8, KCl) soils in the northern peach producing region of South Africa. 'Alpine' scions on 16 different rootstock cultivars were evaluated over three, three and 6 harvests after the orchards were established in 2009, 2008 and 2000, respectively. Trees on Flordaguard gave higher average and cumulative yields than on all other rootstocks in the 2009 and 2000 orchards, but did not differ (at P = 0.05) from Cadaman in 2008. Yield efficiencies on Flordaguard were higher than on Cadaman, Guardian, SAPO 778 seedling and Kakamas in 2008, SAPO 767, Penta and Tetra in 2009, and SAPO 778, SAPO 778 seedling, Nemared, Cadaman and Adafuel in 2000. Fruit weights from trees on Flordaguard and Atlas were high and did not differ, but were low for trees on GF 677 and Kakamas seedling in 2008, Penta and Tetra in 2009 and Ferciana in 2000. Trees on Kakamas seedling consistently produced lighter fruit than on Atlas. Trees on Flordaguard promoted large trunk circumferences compared to trees on GF 677 and Kakamas seedling in 2008, Kakamas seedling, Penta and Tetra in 2009, and Kakamas seedling, Viking, GF 677 and Ferciana in 2000. The 'Alpine' nectarine trees perform well on Flordaguard rootstock in sandy soils with low to medium numbers of ring and high numbers of root-knot nematodes. Source


Wooldridge J.,Soil and Water Science | Fourie J.,Soil and Water Science | Joubert M.E.,Soil and Water Science
South African Journal of Plant and Soil | Year: 2013

Effects of integrated production (IP) and organic-acceptable soil surface management practices were investigated in a Cripps Pink/M7 apple orchard in the Elgin area, South Africa. Work row treatments included cover crops, weeds and straw mulch. In the IP tree rows, weeds were controlled with herbicide and nitrogen (N) was supplied in inorganic form. Tree rows in the organic treatments received mineral nutrients in compost, and a straw mulch was used to control weeds. Tree and soil parameters were determined over a seven-year period. Compost usage in the organic treatments led to high soil phosphorus (P) and potassium (K) concentrations, but less acidity, than in the IP treatments. Stem circumferences, pruning weights and root numbers were generally greater in the organic than the IP treatments. Conversely, yields and yields per cm2 stem area were mostly lower in the organic, than in the IP, treatments. To improve yields in organic apple orchards the balance between vegetative growth and flowering and bearing structures must be improved, mainly through better control over orchard nutrition. Such control will be facilitated if composts are standardised with regard to mineral nutrient contents, ratios between N, P and K, and delivery rates. © 2013 Combined Congress Continuing Committee. Source


Wooldridge J.,Soil and Water Science | Fourie J.,Soil and Water Science | Joubert M.E.,Soil and Water Science
South African Journal of Plant and Soil | Year: 2013

Effects on soil, leaf and fruit element concentrations of organic (compost, straw mulch and hand weeding) and integrated (inorganic fertilisers and herbicide usage; IP) soil surface management practices in the tree rows, in combination with weed covers, cover crops and straw mulch in the work rows, were investigated in a seven-year trial. The trial took place on a gravelly soil in a Cripps Pink/M7 apple orchard in the Elgin area, South Africa. The organic treatments promoted higher phosphorus (P) and potassium (K) concentrations in the soil, leaves and fruit than the IP treatments. Leaf and fruit nitrogen (N) levels were normal in both the organic and IP treatments. Compost application rates that supply adequate N therefore deliver excessive amounts of P and K. Use of such composts should be based on P and K contents, supplementing where necessary with N. In both the IP and organic treatments, element concentrations were higher in the tree rows than the work rows. Treatments applied to the work rows did not affect soil and tissue element concentrations consistently. Standardisation of compost composition is required, as is balanced delivery of N, P and K. © 2013 Combined Congress Continuing Committee. Source

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