Selecting Rootstocks to Your Soil Conditions

You do your best to select a site that is optimum for growing apples by looking for land that has an ideal soil type with good drainage, a gentle slope for air flow to prevent against frost and is located in an ideal climate zone. Quite often, it is difficult to find a site that has all of these qualities and the soil type can be variable within an orchard block. The M.9 is the most common rootstock in new high density plantings in Ontario but it may not perform as well in certain types of soil. When selecting your rootstocks keep in mind the soil type. In Table 1 are examples of some apple rootstocks and the characteristics of soil that they are suitable for.

In an experiment in pots by Fazio et al., Golden Delicious Smoothee trees were grafted onto over 30 different rootstocks and planted in sandy loam and clay loam apple replant soil that were either pasteurized (enough to kill soil borne diseases like apple replant disease) and unpasteurized. Over the first growing season, growth parameters were measured. Overall, most rootstocks performed better in clay loam than in sandy loam, except for B.9, G.214 and G.890 which preformed similarly in both soil types. B.9 was more tolerant to apple replant disease in clay soil than in sandy soil. G.16 was the opposite, where it was more tolerant to apple replant disease in sandy soil than in clay soil.

Table 1. Commercial rootstocks and their soil suitability
Adapted from Domoto, P. 2004. Characteristics of Apple Rootstocks
Rootstock Size Soil suitability
M.26 55-60% Intermediate to heavy well drained soil
Not recommended for light, course textured soils
It is fairly sensitive to wet soils
Not drought tolerant
May be too large for high density plantings on deep fertile soil
G.935 50-60% Well adapted to most soils
Ottawa 3 50-55% Well adapted to most well-drained soil
G.202 45-55% Well adapted to most soils
M.9 40-50% Intermediate to heavy loam, well-drained soil
Not drought tolerant
G.11 40-50% Well adapted to most soils
G.16 35-45% Well adapted to most soils
G.41 30-45% Well adapted to most soils
Mark 35-40% Well drained soil
Drought susceptible
Bud.9 25-40% Well drained soil
No tolerance to wet soils

Soil pH

In the previously mentioned experiment by Fazio et al., where one year's growth of Golden Delicious was evaluated on different rootstocks grown in pots, it was found that some rootstocks perform better in a certain pH range. The optimum pH for most rootstocks was 7.5. Nutrient uptake at varying pH was better in some rootstocks than others. In general, molybdenum, calcium and phosphorus uptake increased as pH increased. Iron, manganese and nickel uptake decreased as pH increased. G.41 had an unusually high iron uptake at a high pH; optimum pH for iron uptake in most rootstocks is between 4.5 and 6.5. G.41 also had higher phosphorus uptake, at pH 5.5 to 8.5, compared to other rootstocks. G.969 had the highest uptake of phosphorus at 4.5

Soil Compaction

It was demonstrated in an experiment by Ferree et al. that some rootstocks can tolerate higher bulk densities better than other rootstocks. 'Red Gala' grafted on to different rootstocks were grown in pots from April to November in a greenhouse with soil at bulk densities of 1.0 and 1.5 g/cm3. At a bulk density of 1.5 g/cm3, the total dry weight of M.26 was reduced. Total dry weight of B.9, G.16 and G.30 were not affected by the bulk density of 1.5 g/cm3.

It is important to note that these potted rootstock experiments may not extrapolate to field conditions but they do indicate that rootstocks do preform differently under different soil types, pH and compaction. This information may be one more piece of the puzzle to consider when selecting your rootstocks.

References

  • Domoto, P. 2004. Characteristics of Apple Rootstocks.
  • Fazio, G., D. Kviklys, M.A. Grusak and T. Robinson. 2012. Soil pH, soil type and replant disease affect growth and nutrient absorption of apple rootstocks. NY Fruit Quarterly 20(1):22-28.
  • Ferree D.C., J.G. Streeter, and Y. Yuncong. 2004. Response of container grown apple trees to soil compaction. HortScience 39(1):40-48.
  • Ward, D., W.P. Cowgill Jr., J.L. Frecon, G.C. Hamilton, J.R. Heckman, L.S. Katz, N Lalancette, B.A. Majek, D. Polk. 2014. "New Jersey Commercial Tree Fruit Production Guide." Rutgers Cooperative Extension Bulletin E002. 229 pp

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