Preparing for Planting the New Apple Orchard
Preparing the site: It usually takes 1-2 years to get a field ready for planting. This is the time to improve drainage (Figure 1) , add organic matter (cover crops, manure), adjust soil pH with lime if required, apply phosphorus, and control perennial weeds (which may take 2 to 3 years).
Weed Reduction / Avoidance in the Preplant Year: Select fields with low weed pressure, or use a crop rotation that reduces weeds (e.g. field corn, winter cereals or green manure crops). Control perennial weeds with a 2 year strategy, targeting the most sensitive growth stage e.g. early bud in thistles, flowering in vetch (Figure 2). Plant a cover crop to smother weeds, especially in the fall before planting - this will prevent winter annuals from establishing. Use herbicides to control weeds in cover crops e.g. 2,4-D in wheat, or glyphosate in the spring to kill the cover crops. Mow weeds before they go to seed, especially around the field edges and in neighbouring ditches. If desired, sod can be established in the previous year and rows burnt out with glyphosate or flaming - ensure a weed-free strip at least 1.5m wide to avoid competition from the sod. Caution: Avoid herbicide residues by choosing low rates or non-residual herbicides.
Before Planting Trees in the Planting Year: Choose between tilling to prepare the planting row OR using a burndown herbicide to clear early weeds. Assess your soil organic matter (OM) level - a 2% OM is required to safely use most soil applied herbicides. In Ontario, if soil OM > 2%, Sencor, Treflan or Bonanza, or a tank-mix can be incorporated before planting (PPI) to reduce weeds.
For orchard replant sites, it might take more, maybe up to 5 years. Fumigation (Figure 3) has been shown to significantly reduce or eliminate ARD at most sites, but fumigants may not be available in the future. Here are some tips when replanting an old orchard site:
- Remove old roots.
- Test the soil for nutrients, soil pH and nematodes prior to planting A DNA Multiscan is now available for multiple organisms.
- Rotate to non-host crops. Leave the site fallow, plant an annual crop or cover crop helps reduce pathogens.. Brassica cover crops such as Oriental mustards (Figure 4) contain toxins that are released when chopped green and immediately incorporated to kill soil pathogens.
- Improve soil drainage. Installing tile drains will reduce the potential of standing water for prolonged periods and the risk of spread of Pythium and Phytophthora.
- Select tolerant rootstocks, especially to Phytopthora spp. (eg. G65, G30, G16, G11, G202). M9 and seedling rootstocks have some Phytophthora resistance where as M26, M7, M104 and MM106 are moderately to very susceptible.
- Improve soil health. The addition of properly composted manures and growing cover crops such as pearl millet (Figure 5) will significantly improve soil structure, provide additional organic matter and improve water permeability.
When to plant: Trees do best when planted as early in the spring as possible. Early planting will allow them to initiate new roots before the heat of the summer arrives. Wait until the soil is in good condition, not too wet, and when soil temperatures begin to rise. New roots will form when soil temperatures reach 7°C, and existing roots start to grow at temperatures lower than 7°C.
Ideally, the site was well prepared the previous fall, with only row marking (Figure 6) to be done. Communicate with your nursery to ensure that trees arrive early in good condition. Use a tarp and water pails to ensure that roots stay moist.
Fall planting can be successful in southern Ontario, but trees must be dormant before they are dug, with planting completed as early as possible after leaf fall to allow roots time to grow. Watering after planting is critical to ensure the trees stay hydrated through the winter.
What to plant: Inspect nursery trees on arrival, especially for damage, disease or insect pests. Crown gall, root rots, cankers or storage molds may be found on the roots or bark. If trees are not in good condition, contact the nursery immediately. It is better to return diseased or infested trees than to take a chance on your investment.
Be prepared to store trees if weather turns inclement. Trees need to be maintained in a dormant condition, and roots need to be moist at all times. Cold storage is excellent but make sure it is free of any ethylene gas from previously stored apples. Ethylene can severely damage new trees and prevent budbreak (Figure 7). Heeling in the roots in a trench outside is preferred to common barn storage.
Before planting, trim off excessively long roots, and damaged or dead roots. The goal is to maintain the root-to-shoot ratio. The advantage of well feathered trees may not be lost if excessive root loss happens from digging and replanting.
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