Site selection before planting an apple orchard
Choose fertile soil that drains freely and avoids waterlogging. Apples need full sun and a sheltered position, with protection from late frosts that can damage flowers. Match the rootstock's vigour and eventual tree size to the planting space.
Rootstock and root-zone depth determine the area that drip irrigation must wet.
Replant disease on former orchard ground
Apple replant disease can produce uneven growth, stunting and shortened shoot internodes after replanting. Leaves can be smaller and paler, while roots show tip necrosis, discolouration and reduced biomass. The severity varies between sites.
The disease complex includes fungal and oomycete pathogens and nematodes. Soil structure, fertility, pH and environmental conditions also affect young-tree growth.
After grubbing the old orchard, remove old roots and other plant residues promptly. Consider planting in former alleyways, with weeds controlled before the new trees are planted. Review the previous rootstock: genetically different and more vigorous combinations can be less affected by replant problems.
Rootstock, pollination and planting material
Rootstock controls tree vigour and size. This applies to a small apple orchard as much as to a large plantation. Match variety flowering times for pollination, or choose a self-fertile variety suitable for the intended production.
Plan irrigation for the crop's root distribution and soil variation. Lighter and heavier areas may need separate irrigation units. The drip-design guide covers wetted area, filtration and flushing access.
Apple tree pesticides: safe insecticide for fruit trees, apple tree insecticide spray and codling moth timing
Codling-moth control must reach newly hatched larvae before they enter the apple. Larvae bore into the fruit flesh, leaving an entrance partly blocked by dry frass.
Sex-pheromone mating disruption provides a non-spray control mechanism. Avoid pyrethroids where they would harm predatory mites and other natural enemies in the orchard, whichever insecticide you consider for fruit trees; the label still sets the conditions of use.
NIAB's apple assessment guide gives pest-specific sampling methods and thresholds.
Codling moth attacks apples and pears. Larvae inside the fruit are a different target from newly hatched larvae still outside it. Time an insecticide for apple trees to egg hatch and new larval entry.
First-generation adults emerge from May to July and fly at dusk on warm evenings. Eggs are laid singly on foliage or fruit surfaces. Egg development depends on temperature, so egg-laying and hatching fall at different dates.
Monitor codling-moth pheromone traps weekly from petal fall until harvest. For the first generation in May–June, the intervention threshold is a catch of five or more moths per trap per week. For the second generation in August–September, it is three.
Woolly aphid in the orchard
Woolly aphid is a pest to deal with through the orchard itself first. Natural enemies play an important part in regulating its numbers, and the common European earwig is an important predator that often prevents damaging infestations from developing. Give earwigs a refuge in the tree, ideally one in each tree: a few extra lengths of hollow tree tie round the stake will do. In May and early June the colonies are still localised on the trunk, and a scrubbing brush destroys them before they spread to young shoots, which is practical on a limited scale or where tree density is low.
The parasitic wasp Aphelinus mali contributes to regulation as part of a complex of natural enemies, but it is rarely able to control the aphid alone in the field. Buying predators or parasites from a biological control supplier is unlikely to be economic. If the wasp is absent from your orchard, it can be introduced from another orchard by placing branches that carry parasitised aphids near woolly aphid colonies, in good weather in early summer.
Keep your spray records in one place. Free to start.
What you spray decides how many of these helpers survive. The adult parasite is sensitive to broad-spectrum insecticides such as chlorpyrifos or synthetic pyrethroids, and residues on the bark are probably harmful to it for a considerable period after spraying. Repeated contact and fungicide products with wetting-agent formulations can also have sublethal effects on earwigs, and minimising spray applications gives them a better chance of increasing. If a woolly aphid insecticide still turns out to be needed, choose a product whose label lists apple and the pest, and look it up in the HSE register before you buy.
Plums and pears need their own identification
A moth larva inside a plum is not automatically codling moth. Two moth species have caterpillars that feed in plum fruit. Plum fruit moth feeding can leave a large cavity filled with brown frass.
Use species-specific pheromone traps to monitor male plum fruit moths.
The product documents set crop tolerance, operator precautions, pollinator protection and residue restrictions for any insecticide for fruit trees. Find them through the HSE register.
Distinguish plum fruit moth, fruitlet mining tortrix and sawfly
Plum fruit moth is Grapholita funebrana, also known under the synonym Cydia; fruitlet mining tortrix is Pammene rhediella. The former commonly feeds on blackthorn or sloe and can attack cultivated plum and damson. The latter also feeds on hawthorn berries and occurs more sporadically in plum.
The plum fruit moth larva usually feeds alone within a fruit, leaving a cavity filled with brown excrement near the stone. Infested fruits may ripen prematurely. Plum sawfly, Hoplocampa flava, can cause superficially similar damage earlier, while fruitlets are smaller, with a more conspicuous hole and wet black frass.
The plum moth adult is slate-grey with indistinct forewing markings. Eggs are translucent, flat and roughly circular. A young larva is initially white with a dark head, later becoming reddish. After feeding, larvae leave fruit and make silken cocoons in bark crevices or similar shelter; pupation normally occurs the following spring, although favourable summers can allow a partial second generation.
Fruitlet mining tortrix damage differs in the quantity of gum that leaks from the wounded area and gathers in surrounding webbing. Its burrowing larvae leave little or no frass in the flesh compared with plum fruit moth.
Codling-moth granulovirus provides a biological control directed at codling moth. It does not control tortrix moths, blastobasis or unrelated orchard pests. Time the treatment just before egg hatch so larvae encounter virus particles before boring into apples.
Organic and preventive options
Before choosing an organic pesticide for fruit trees, check the product authorisation and the control body’s organic-production rules. Organic pest control also includes monitoring, mating disruption and other non-chemical measures.
See the organic-input guide and drip design guide.
High density apple orchard: tree density, rootstock and yield
Growers plant anything from 200–300 trees per acre on semi-dwarfing rootstock with a central leader, up to 500–1000 trees per acre on dwarfing rootstock with some version of vertical axis, and a few plant 2000 trees per acre as super spindle. A high density apple plantation in the tall spindle style is about 3,260 trees per hectare (3 ft by 11 ft) on M.9, G.41 or G.11 rootstock, and the super spindle about 5,380 trees per hectare; a vertical axis orchard is about 1,540.
Density drives yield per hectare. In a long-running trial the highest-density system reached 50 t/ha in its fourth year while the lowest-density system did not pass 25 t/ha, and over seven years the cumulative yield per hectare of the highest density was three times that of the lowest. The price is smaller trees: on M.9 the highest planting density gave trees about a third the size of the lowest density, and yield per tree fell as density rose.
For high density apple farming, choose the rootstock and the system together before planting and set the sprayer for a narrow, tall canopy; the treatments, drift checks and spray records in the sections above apply per block as in a looser orchard.
Next step
Use NIAB's pest and disease assessment, find the label in the HSE register guide and check organic acceptance where it applies.