Ensure timely application of nutrients and "friendly" pesticides, cider growers told

A planned nutrient programme is key to optimising cider apple yields and quality, something often overlooked by growers, Agrovista fruit agronomist Jane Antrobus told the agronomy company's cider technical seminar in Ledbury, Herefordshire.

Image: Putneypics (CC BY 2.0)
Image: Putneypics (CC BY 2.0)

"Traditional cider orchards were often left to fend for themselves, and that thinking prevails in many newer orchards too," she said.

"While the soil is an amazing tool to hold nutrients and produce crops, and the tree itself can hold a large amount of reserves, each year the crop does take nutrient away and this needs to be replenished."

Adequate nutrient supply strengthens the tree’s vitality for continual cropping, underpinning yield potential and improving the tree’s ability to handle pest and disease pressures, she explained.

Soils should be maintained at pH6.3-6.8 to optimise nutrient availability, while nutrients should be applied at the right time and in the correct quantities, avoiding excessive concentrations of certain nutrients that could antagonise uptake of others, she added.

Nitrogen applications should be spread over the season, beginning at bud opening or early flower bud to aid petal production and boost tree vigour, and repeated at fruit set to boost cell division on fruitlets. The third application should be made as fruit develops to encouragers cell expansion, she said.

"The first two applications should be made using ammonium nitrate fertilisers to ensure a spread of N release, but the third needs to be nitrate only as this is immediately available to the tree at this late stage of the season."

Application of micronutrients also needs to be tailored to expected lows through the season, so for example boron and zinc are in high demand at flowering, while magnesium levels are known to fall after flowering.

Antrobus recommended FiloCal, which came in three formulations – Red Calcium, containing calcium and magnesium, Black NPK and Micronutrients and Blue Micronutrients.

Paul Bennett, Agrovista’s technical head of fruit, then explained how beneficial insects have an increasingly important role to play in apple orchards as the pesticide armoury continues to decline - something which should be borne in mind when planning spray programmes, which should maximise the use of target-specific chemistry rather than broad-spectrum products.

Active ingredients, especially insecticides, are being lost to the sector "at an alarming rate", Bennett warned. "With no Aphox or chlorpyrifos available now, control of some pests such as the woolly aphid has become extremely difficult, so beneficials are becoming even more valuable."

Key beneficials include ladybird, lacewing and hoverfly larvae, parasitic wasps and assassin bugs, but the most valuable of all was the earwig, which Bennett described as "probably the premium predator – it will eat almost anything", adding: "It is nocturnal so you may not notice it, but it is present in many orchards in large numbers."

Products such as Decis, Dimilin, Insegar and Tracer are non-selective and should be avoided where possible, he said. Calypso and Gazelle are less harmful to non-target species, but products like Mainman, Steward, Trotter Apollo and Masai are much more target-specific and so have less effect on beneficials.

Any spray should be applied only when needed, such as when thresholds are exceeded or where orchards have a history of a pest problem and damaging attacks are almost certain, Bennett advised, adding that accurate timing is key, so that sprays coincide with maximum pest activity to optimise control.

Key periods in theis regard include bud-burst to control apple blossom weevil, green cluster for codling and tortrix caterpillars, pink bud to eliminate rosy apply aphid, and petal fall to control apple sawfly. These may be followed up in June by a spray to control ermine moth caterpillars and in July to control scale and woolly aphids, he suggested.

A typical beneficial-friendly programme would consist of Calypso at budburst, Trotter at green cluster, Mainman at pink bud, Calypso at petal fall, Trotter in June and Gazelle in July. This need not exceed the cost per hectare of a more broad-spectrum approach, such as using Decis at first and last timings and Tracer at the second and fifth timings, he added.

"Using broad-spectrum insecticides does not cost less and is likely to result in an increase in pests due to the damage caused to beneficial populations," said Bennett. "Long-term this could mean pesticide use goes up, underlining the importance of selecting the right products in the first place."

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