Science into practice - Blackcurrant crop protection

Botrytis, leaf-curling midge and sawfly are economically damaging diseases and pests of blackcurrants. Botrytis not only causes grey mould of the fruit but can give rise to "run-off" in spring, leading to reduced yields. Leaf-curling midge stunts growth in shoot tips, slowing bush growth, while blackcurrant sawfly can lead to defoliation of the bush.

AHDB Horticulture part-funded Defra Horticulture LINK Project HL01105, which sought to develop novel control methods for Botrytis, leaf midge and sawfly.

The research on Botrytis identified a possible link between high nitrogen treatments and disease incidence in blackcurrants. Spray control trials also identified that the first three sprays applied from first flower are the most important treatments for Botrytis control. If an effective fungicide programme is applied at this time, then there is no benefit from additional fungicides near to harvest.

Work to examine the effects of supplementing flower pollination with additional Bombus terrestris nest boxes, particularly during poor weather, gave rise to increased yield and bigger fruit size. Guidelines for growers on how to enhance natural bee populations have been issued.

The project identified that control of blackcurrant leaf midge is most important in newly planted and establishing plantations (including those recently cut back), but control in established crops is less important providing there is adequate regenerative growth.

The commercially available sex pheromone monitoring trap can be used to successfully time sprays to control the midge. The project also identified and synthesised the female sex pheromone of the blackcurrant sawfly and a commercially available sex pheromone trap is now being developed.

The full grower summary for Project HL01105 is available on the AHDB Horticulture website at horticulture.ahdb.org.uk.

AHDB Horticulture

For details on all AHDB Horticulture activity, see horticulture.ahdb.org.uk


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