Managing vine weevil in container-grown nursery stock
Vine weevil is the number one pest of container-grown hardy nursery stock.
Adults cause damage by feeding on and notching the foliage of plants, but the larvae, which feed on the roots of plants, crowns, corms and rhizomes can cause severe damage which can result in the death of the plant. Feeding symptoms or the presence of larvae in the plant rootball can result in product rejection.
Due to the withdrawal of, and restrictions on using most persistent plant protection products in the growing media for control of vine weevil larvae, a robust integrated pest management strategy is now needed, tackling both adults and larvae.
AHDB Horticulture is funding project HNS 195 ‘Improving vine weevil control in hardy nursery’, which is testing: a ‘little and often’ approach to nematode application through overhead irrigation; the potential of cold tolerant strains of the fungus Metarhizium brunneum (anisopliae) for vine weevil larvae control; and attempting to identify attractants for potential use in adult monitoring traps and for use in a ‘lure and kill’ approach to the pest.
Managing vine weevil in soft fruit
Vine weevil has been one of the principal pests of soft fruit crops in the UK for several decades. In the 1980’s, the pest became a more persistent problem in soil grown crops which were planted through a polythene mulch as the warm and moist conditions which prevailed under the mulch favoured the survival and development of the pest. The mulch also offered a perfect refuge to the weevil from predatory birds, whilst also making it more difficult for control measures to reach the pest.
In the past decade, in strawberry and raspberry production, there has been a major shift in the way the crop is produced, moving from cropping in field soils to production in soilless substrates in containers (bags and pots). In the majority of production, coconut fibre (coir) is used as the substrate. Although vine weevil continues to cause a major threat to container grown strawberry and raspberry, growers have had more success in controlling it in this production system, using predatory nematodes which are applied through the drip lines which are used to irrigate the crop. Control in soil grown crops continues to prove more difficult.