Aphelenchoides ritzemabosi and A. fragariae cause damage on ornamental crops. Ditylenchus dipsaci (stem/bulb eelworm) attacks bulbs and herbaceous plants alongside Meloidogyne spp. (root-knot eelworm). Nematodes cause feeding damage and can act as virus vectors.
A wide range of crops can be attacked, including Abelia, Aconitum, Anemone, Aster, Azalea, Bergenia, Begonia, Buddleja, Calceolaria, Campanula, Chrysanthemum, Cistus, Cornus, Dahlia, Delphinium, Doronicum, ferns, Fragaria, Geranium, Helichrysum, Helleborus, Hepatica, Heuchera, Hibiscus, Hosta, Hydrangea, Lamium, Lavandula, Lilium, Paeonia, Philadelphus, Phlox, Primula, Ribes, Salvia, Saxifraga, Scabiosa, Verbena, Veronica, Viola, Viburnum and Weigela.
Potato cyst nematode (Globodera rostochiensis and G. pallida) is a notifiable pest, easily spread by cultivation, with implications for growers using rented farmland for open-ground production.
Cultural controls and nursery hygiene are essential — nematodes are readily spread by overhead irrigation or propagation mist systems. The plant propagation chain is also a significant potential means of spread. Plant debris and weeds can also harbour infestations.
Note that some nematodes are beneficial. Heterorhabditis, Steinernema and Phasmarhabditis spp. will control vine weevil larva, sciarid flies or slugs.
How to recognise them
Tiny worms (1-2mm long) that, through a microscope, resemble eels (hence “eelworm”), with blunt heads and a mouth-spear in most plant-parasitic species. Female cyst nematodes swell to form spherical brown survival cysts, 0.5mm in diameter. Root-knot nematode cysts are pear shaped.
Symptoms
Aphelenchoides spp. Discoloured, angular blotches on leaves. Plant damage can be confused with downy mildew infections. Bud feeding leads to stunting and distortion of emerging leaves and flowers.
Ditylenchus dipsaci Infested bulbs are soft at the neck and, when cut across, show discoloured brown rings of dead tissue. Resulting growth shows as leaf and flower distortion.
Meloidogyne spp. Galls up to 2cm develop on roots, often irregular in shape. Plants show nutrient deficiency and wilting.
Treatment: biological control
Caliente mustards (from Tozer Seeds) can be sown prior to planting. These green manure mustards contain high levels of natural glucosinolates that form MITC — the sterilant released by some chemical fumigants — when chopped and incorporated into soil.
Eruca sativa (rocket) has high levels of glucosinolate in its roots and traps Meloidogyne spp. French marigold ‘Ground Control’ can be planted on fallow land. The marigold roots produce a powerful biocide that will kill the feeding pests.
Treatment: cultural control
Eelworm-infested stock plants of many herbaceous perennials can be cleaned up by hot-water treatment. Use the AHDB fact sheet 10/13 as a guide. Storing bulbs at 30°C for three weeks prior to treatment can reduce flower-damage risks too.
Leaf and bud nematodes can be transferred via cuttings and spread on propagation tools, dead and dying plant matter and poorly composted material. Avoid excessive moisture in propagation. Space plants to avoid leaf contact. Use approved disinfectants for tools, equipment and surfaces.
Control weed hosts including bindweed, buttercup, chickweed, cleavers, daisy, dock, groundsel, sow thistle, speedwells, chickweeds, fat hen and shepherd’s-purse.
Treatment: chemical control
Active ingredient: Fluopyram
FRAC code: 7
Formulation: Velum Prime* (Syngenta)
Action(s): Registered as a fungicide and nematicide. Harmful to most soil-based beneficials.
Active ingredient: Fosthiazate
IRAC code: 1B
Formulation: Nemathorin 10G* (Syngenta)
Action(s): Persistent, contact-acting nematicide. Compatible with some biological controls. Product comes in a specialised Surefill container for field hopper use.
Active ingredient: Garlic extract
Formulation: Pitcher GR* (ECOSpray/Everris)
Action(s): Contact nematicide requiring good soil/compost moisture. Compatible with some biological controls.
Fully updated by Dove Associates
Use plant protection products safely. Always read the label and product information before use.
* Extension of Authorisation for Minor Use (EAMU) required for use in ornamental plant production outdoors and/or under protection.
Dove Associates shall in no event be liable for the loss of or damage to any crops or biological control agents caused by the use of products mentioned.
