Eelworms are a pest, but for practical purposes, they can be treated like an incurable disease of plants.
The Eelworm Nematode is invisible to the human eye - in most cases. It is only the result of their damage that we actually see, and there is no treatment available to the amateur gardener, so best to remove the infected plant and burn. In many instances it also means no planting of the same type of plant in the same area for many years.
The damage from eelworm infestation does not become apparent until late summer and into the autumn, when leaves of various perennials and shrubs mysteriously turn black - and sometimes yellow with no visible reason such as aphids, fungus or anything else that can be blamed!
Experienced horticulturist will shudder at the description just given. Fine. That's how it can best be described to the amateur. Many professionals are also flummoxed as to what has hit their plants as well, so don't worry!
The main recipients of Eelworms are notably Chrysanthemums, Penstemons, Phlox, Gypsophila and Anemones. Strawberries have their own eelworm - or nematode as they are known! (A little bit confusing, because there are also useful Nematodes - often sold as biological control for such things as slugs and leatherjackets etc.)
If ever there is a discoloured or distorted leaf or flower with no obvious signs of pest or disease, then Eelworms must be suspect. On plants where eelworms are known problems, such as Chrysanthemums, then overhead watering should be kept to minimum, because this facilitates the movement of the eelworm on the exterior of the leaf.
Nematodes sometimes cause growth on roots of some plants. Nematodes are also the cause of many parasitic problems on humans and animals - also fish.
Stem and Bulb eelworm are also responsible for damage to bulbs and corms including Daffodils, Tulips and Hyacinths. the tell tale signs are soft - rotten - bulbs, and small yellowish swellings on the foliage - especially with Tulips. (Not to be confused with Rust.) Again, the control is dig up and burn, and not replant with the same type of bulb in that area for at least four years.
Typical Nematode nodules on Root of plant.
There is a method of hot water treatment for chrysanthemum stools for those wishing to take cuttings from Chrysanthemums - affected plant.
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