Nematode Control and Seaweed Extract
It is essential to note that seaweed extracts are not nematocides and can only offer the possibility of some degree of protection against nematode attacks. However, it is worth mentioning that a nematocide has been produced from seaweed extract plus other “natural substances”, although it is not available in Europe.
Laboratory research work has shown that nematode populations can be reduced when plants are drenched with seaweed extract on a regular basis (once a week). Similar results have been achieved when the plants are treated with a drench of betaines, active ingredients found in seaweed extracts, including Chase SM6. Where drenches are applied there is clear contact between the nematodes and the seaweed extract.
Foliar sprays with seaweed extract have also had beneficial effects on various crops (including potatoes) and amenity grass. In this situation there is unlikely to be significant direct contact between the nematodes and the extract, but as yet the crop response is not fully explained. One possibility is that the treated plants generate more roots, thus counteracting the nematode attack. An alternative suggestion is that active ingredients within the seaweed extract stimulate the plant’s natural defences inhibiting nematode penetration of the roots or, through the root exudates, inhibiting nematode activity.
Where nematode attacks are expected within potato crops and chemical nematocides are not an option it may be worth considering:-
- Drenching the seed immediately prior to planting or within the row prior to covering, using 1 part SM6 in 200 parts water.
- Introducing an earlier spray as soon as there is adequate leaf cover, preferably using a higher volume of water.