The Groundsman

January 2016

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TECHNICAL UPDATE 29 the Groundsman January 2016 Visit www.iog.org for more information and digital editions Cool season turf It's only during the past 15 years that the real importance of the parasites on cool season turf grasses has been recognised, but certain species have long been associated with devastating losses in warm season turf. So, why is it that in cool season turf these parasites are apparently only now causing problems, or have they always been present, but simply overlooked? Low numbers of PPN are frequently found in amenity rootzones and if the plants are growing strongly, these small populations will have a minimal effect on turf quality. However, if there are accumulated abiotic stresses on the turf, the observed effect due to PPN infection will increase. For this reason, it is important to be aware of the presence of these PPN in any amenity area and work to minimise abiotic stresses by keeping the plant strong and healthy. Consequently, there are several possible reasons for the apparent rise in occurrence of PPN and it's likely that the most common reason is that we are now looking for them; before we knew they posed a potential threat, we weren't routinely assessing for them and therefore their presence could well have been overlooked. Certain PPN species form large galls or swellings on the roots and this abnormality should be quite clearly seen with a x10 hand lens. However, the specific cause of the root swelling can only be confirmed once the galls or swellings have been examined more closely using a microscope. Mistaken identity In 2001, the observation of significant root galling was the first real indication that PPN were actively causing disease on fine turf grasses across the UK and Ireland. For several years prior to this, the associated symptoms of distinct chlorotic patches on golf course putting greens had been incorrectly considered due to fungal disease. However, once the actual cause was confirmed, the Root-knot nematode Meloidogyne was found to be common in many turf grass rootzones. Several species of Root- knot nematode are now known to cause disease in turf across the UK and Ireland, with additional species affecting turf grasses worldwide. Initially, the occurrence of Meloidogyne spp. had been considered an accidental introduction, most probably on golf shoes, as the infections appeared to be restricted to golf course putting greens. However, research has subsequently confirmed that these PPN are native species, naturally present in the UK and Ireland that have taken advantage of the ideal conditions of many high sand-content rootzones in which to build their populations. This opportunistic increase in nematode populations would appear to be the case for the majority of identified PPN related problems. However, there are several additional reasons for the apparent rise in PPN occurrence in turf. Many turf facilities now use sands or high sand content rootzones either for construction or during maintenance. These materials not only provide what is generally considered to be the best turf grass rootzone for quality planting surfaces, but also the ideal conditions in which PPN populations can increase, Damage to the turf grass plant can be seen as root swellings or abnormal root development. Damage on the sward's root structure shows as a chlorosis or wilting of the leaf t

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