In most cases, the best place to remove a turf sample for analysis is from the leading edge of the symptoms
identify the problem. In most cases, the best place to remove a turf sample for analysis is from the leading edge of the symptoms, where the affected or discoloured plants give way to healthy turf.
It is also important for the lab to be able to see what the general composition and condition of the sward is like and what the rootzone profile is like and, for those reasons, a 90mm diameter core sample, taken to a depth of approximately 60mm using a golf hole changer (or similar) makes for an ideal sample. The turf core should be kept intact by wrapping it tightly in dry newspaper and packing it in to a box for posting. Next day delivery can be guaranteed and the sample should arrive at the lab in good condition for analysis. If the symptoms develop rapidly on the turf area, any lab would appreciate you sending two or three turf samples to show the different stages of development, but they should only charge you for one analysis - after all, it’s only one problem that they are investigating for you.
If possible, email some photographs of the symptoms so that the lab can get an idea of how the problem is developing - a good picture can often tell so much more than a detailed written description. If you have provided the best possible sample for analysis, the least that you should expect from any lab is that they provide the best possible analysis service, i.e. a rapid, accurate and complete analysis. Many of the fungi that cause disease on turfgrasses produce mycelial characteristics and spores, in addition to the visible symptoms on the plants, which will aid identification of the problem. Care must be taken by the lab not to
merely identify the presence of a fungus but to determine whether that fungus is actually causing disease and that is where the problem lies, especially with labs that specialise in areas other than amenity turf. Many fungi that cause disease in turf
also exist quite happily as saprophytes at the base of the sward and feed on the dead and decaying material. I would bet that you can find Microdochium
nivale, for example, in all turf but does that mean that it’s always causing disease? No! Disease identification should include observation of the affected plants and the symptoms on the leaf, stem, crown and root tissues, identification of the fungi that are actively present, recognition of the environmental conditions and an appreciation of how the symptoms have developed since they initially appeared. There are a few fungi that cause disease but don’t produce spores and, without spores, the identification of the fungus becomes more difficult. Fungal spores are like the fingerprint of a fungus. Different fungal genera will produce different shaped, sized and coloured spores and, within each genus, the spores of the different fungal species will show characteristics that allow them to be further identified. Without spores, a lab will have to rely on information relating to the prevailing conditions, the symptoms on the plant, the grasses affected and the mycelial characteristics of the fungus to help with identifying the problem. The fungus can be grown on an artificial medium in the lab but this takes time and, without the additional backup of DNA analysis on the isolated fungi, the analysis result may be more tentative. Fortunately, this does not cause a
problem very often, as many of these non-sporing fungi grow differently on specific culture media and they can be identified once the fungi are grown. The concern that I have is that these fungi tend to cause disease rapidly and spread quite quickly so, waiting for the fungi to be isolated and grown up in the lab, could mean that the turf has suffered significant damage by the time the result is provided.
Disease analysis all sounds relatively straightforward, so what could go wrong? Frequently, samples are received with no sender details so the results can’t be forwarded until someone calls in to see where the result is.
Turf samples are packed too loosely and get thrown around in the post. The sward becomes covered with rootzone which speeds up the decay of the turf, the sample becomes broken apart, different samples within the same outer
box get mixed up so we don’t know what sample we are analysing. Bulked tine cores are received for identification of a foliar disease. Tine core samples contain very few intact plants and, without intact plants, a root problem cannot be ascribed to a grass type in a mixed sward. Worse than that, the plant material begins to decay as soon as it is severed from the roots and, by the time the plants reach the lab, the initial symptoms of disease may be masked by decay. Bulked tine core samples should only be sent if the rootzone is to be checked for plant parasitic nematodes. For this type of analysis, tine cores are ideal because they can be bulked from across and around the affected areas (and a similar sample should be sent from a healthy area for comparison) providing a more representative sample than a single core.
That said, not all labs will check for
the presence of plant parasitic nematodes, so it is worth asking before you make the effort to send the samples.
Different labs will use slightly different methods
Different labs will use slightly different methods to analyse the turf for disease, and these methods will have been determined by the staff in relation to the quantity of material that they have to analyse, the quality of the received samples, the requested analysis and the cost of the work. However, the different labs should
provide the same result - the cause of the damage to the turf. In some cases, symptoms on received turf samples can resemble those of certain diseases but, following analysis, the cause is found to be physiological or related to the local conditions or recent applications. In such circumstances, the best result that can be achieved from a disease analysis is confirmation that the problem is not caused by a fungus or parasitic nematode and, if necessary, a referral to laboratories that will be able to check for certain other causes should be provided. The different methods employed by labs will inevitably produce slightly different results, but this is not in itself
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