Nematodes are an extremely diverse group of
unsegmented roundworms that can quite correctly be regarded as invertebrate pests. However, they are also microscopic, directly attack the plant tissues, cause adverse changes to the physiology of the plant and initiate the
with the rootzone and masks any potentially reportable problems that may have been apparent down the profile. For fungal disease
Patch Sample
Patch Disease Sample
development of disease. Therefore, like fungi, they can also be regarded as disease-causing organisms. With regard to sampling for nematode analysis, they will be considered separately from other invertebrates and from the fungi that cause disease. Generally, if your turf is being colonised by invertebrate pests, you can find them living in the rootzone but you may not necessarily know what they are. If this is the case, gather up a few of the larvae and put them in to a sturdy (preferably plastic) container, something like the old 35mm film cases is ideal, and fill the rest of the container with rootzone or plant material to prevent the larvae from being shaken around too much whilst in the post. Putting several of these invertebrate larvae in a plastic bag inside a normal envelope is not a good idea as they arrive at the laboratory more like an invertebrate soup than any living creature - I have received them like this so I know. It is also acceptable to send a turf sample taken from an affected area, such that the larvae will be contained within the naturally infested turf or rootzone. In this case, the sample should be packed tightly in to a cardboard box or padded envelope for postage. For some invertebrate pests like the frit fly larvae that are much more difficult to see, I would recommend that you send a hole changer sized turf sample, with rootzone down to approximately 50 mm (2 inches) so that the laboratory can check for the presence of the pest larvae using a microscope. A hole changer core sample is also ideal if you think that your turf problem is likely to be a fungal disease. This size of sample shows what grasses are in the sward, which grass type(s) is(are) affected, provides numerous intact plants for analysis and allows a greater chance that the sward will remain uncontaminated by the rootzone material during postage. The core should be taken to the depth of the roots (or 150 mm (6 inches) max.) but not less than 50 mm (2 inches). However, where you decide to take the sample from is equally important. If the damage to the sward is developing in obvious circles or patches, it is best to take a core sample from the leading edge of the symptoms, such that half of the core shows damaged turf and half shows the unaffected turf around the outside. If you are in any doubt, or if the symptoms change noticeably over time,
problems, it is imperative that the turf sample is not wrapped in plastic. If the sward is in contact with plastic, it will sweat and secondary, saprophytic organisms are likely to flourish
and mask the presence of the primary pathogen. The turf should be wrapped tightly in dry newspaper and then packed in to a box or a padded envelope (the smallest necessary to contain the sample) and sent by next day delivery or by first class post. To help in confirming the diagnosis, it is always useful to include a brief history of the problem; age of sward, grass type present, when the symptoms were first seen, how they appeared and how they have developed over time, what products
send more
than one core sample
and indicate to the laboratory that they are all examples of the same disease problem. However, if the symptoms are more general across large areas of the sward, take one or more representative samples randomly from the turf. Hollow tine cores are not suitable for fungal disease analysis because they provide very few intact plants, don’t show how the problem appears on the sward and don’t give a clear impression of sward composition or the grass type affected. Occasionally, soil profile samplers are used to remove material for fungal analysis. This type of sample is acceptable if it is not possible to take a hole changer core from the area. However, you have to be aware of the limitations in analysis that can be completed on this type of sample. As with the hollow tine cores, many of the plants in this type of sample will be severed from the roots and the number of intact plants available for analysis will be reduced. Due to its size, this sample is more likely to fall apart whilst in the post, allows contamination of the sward
If you are in any doubt send more than one core sample
Sample not suitable for fungal disease analysis
were applied prior to and following symptom expression and if this is the first time these symptoms have been seen on the turf. It is extremely helpful for the laboratory to see a picture of the problem as this gives a clearer indication of symptom development than any description could ever provide. If possible, email a picture of the problem to the laboratory and inform them that you will be sending a turf sample for analysis. Problems caused by plant parasitic nematode are being reported more frequently as our understanding increases about the potential of these invertebrates to cause damage to a range of amenity turfgrasses. The symptoms that these pests can cause will vary dramatically depending on the type of nematode present, its current population and the type of grass being affected. However, analysis of turf or rootzone material for the presence of plant parasitic nematodes is best completed on bulked hollow tine core samples taken to a depth of at least 50 mm (or the depth of the roots) and packed in to a sealed plastic bag. The total mass of bulked cores should be about 0.25 kg and ideally, two samples should be sent. One sample should contain cores removed from affected areas of the turf and the other should contain cores taken from apparently unaffected turf that will allow background nematode populations to be determined.
It is possible for plant parasitic nematodes to be present within the rootzone, or inside the plant, at levels that are too low to cause damage. For this reason, it is important to determine the background population level against which the populations in the affected sample can be compared. It is crucial that the nematodes don’t dry out whilst they are in the post and it is for this reason that they need to be in a large enough mass of rootzone and contained
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