Unfortunately, nematodes are microscopic and, in many cases, it is impossible to confirm if you have a problem without a laboratory analysis
damage in turfgrass may be soil temperature. Hotter summers and warmer winters have been the norm around the British Isles. Higher soil temperatures favour nematode reproduction and activity, and nematode damage is usually less common in regions that experience significant periods of frost. It may also be no coincidence that some of the most serious nematode damage seen in turf has been on pitches where there has been regular winter use of under soil heating.
So, assuming that these pests are becoming increasingly important, how do you know if you have a nematode problem? Unfortunately, visible nematode symptoms in turf are fairly general and non-specific, which means it is usually impossible to confirm the presence of nematode damage without a laboratory analysis of the plants and rootzone. The nematodes themselves are microscopic and distinguishing the pests from the beneficial nematodes can be technically demanding and a job for the expert.
A look at the way nematodes actually affect plants can help understand the range of symptoms seen in turfgrass. Two major types of nematode parasitise
turfgrass: ectoparasitic species migrate along root surfaces, feeding on the root cells.
Endoparasitic nematodes actually enter
the root, where they migrate through the plant, before starting to feed. Some specialised endoparasitic species such as Meloidogyne (root-knot nematodes) establish and maintain complex feeding sites around the plant vascular tissue, but both ectoparasites and endoparasites can manipulate root morphology and physiology to support their parasitic way of life.
Consequently, nematode feeding causes different types of injury to plant roots:
• Reduction in root biomass (roots become shallow and sparse)
• Plant cell destruction • Root lesions • Abnormal root morphology • Knot-like galls and root distortion
• Secondary infections by other pathogens
Equally important are the physiological effects seen in plants:
1.Energy demand - Nematode parasites divert significant amounts of
photosynthate and nutrients to their feeding sites around the roots. This is made worse by reductions in the level of photosynthesis. This can occur shortly after the start of nematode feeding and represents a significant loss of energy for the plant.
2.Water Uptake - commonly we see changes in water uptake, stomatal conductance, root conductance and wilting. The water shortage results in a range of effects inside the plant including decomposition of proteins and nucleic acids, disruption of plant enzymes and decreases in nutrient uptake, solute movement and chloroplast activity.
3.Nutrient Uptake - abnormal morphology and root destruction results in the disruption of the flow of micronutrients and macronutrients.
4.Plant growth regulators - nematodes can also affect the levels and distribution of many growth regulators in the plant. For example, cytokinins (required for cell division, translocation and chlorophyll synthesis) and gibberelins (required for cell elongation) are produced in the roots. Root damage will disrupt their synthesis, so explaining the common
This photo shows a rootknot nematode in the eye of a needle
Subanguina root galls in the root system of a Poa plant
Chlorotic patches in a creeping bentgrass putting green caused by root knot nematodes
Abnormal root tip swelling caused by the needle nematode. This can seriously affect root function.
Pratylenchoides nematodes inside a creeping bentgrass plant root
Sheath nematodes are important pests in ryegrass soccer pitches
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