The pine nematode: damage, symptoms and preventions

The pine nematode,  Bursaphelenchus xylophilus, is a worm less than 1 mm in length that inhabits coniferous wood (not only pine trees are affected). In Gardenprue we are going to know in detail how this nematode works, the problems it is causing and the control methods.


It is without a doubt the most dangerous organism for conifers worldwide. The pine nematode causes pine drought or sudden pine decay (Pine Wilt Disease). The symptoms are generic and can be confused with other pests or diseases (insects or fungi) or even problems related to cultivation tasks (stress or drought). The pine nematode disease that ends with the death of the tree only occurs when primary transmission occurs and also the climatic and environmental conditions (temperature and water deficit) are high. That is, for the damage to the conifer to be irreparable apart from the nematode attack , the tree must be weakened.


Trees that were fully healthy at the beginning of summer, die in early October (end of summer) with a reddish-brown coloring of their foliage. The needles turn yellow and end up wilting. This wilting is due to a reduction in perspiration. At the onset of the disease there is a drastic reduction in gum or resin exudates. Two weeks after the onset of the disease, the exudates are reduced, and from the third week the exudates are completely paralyzed.

With all these antecedents the tree faints and dies between 30 and 40 days after the onset of the disease, provided that the thermal conditions of the environment are favorable. In Japan, for example, given the climatic conditions of the environment, the pine nematode takes between 1 year or 1 year and a half to kill a pine tree, so temperature has an important influence on the development of the disease. High temperatures and water deficit increase the conifer’s susceptibility to attack by the pine nematode.


Bursaphelenchus xylophilus  is propagated by means of a vector. This host organism is the  Monochamus galloprovincialis,  known as the longicorn of the pine, it is a waxen beetle that feeds on the young shoots of the pines, so the transmission of the nematode in the conifers is simple.

Life cycle of the pine nematode.
Source: How to Identify and Manage Pine Wilt Disease and Treat Wood Products Infested by the
Pinewood Nematode, USDA, NA-FR-01-04

This pest travels very little and does not travel more than a radius of 3 km throughout its biological cycle. The only way to explain the progression of the disease, worldwide, is based on the international marketing of coniferous wood.



In the case of pines, the species most susceptible to the pathogen, such as Pinus nigra, P.pinaster   and P. sylvestris , should be carefully evaluated  


The species susceptible to the pine nematode must have a phytosanitary passport that guarantees the safety of the pathogen in the wood, through a heat treatment of 56º C for 30 min.


By this method the biological burden of the vector of the genus Monochamus is reduced .


By cutting down trees that are decaying or affected by the pine nematode, the spread of the disease is prevented through the vector. It is a measure that is being carried out in all affected areas.


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