English names: Red Band Needle Blight, Dothistroma Blight
Nordic names: Rød nåleringplet (DK)
Estonian name: Punavöötaud
Major host plants
The principal hosts are Pinus spp. In rare cases, Pseudotsuga menziesii, Larix decidua and Picea abies growing right next to severely diseased pines have been reported to be infected. The most susceptible species of importance in the EPPO region are: P. canariensis, P. contorta, P. halepensis, P. muricata, P. nigra, P. pinea, P. ponderosa, P. radiata, P. sylvestris and P. thunbergii.
The most characteristic symptom of this disease is 1-3 mm wide brick-red bands that appear on the needles persisting after the needles have withered and turned brown. The end of the needle dies beyond the point of infection and the whole needle may develop extensive necrosis (browning) 2-3 weeks after the first appearance of symptoms. Diseased needles drop prematurely. Small, black fruiting bodies can be seen in the dead spots or bands on the needles. The first symptoms are found on needles of lower branches and the pathogen gradually moves up the crown. Successive years of severe disease and premature defoliation result in decreased growth and, in extreme cases, death of the tree.
M. pini is spread worldwide.
In Europe, the pathogen has been reported in Austria, Belgium, Bulgaria, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Italy, Lithuania, Netherlands, Poland, Portugal (Azores), Romania, Serbia, Slovakia, Slovenia, Spain, Switzerland, England, Wales, Scotland and Ukraine. A map can be downloaded from EPPO´s website. See instructions here.
Conidia (asexual fungal spores) are liberated from the stromata (fruiting bodies) in a film of water on the needle surface and are spread to susceptible hosts. The small black fruiting bodies erupt through the epidermis of needles infected in the previous year, and become visible during late spring to summer. Infection depends on many factors including period of needle wetness, temperature, and the quantity of spores available for infection. Infections occur within the temperature range 5-26°C. The age of the host also has a strong influence, and young trees tend to be more commonly attacked compared to older trees. Ascospores are also produced, but for a shorter period of time, and are considered to be less important as a source of inoculum compared to conidiospores.
Airborne conidia can be dispersed over short distances by rain splash; long distance dispersal by wind-dispersed moisture droplets, mist and low clouds. Longer distance dispersal can occur through infected needles which can become lodged in bark crevices and be transported with logs; movement of infected planting stock, and by seed mixed with small infected needle pieces.
Detection and inspection
Presence of a reddish tint in the necrotic needle tissue often visible as red coloured bands around the needle axis and the fruiting bodies. Laboratory examination is required for positive identification. If no reddening is visible, the macroscopic symptoms at the beginning of disease development can easily be confused with those due to Mycosphaerella dearnessii (Brown Spot Needle Blight) or Mycosphaerella gibsonii.
Pest status and importance
M. pini. is not listed as a quarantine pest for the EPPO region. However, it is listed under EU plant health legislation as a quarantine organism due to the rarity of the disease together with its potential to cause severe damage to certain species of pine. Where environmental conditions favour infection, this disease can spread rapidly and cause premature needle defoliation, poor growth and eventually leading to host tree mortality.
Source of information
See further information here:
Author:Eigil de Neergaard
Editor:Elise T. Yamamoto Buch