Phytopathogenic Fungus Fusarium circinatum and Potential for Its Transmission in Russia by Insects

Аннотация

The emergence of the ascomycete Fusarium circinatum Nirenberg & O’Donnell (teleomorph Gibberella circinata), the causal agent of pitch canker of pine in Europe, is an alarming signal to Russia. This review briefly summarizes the analyses of biology of F. circinatum and its vectors of dissemination. Open wounds on the bark of the trunk and branches can be the gates for the droplet and airborne infection caused by the Fusarium phytopathogens. The infection is followed by the formation of cankers caused by the related phytopathogens, the occurrence of severe resin bleeding, and the death of the crown. In Russia, this pathogen can emerge and spread in the Black Sea coastal area (most likely toward the southeast of Krasnodar) in pine nurseries and plantations. However, it is not clear yet whether the regional climate conditions will be optimal for F. circinatum and how competitive it will be in new environments. The insect species associated with the pine trees are considered as an important factor for dissemination of F. circinatum, since they can be both the direct carriers of the fungal propagules (i.e., act as the vectors for transmitting the causal agents) and the cause of the physical damage to the pine shoots, branches, and trunk, becoming a gates for infection. After completing the life cycle on the tree infected with F. circinatum, the mature insect migrates to another possibly healthy tree, carrying the sticky fungal spores adhering to the surface of its body and leaving them attached to the new host tree. The study describes the insect species associated with the pines (Pinus). In addition, it is concerned with analyzing their role in dissemination of F. circinatum. It has been proved that, in Russia, there are many insects potentially capable of rapidly spreading the pitch canker of pines if F. circinatum invades the country.