Fungal decomposition of attached angiosperm twigs

Abstract

SUMMARYInterspecific interactions between fungi frequently isolated (isolation frequency > 5%) from dead, attached a.sh twigs were studied on agar and in twigs at different water potentials in the lahoratory, and in twig lengths resuspended in the field. Under lahoratory and field conditions the following observations were made. The main primary colonizers of dead attached ash twigs, Plwmopsis plotanoidis Died., Fiisarium lateritium Nees. and Sp. 12, did not replace each other. Two of the common secondary colonizers, Libertellafraxinea Oganova and Acremonium sp. A, did not actively replace primary colonizers, except that L. fraxinea partially replaced P. platanoidis when associated with bacteria. The secondary colonizer Fetiiophora lycii (Pers,) v. Hohn & Litsch was, however, more combative and replaced all other species, provided tbat water potential was not lower than -4 MPa. There was some evidence that under field conditions P. lycii, arriving via the air spora could not replace P. platanoidis or Sp. 12; it apparently required a well established hase in the resource. However, it could replace F. lateritium and consequently gain a suitable foothold in twigs naturally colonized in the field. .Also, F. lycii demonstrated polar growth in twigs, progressively replacing other species.Active mechanisms by which fungi could resist replacement included the production of pseudosclerotial plates by F. platanoidis and the production of a volatile antifungal agent hy Sp. 12. There was also some evidence that other fungi, in particular F. lateritium, produced difl'usible antifungal substances, or altered growth conditions, which inhibited other fungi.

Fungi on stems and twigs in initial and advanced stages of dieback of European ash (Fraxinus excelsior) in Poland

“…It was not recorded in previous studies of ash twigs (Butin and Kowalski 1986;Griffith and Boddy 1988, 1991. Currently, it is found frequently on ash.…”

“…Similar results were reported from Sweden (Bakys et al 2009a, b). Most species that occurred commonly in this study have been found on stems and twigs of F. excelsior in various habitats (Butin and Kowalski 1986;Griffith and Boddy 1988, 1991Lygis et al 2005;Bakys et al 2009a;Chen 2012;Davydenko et al 2013).…”

“…Fusarium lateritium is also one of the main primary colonizers of the superficial tissues of living and dead ash twigs (Griffith and Boddy 1991). The high frequency of Fusarium species, particularly in symptomless ash tissues, may result from elimination of other fungal colonizers by production of antifungal metabolites (Riggenbach 1956;Griffith and Boddy 1991;Lysøe et al 2014). Studies on F. avenaceum and F. lateritium did not provide any evidence for their pathogenicity to F. excelsior (Bakys et al 2009a).…”

“…Colonization may result in the formation of smooth red-brown swellings on the stems, with small cracks at their margin (Janse 1981). Fusarium lateritium is also one of the main primary colonizers of the superficial tissues of living and dead ash twigs (Griffith and Boddy 1991). The high frequency of Fusarium species, particularly in symptomless ash tissues, may result from elimination of other fungal colonizers by production of antifungal metabolites (Riggenbach 1956;Griffith and Boddy 1991;Lysøe et al 2014).…”

“…and Phomopsis spp. are generally reported as the most common endophytes in ash bark and wood (Griffith and Boddy 1991;Kowalski and Kehr 1992;Sieber 2007;Bakys et al 2009a;Chen 2012). In symptomless branch bases, these three taxa were more frequent in F. excelsior than in ten other tree species examined (Kowalski and Kehr 1992).…”