Spectroscopy Research Challenges a Deadly Tree Fungus

Loblolly pine ranges from Georgia and the Carolinas to Texas but a destructive fungus is threatening this common southern softwood. Fusiform rust, Cronartium quercuum f.sp. fusiforme, is one the most destructive forest diseases in the South. With its complex life cycle, this fungus infects both loblolly and slash pine causing canker formation that frequently kills the infected branch.

The pine infection cycle occurs in Georgia in April and early May. Elongated swelling of the branches is the result of individual attacks on different parts of a tree. Many of the infected trees are unsuitable for later use as forest products, causing millions of dollars to be lost annually. Trees with large galls on the main stem are also unsuitable for many products.

Most of the photos in the above slideshow are by Robert L. Anderson, US Forest Service.

Changes in wood chemistry resulting from fungal decay of Scots pine have been studied directly using spectroscopy, the study of interactions between matter and radiated energy. A 2003 study by Pandey and Pitman exposed Scots pine sapwood to brown rot, selective white rot, and nonselective white rot fungi. In this study, the decay process was followed using Fourier Transform Infrared Spectroscopy (FTIR). After 12 weeks, the wood exposed to the brown rot fungus resulted in progressive increase in lignin content relative to cellulose and hemicellulose, whereas the lignin content of the wood exposed to the selective white rot decreased as decay proceeded. For the wood exposed to the nonselective white rot wood, both occurred.

A recently published FPL study applied both FTIR spectroscopy and Nuclear Magnetic Resonance Spectroscopy (NMR) to determine whether the pathogen caused any structural modifications to the chemical composition of lignin. A new FPL paper, Effect of Fusiform Rust (Cronartium quurcum f.sp. fusiforme) on the Composition of Loblolly Pine Lignin by Roderquita K. Moore, Allisha N. Blood, and Cherrelle I. Esekie discusses the results.