Unraveling the Mystery: Decades-old Pine Tree Disease Solved with DNA Technology

In the era between the 1970s and 1980s, forestry plantations in the Western Cape of South Africa witnessed an ominous phenonmenon - pine trees began showing symptoms of a mysterious root disease leading to their gradual and unrelenting demise. Indigenous seedlings once flourishing spontaneously in these afflicted patches also began to die on a massive scale. As the patches grew, this drama witnessed its first suspect, the root-infecting Phytophthora cinnamomi, known as the 'plant destroyer'.

As investigations deepened, tree pathologists came across the fungus Leptographium serpens (now identified as Leptographium alacre). Prior to this discovery, this fungi was known to exist only in Europe and was identified visually from the roots of the dying pines, making it the prime suspect. However, doubts lingered.

Jump to 2023, a promising perspective presented itself in the form of DNA sequencing. This modern technology managed to decode the enigma that stumped scientists in the yesteryears. The long-held suspect, L. serpens, was replaced by the true perpetrator, Rhizina undulata or locally known as the ‘coffee fire fungus’.

Rhizina undulata is a notorious cause of tree disease and death principally in Europe. Its spores become active with intense heat, such as a forest fire, leading to an invasion of conifer roots. This fungus is a familiar foe in South Africa, particularly devastating post forest fires or tree felling plantation clearings.

The trigger behind the fungus activation in the Western Cape remains elusive as no fires were recorded during the relevant period. Scientists are considering possible causes like the acidic nature of the Table Mountain sandstone soil or heat from common quartz rocks available in the affected regions.

The findings are not just a step forward in controlling the future spread of this fungus but also a testament to the importance of technological advancement in scientific research and extensive preservation of diverse fungal cultures.