Viticulture and Grapevine Declines : Lessons of Black Goo

Abstract

Diseases that cause the premature decline and death of grapevines are a threat to the economic viability of vineyards everywhere. Although research has brought about major progress in the understanding of grapevine viral diseases, the same progress has not occurred with fungal diseases which can be equally devastating to the expected life span of vineyards. The role of pathogenic fungi in grapevine declines may be overlooked because of misattribution to other causes. For example, decline in grafted vines where the rootstocks are infected with species of Phaeoacremonium and/or Cylindrocarpon may be attributed to cultural practices or site conditions. Therefore, growers unknowingly plant (and replant) new vineyards with diseased material from nurseries who are unwittingly selling infected plants. Clearly, there can be no solution for a problem that remains unrecognized. Today, there is an urgent need for research into the significance of the spread of disease by Phaeoacremonium spp.-infected mother vineyards, particularly in American Vitis rootstock varieties. The economic hardship posed by these fungi extends beyond the grower to the nursery industry as well. Even those nursery suppliers who are aware of the potential presence of Phaeoacremonium spp. in their plant material do not know exactly what steps to take to eliminate it. Founded in 1998, the International Council on Grapevine Trunk Diseases (ICGTD) can work to improve communication among those studying the same diseases by developing common terminology and data collection protocols, as well as coordinating research projects to avoid redundancies. This multi-disciplinary approach will hasten progress in understanding the significance of pathogenic fungi in propagation material, as well as finding methods of controlling disease expression in infected vineyards. Using the case of black goo caused by P. chlamydosporum, both the symptom and disease expression, I offer here my outlook on issues related to the study of grapevine declines.