Incidence of gummosis disease in silky hakea under natural conditions in South Africa

The pathogen Colletotrichum acutatum J.H.Simmonds was developed in South Africa during the 1980s as a mycoherbicide to control invasive silky hakea (Hakea sericea Schrad. & J.C.Wendl.) and subsequently widely used by variety of land managers induce gummosis disease. To determine persistence under natural conditions, disease incidence severity were monitored annually at five sites Western Cape Eastern provinces, from 2008 until 2017. Disease ranged between 12% 95% trees with first year. At four sites, high levels mortality recorded years monitoring. In year highest mortality, 38 64% dead. No fifth site. reduced latter years, coinciding drier conditions. three fires occurred once course monitoring reappeared one post-fire. It concluded that although will persist for maximum benefit fungus should be actively applied maintain mortality. Depending on site characteristics weather trends, this an annual, bi- or triennial basis, following dry years.