Senior Research Technician (Plant Protection) at the ARC Infruitec-Nietvoorbij



"I am working on identifying the diversity of fungal species causing
the dieback of honeybush."

Getting a hold on stem cankers

Fungal pathogen infections cause stem cankers. These stem cankers are recognised by the symptoms they cause, such as the dieback of plants. In my research, I focus on the specific plant pathogens related to these symptoms in honeybush. Environmental conditions play a significant role in the spread of fungal stem cankers. The symptoms can vary depending on the plant pathogen and infections, the growth stage and the age of the plant, a cultivar's resistance to stem cankers, and abnormal weather conditions. Canker pathogens survive from one year to the next in cankers on the plants, or on infected, pruned branches and twigs left in the tea plantation. Infections of healthy plants occur mainly through mechanical injuries, such as pruning wounds.

Why this matters

Stem cankers on honeybush plants are a serious problem as these plant pathogens cause serious dieback diseases of the plants and can be responsible for substantial losses in commercial plantations. Infection of healthy plants from stem canker pathogens occurs mainly through injuries with pruning wounds when unsterilised tools disseminate the spores from one plant to another as well as remove pruned branches and twigs with canker infection from the plantations. Currently, there is no control over these stem cancer pathogens and the diseases they cause. It is critical to carry out preventative measures where possible, and the first step is to identify which fungal species are the culprits. My research includes doing disease surveys, epidemiology (which deals with the occurrence, distribution, and control of diseases), genetic analysis, DNA identification, pathogenicity (the capacity of a microbe to cause damage in a host plant), and population studies of fungal pathogens affecting the honeybush industry

LOUISE_SMIT-small.jpgAbout the researcher

With almost 40 years' experience of scientific research into various plant species, including mushrooms, honeybush, rooibos, citrus and fruit, Smit is well qualified to handle the diagnostic identification of the fungal diseases that affect the honeybush plant. This work is considered an essential aspect of honeybush research. She has experience in studying stem cankers, fruit and root rot in deciduous fruit cultivars, as well as alternative crops such as honeybush, blueberries, cherries, grapevines, olives, pomegranates and raspberries. She currently leads the management of gene banks of microorganisms and DNA sequences for research and critical diagnostics at the ARC Infruitec-Nietvoorbij.


Louise Smit, a senior research technician at the ARC Infruitec-Nietvoorbij, is doing research on the plant pathogens responsible for stem cankers and other honeybush fungal infections.