Significant achievements have been made in the identification of fungal phytopathogens associated with grey-brown stinkbug specimens occurring in pecan orchards.

The main aim of the study was to confirm the role of stinkbugs in the dissemination of fungal pathogens in pecan orchards. In addition, the pathogenicity of Alternaria tenuissima, Cladosporium cladosporioides and Neofusicoccum parvum. was confirmed. The effect of wounding vs. non-wounding on disease development was also compared. The pathogenicity of the three fungal isolates was determined with trials conducted under both laboratory and greenhouse conditions.

Results showed that both A. tenuissima and N. parvum associated with the grey-brown stinkbug are pathogenic on pecans. This is the first report that N. parvum is a pathogen of pecans. Cladosporium cladosporioides was unable to cause any disease symptoms of note. Wounding greatly increased the onset of disease development and as a result the severity. From the results it can be concluded that the grey-brown stinkbug is associated with pathogens of pecans.

These stinkbugs most likely play a role in the spread of these pathogens within orchards and assist with infection by providing entry points via. feeding damage. In addition 65 fungal isolates found during previous research have been identified with molecular techniques.

The research focuses on the interactions and relationships between insects and fungi occurring in tree nut crop orchards (pecan, pistachio and walnuts) in semi-arid regions of South Africa. Research on insect-fungal associations may lead to better management of both fungal phytopathogens and/or pest insects.

Understanding insect-fungal interactions, might be essential in the development of proactive measures to reduce the spread and occurrence of diseases, and may possibly be used as an indicator for the incidence and risk posed by phytopathogenic fungi.

Congress presentations:
Saaiman, J., Swart, V. R. & Marais, G. J. 2013. Fungi associated with the powdery stinkbug in pecan orchards in South Africa. 48th Congress of the Southern African Society for Plant Pathology. ATKV Klein Kariba, Bela Bela, South Africa, January 2013.
Saaiman, J., Swart, V. R. & Marais, G. J. 2013. The interaction between stinkbugs and fungi in pecan orchards in South Africa. 18th Congress of the Entomological Society of Southern Africa (ESSA). North-West University, Potchefstroom, South Africa, July 2013.