TPCPbanner2.jpg

Damage

Tree disease and death can arise from a multitude of factors, including living organisms (biotic) such as insects and fungi, or abiotic agents such as frost, drought and chemical damage. In order to adjust management practices appropriately, it is crucial to correctly identify the cause of damage to trees. The following section summarizes some of the most common causes of tree damage or disease and provides guidelines for distinguishing between the different categories of damage, disease and decline.

Distinguishing between causes of tree health problems

Abiotic Biotic
Non-living (eg. chemicals, frost, drought) Living (Fungi, bacteria, insects)
Absence of host specificity Often host specific
Non-infectious Infectious (can spread from one tree to another)
Usually a gradient visible (worst near source of origin, with impact gradually becoming less as distance from source increases)
Damage usually of same age/phase of expression
Often random in the plantation
Damage often at different stages of development as pathogen/pest spread from one tree to another

Signs and Symptoms

Disease and pest problems may be identified by observing certain signs and symptoms of infection / infestation. Signs include the presence of fungal fruiting bodies, or egg capsules of insects, while symptoms include leaf spots, defoliation, cracking of stems, wood stain etc. Characterizing the type of damage and the visible signs is useful in making accurate diagnoses.

New Publications

Export to RIS
Human ZR, Crous CJ, Roets F, Venter SN, Wingfield MJ, de Beer ZW. (2017) Biodiversity and ecology of flower-associated actinomycetes in different flowering stages of Protea repens. Antonie van Leeuwenhoek 10.1007/s10482-017-0942-3
Wingfield BD. (2017) The peer review system has flaws. But it’s still a barrier to bad science. The Conversation http://bit.ly/2holsgS
McTaggart AR, Beasley DR, Wingfield MJ, Wood AR, Pretorius ZA, Drenth A, Shivas RG, Roux J. (2017) A dynamic, web-based resource to identify rust fungi (Pucciniales) in southern Africa. MycoKeys 26:77-83. 10.3897/mycokeys.26.14602
De Maayer P, Aliyu H, Vikram S, Blom J, Duffy B, Cowan DA, Smits THM, Venter SN, Coutinho TA. (2017) Phylogenomic, pan-genomic, pathogenomic and evolutionary genomic insights into the agronomically relevant enterobacteria Pantoea ananatis and Pantoea stewartii. Frontiers in Microbiology 8(1755) 10.3389/fmicb.2017.01755
Jami F, Wingfield MJ, Gryzenhout M, Slippers B. (2017) Diversity of tree-infecting Botryosphaeriales on native and non-native trees in South Africa and Namibia. Australasian Plant Pathology 10.1007/s13313-017-0516-x