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

Jami F , Marincowitz S, Slippers B, Wingfield MJ. (2018) New Botryosphaeriales on native red milkwood (Mimusops caffra). Australasian Plant Pathology 10.1007/s13313-018-0586-4 PDF
Estrada-de los Santos P, Palmer M, Chávez-Ramírez B, Beukes C, Steenkamp ET, Briscoe L, Khan N, Maluk M, Lafos M, Humm E, Arrabit M, Crook M, Gross E, Simon MF, Bueno dos Reis F, Whitman WB, Shapiro N, Poole PS, Hirsch AM, Venter SN, James EK. (2018) Whole Genome Analyses Suggests that Burkholderia sensu lato Contains Two Additional Novel Genera (Mycetohabitans gen. nov., and Trinickia gen. nov.): Implications for the Evolution of Diazotrophy and Nodulation in the Burkholderiaceae. Genes 9(8):389. 10.3390/genes9080389
Naalden D, Haegeman A, de Almeida‐Engler J, Eshetu FB, Bauters L, Gheysen G. (2018) The Meloidogyne graminicola effector Mg16820 is secreted in the apoplast and cytoplasm to suppress plant host defense responses. Molecular plant pathology 10.1111/mpp.12719https://onlinelibrary.wiley.com/doi/abs/10.1111/mpp.12719
Marin-Felix Y, Hernandez-Restrepo M, Wingfield M, Akulov A, Carnegie A, Cheewangkoon R, Gramaje D, Groenewald J, Guarnaccia V, Halleen F, Lombard L, Luangsaard J, Marincowitz S, Moslemi A, Mostert L, Quaedvlieg W, Schumacher R, Spies C, Thangavel R, Taylor P, Wilson A, Wingfield B, Wood A, Crous P. (2018) Genera of phytopathogenic fungi: GOPHY 2. STUDIES IN MYCOLOGY 92:47 - 133. 10.1016/j.simyco.2018.04.002
Burgess TI, Tan YP, Garnas J, Edwards J, Scarlett KA, Shuttleworth LA, Daniel R, Dann EK, Parkinson LE, Dinh Q, Shivas RG, Jami F. (2018) Current status of the Botryosphaeriaceae in Australia. Australasian Plant Pathology 10.1007/s13313-018-0577-5 PDF