Systemic induced resistance to control root and foliar diseases of urban trees

2005 | Dr. Glynn Percival
Investigate the efficacy of a range of commercially available SIR compounds on apple scab and Phytophthora root rot.

Study Results

A range of laboratory based detached leaf experiments in combination with several containerized pot and field trials were conducted over a four year period to evaluate several systemic inducing resistance (SIR) agents on disease severity of apple (Venturia inaequalis) pear (V. pirina), powdery mildew (Microsphaera alphitoides) three foliar biotrophic pathogens and Phytophthora root rot, a root invasive pathogen. Tree species used in these studies included English oak (Quercus robur), horse chestnut (Aesculus hippocastanum), apple (Malus cvs. Golden Delicious and Floribunda) and pear (Pyrus communis ‘Williams’ Bon Chrétien’). SIR products tested included Messenger (herapin protein), Phoenix (potassium phosphate), Asprin (salicylic acid) Rigel (Salicylic acid derivative), Bion (Benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester) and BABA (DL-β-amino-n-butyric acid).

All SIR agents used inhibited germination of fungal conidia, subsequent formation of appressoria and reduced leaf disease severity using a detached leaf bioassay. Containerized pot and field trials demonstrated that disease severity of all foliar pathogens tested could also be reduced by, on average, 60% following application of an appropriate SIR agent provided at least three spray applications were applied during the growing season. Throughout all experiments, however, the synthetic fungicides myclobutanil and penconazole used for comparative analysis resulted in the greatest levels of germination inhibition, reduced appressorium development and leaf disease severity. Experiments using Phytophthora root rot produced similar results in that root rot severity could be reduced by on average 62% following application of an appropriate SIR agent. However, a comparative evaluation of the fungicide Aliette 80 WG (fosetyl-aluminium) commercially used for Phytophthora root rot control provided the greatest degree of control. Results suggest application of an appropriate SIR product may provide a useful addition to existing methods of foliar and root disease management provided total control was not warranted.

Year: 2005

Funding Duration: 3-5 years

Grant Program: Hyland R. Johns

Grant Title: Systemic induced resistance to control root and foliar diseases of urban trees

Researcher: Glynn Percival

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