Poster Presentation Science Protecting Plant Health 2017

The assessment of physiological methods for early, quantifiable stress and disease detection in banana plants  (#216)

Katelyn Ferro 1 , Carole Wright 2 , Joe El-Hayek 3 , David East 1 , Anthony Pattison 1
  1. Department of Agriculture and Fisheries, Queensland Government, South Johnstone, QLD, Australia
  2. Department of Agriculture and Fisheries, Queensland Government, Mareeba, QLD, Australia
  3. Department of Agriculture and Fisheries, Queensland Government, Moresby, QLD, Australia

Fusarium oxysporum f. sp. cubense Tropical Race 4 (TR4) was detected on a banana farm in north Queensland in March 2015, presenting a major risk to the viability of the $600 million Australian banana industry. Surveillance for infected plants continues through regular on-ground monitoring of external symptoms of TR4, which include lower leaf yellowing and pseudostem splitting. However, if detection of TR4 was possible before notable visual symptoms appeared, isolation and plant destruction could occur earlier to reduce the increase in inoculum and potential spread through soil movement.  Symptoms of TR4 infection can often be confused with those caused by other forms of stress, therefore reducing the ability to accurately identify suspicious plants. The aim of this study was to use rapid plant physiological assessment methods (proline accumulation in leaf tissue, chlorophyll fluorescence, chlorophyll content and thermal imaging) to elucidate the potential of effectively detecting and differentiating plant stress prior to the appearance of visual symptoms.  Furthermore, the severity of stress could be quantified offering objective measurements of leaf function. Stress treatments were applied to Cavendish banana ‘Williams’ (Musa AAA) plants in a glasshouse pot trial, which included: water logging; drought; nitrogen, potassium, and phosphorus deficiency; cold stress; and herbicide spray-drift. A 2 mM fusaric acid solution (a known toxin produced by TR4) and a control treatment were also included. Over the three month experiment the physiological tools could not differentiate between the control and stress treatments before visible symptoms were detectable and require further refinement for future work in early disease detection. However, the tools gave quantifiable measurement of the severity of stress by the loss of leaf function and provided alternatives to subjective disease assessments of bananas.