Poster Presentation Science Protecting Plant Health 2017

Managing damping off in baby-leaf spinach in Australia (#344)

Len Tesoriero 1 , L Spohr 1 , A Harris 1 , D Luca 2 , D Blaesing 2 , K Montagu 3 , G Rogers 3
  1. NSW Department of Primary Industries, Ourimbah, NSW 2258, Australia
  2. RM Consulting Group, Camberwell, Victoria 3124, Australia
  3. Applied Horticultural Research Ltd ATP, Everleigh, NSW 2015, Australia

Baby-leaf spinach production in Australia has surged in recent years. It is currently valued at $55M annually. Year-round supply of semi-processed product requires a network of growers spanning all states except the Northern Territory. Damping off has become a significant constraint in this intensive production system where multiple crops are often grown without rotation. Diseased plants have yellow or wilted leaves which contaminate the harvested marketable product. Furthermore when plants are damped off the remaining healthy plants have a flatter habit making machine harvesting more difficult and causing many leaf blades to be cut rather than at the petiole. This leads to a reduced shelf life and sometimes rejection by the processor. This study has identified the pathogens causing damping off in different production areas and we have commenced field trials to evaluate a number of chemical, cultural and biological control options. The key pathogens determined so far are various species of Pythium, namely P. aphanidermatum, P. ultimum var ultimum and P. irregulare; Rhizoctonia solani; and Fusarium oxysporum f.sp. spinaciae. They appear to have both temporal and spatial differences in their occurrence and importance. A field trial in Richmond, Tasmania over the past summer compared drench treatments at sowing of metalaxyl-M, azoxystrobin, propamocarb, fosetyl-Al, and a commercially formulated strain of Bacillus subtilis. A combination of metalaxyl-M and azoxystrobin and another treatment with a combination of propamocarb, fosetyl-Al and B. subtilis resulted in significantly fewer diseased plants although yield differences were not significant. Both Rhizoctonia and Pythium ultimum were confirmed as the key causes of the diseased plants. Further studies are planned with chemically dressed seed and biocontrol treatments as well as assessments of the ameliorative effects of different cover crops and biofumigants.