Managing powdery mildew in cucurbits to prevent crop losses
The study aimed to find new ways to control powdery mildew in cucumber and zucchini crops to prevent crop and income losses. It used integrated pest management and safe chemicals (rather than problematic synthetic fungicides) that boost the plant’s natural defence systems. Systemic acquired resistance could allow growers to minimise the number of chemical applications in a season, without compromising crop yield.
Why study this?
Powdery mildew causes significant crop losses of greenhouse and field-grown cucurbits in Australia. The disease is currently controlled using synthetic fungicides. There are many problems associated with the use of these, eg an increase in pathogen resistance, community concern for threats to human health, and unpredictable economic or environmental consequences of their use.
What was done
The strategy investigated incorporated integrated pest management and safe chemicals that boost the plant’s natural defence systems. These chemicals induce systemic acquired resistance (SAR) in plants so that they are ready to fight a pathogen when it attacks.The efficacy of Bion®, Milsana® and Rezist®, along with conventional fungicides, was evaluated for the control of powdery mildew of cucumber and zucchini. All the chemicals significantly reduced powdery mildew under glasshouse and field conditions.
What we found
Results showed that disease control using this method was excellent for cucumbers, not as dramatic for zucchini. Also that good agronomic practices were critical, with healthy plants responding much better than those compromised by lack of water or nutrients etc.
Where to next?
As of 2004, many chemicals used in these trials are not registered for use on horticultural crops in Australia. It may be possible to apply for minor use permits for Bion®, Rezist® and Milsana®. If more Australian efficacy data is collected then the case for registration may be able to be put to APVMA.
Because it is possible to control powdery mildew using this method, more Australian efficacy data should be collected to enable a case to be made for registration of the chemicals used most successfully.
Resources
Managing mildews using SAR in cucurbits
For more information contact
Dr Gordon Rogers, Applied Horticultural Research Pty Ltd
VG05034