Powdery mildew caused serious problems for many horticultural crops at the time, especially when it covered the leaves of the plant and as a result the plant didn’t produce fruit which meant a reduced return for the grower.

This project aimed to search for new ways to control powdery mildew in cucumber and zucchini crops. The strategy investigated incorporated integrated pest management and safe chemicals that boosted the plant’s natural defence systems. These chemicals induced systemic acquired resistance (SAR) in plants so that they were ready to fight a pathogen when it attacked. Systemic acquired resistance allowed growers to minimise the number of chemical applications in a season, without compromising crop yield.

The results showed that the disease control using this method was excellent for cucumbers. However the response was not as dramatic for zucchini. The results also showed that good agronomic practices were critical with healthy plants responding much better to the program than those that were compromised by such things as lack of water or nutrients.

At the time, many of the chemicals used in these trials were not registered for use on horticultural crops in Australia. However, it may have been possible to apply for minor use permits for these chemicals (Bion®, Rezist® and Milsana®) to allow this work to continue. If more Australian efficacy data was collected then the case for registration may have been able to put to APVMA in the future.

This project has been funded by Hort Innovation, using the research and development levies listed below and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.

• Vegetable Fund