Preliminary assessment of control options for powdery mildew and two spotted mite in field grown fresh tomatoes (VT06000)

This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

Powdery mildew species Leveillula taurica and Oidium lycopersici had become a significant problem for field grown tomato growers in the Goulburn Valley. Control was multi faceted with both fungicide and cultural practices being of equal importance. As a result of the increasing pressure powdery mildew was placing upon the production of tomatoes, the evaluation of fungicides registered for tomatoes and alternative chemistry registered on other crops was a priority.

The trial work conducted in season 2006-07 evaluated the efficacy of five fungicides, three existing products commonly in use for the control of powdery mildew and two unregistered products. The treatments and an untreated control were visually assessed at various growth stages and the rate of infection on each occasion was recorded. This information was then used to apply statistical analysis, to determine if the use of alternative products had produced a significant reduction in the infection rate of powdery mildew. In addition, leaves from plants in each treatment plot were harvested, collated and assessed according to the severity of infection. Fruit from the two unregistered product treatments were also subjected to chemical residual testing.

Season 2008-09 provided an opportunity to follow up on previous work, with an aim of encouraging growers to test a best practice approach to the control of powdery mildew in comparison to their standard program. The key management areas that differed between the two programs included; the incorporation of new fungicides, improvement of soil health through strategic applications of organic products and the balancing of plant nutrition. Assessments on the rate of infection in the treated and untreated comparisons were conducted as in the previous trial, as well as evaluating yield improvements.