VG07070 Workshop Notes – 2008

This project was formed by Government agencies, private industry, universities and international researchers, to benchmark disease predictive models for major vegetable crops.

Three field trials were undertaken in 2008 to evaluate the new Brassicaspot model provided by HRI Warwick UK.

In all trials, the new model was compared with the old model using data obtained from the in-crop weather station and inputting the date of the appearance of white blister in the crop into the model program.


Liz Minchinton

Des Auer

Joanna Petkowski

VG07070 - Benchmarking predictive models, nutrients and irrigation for management of downy and powdery mildews and white blister - Workshop Nov 2008
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Progress report :

White Blister –  disease prediction :

  • At Werribee, no difference in incidence or severity between old, new or std. treatment, but the new model had significantly less severe symptoms than the unsprayed control.
  • At Rosebud, using the old model, sprays were reduced by 11 compared to the control
  • The old model was better than the new model in predicting when to spray to eliminate white blister from heads.

White Blister – irrigation timing :

  • Results for head incidence and severity mirror that observed on the foliage.
  • There was a higher incidence with those plants irrigated in the evening (8 p.m) as opposed to early morning (4 a.m).
  • There is some indication of white blister in heads of the tolerant cultivar Tyson, but again, severity in all cases, including Ironman was low.

White Blister – variety trials :

This trial evaluated six Broccoli varieties and two Cauliflower varieties for susceptibility to white blister.

  • Disease pressure from white blister has been low in this trial.
  • The ‘new’ broccoli variety and Tyson showed strong tolerance to white blister symptoms on heads.
  • Skywalker is more tolerant than Discovery, but white blister infection was very minor in cauliflower.
  • Plants had very dense foliage & many auxiliary shoots, providing an ideal microclimate for white blister. (the cultivar in question was Bridge
  • Standard sprays (9) produced the best control of white blister on foliage, but foliage is not marketed.

Downy mildew of Lettuce:

The aims of this module of VG07070 is to :

  • obtain a better understanding of the life cycle of the disease downy mildew
  • Apply knowledge to formulate a working model to use weatherstation data
  • Gather real-time data from weatherstations and assess the risk of downy mildew on lettuce crops through a working model.
  • Growth chamber studies are planned to refine downy mildew model.

Acknowledgments :

Funding was provided by Australian vegetable growers (through the R & D levy) and the Department of Primary Industries, Victoria. The Australian Government provides matched funding for all HAL’s R&D activities.

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