Septoria apiicola model

This model is based on a calculation of how leaf wetness periods influence infection of celery by Septoria apiicola in susceptible host plants.

Forecasts of infection risk are given after a minimum of 12 consecutive hours of leaf wetness. The wet periods are calculated from sensors placed 30 cm above ground. If such a sensor is not available, data from leaf wetness sensors placed 2 m above ground are used.

The model is developed in Michigan, USA and published by Lacy, 1994.

It is generally assumed that this model has additional relevance for Septoria petroselini in parsley.

Warning interpretation

The following recommendations are provided for the Norwegian celery production.

The model is a tool to decide when to start looking for initial disease outbreaks. It is not considered accurate enough to provide reliable advice for timing of fungicide applications under Norwegian conditions.

If inoculum is present, infections are expected to develop 7-14 days after the first infection risk periods (yellow or red warnings). It is recommended to intensify field inspections after periods with risk warnings to detect early infections of Septoria apiicola.

• Green: No risk of infection.
• Yellow: Weather conditions favorable for infection risk. No known sources of inoculum in the region.
• Red: Risk of infection and infections of Septoria late blight has been reported in the nearby region. Disease reports and field inspections are performed in collaboration with advisors in the Norwegian Agricultural Advisory service.

Graph legend: Blue bars indicate periods of at least 12 consecutive hours of leaf wetness. Black bar indicate date of first field observation of Septoria late blight.

Forecast season (Norway only)

In Norway this model is generally started June 1 and ends September 30.

The model is running on all weather stations located in regions of commercial celery production.

Model validation

Norway

Validation of this model under Norwegian conditions is ongoing. The current recommendation for this model is as a tool for timing of field inspections.

Studies of weather conditions, spore production and infection events have been carried out in field trials at Ås from 2012-2016. Preliminary results indicate a good fit, although some adjustments could improve the model, particularly in connection with rain events (Nordskog and Le, 2014).

Internationally

The model is developed in Michigan, USA and published by Lacy (1994)

References

Lacy, M.L. 1994. Influence of wetness periods on infection of celery by Septoria apiicola and use in timing sprays for control. Plant Disease 78, 975-979.

Nordskog, B. og Le, V.H. 2015. Varsling av selleribladflekk. Gartneryrket nr 6, s14-15.

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		"endDateCalculation":"2012-03-25",
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