Research and IPM
Models: Diseases
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Crop: Celery
Disease: Septoria Late Blight
Pathogen:
Septoria apiicola
Note: Before using a model that was not field tested or validated for a specific location, the model should be tested for one or more seasons under local conditions to verify that it will work in this location. See "Validation Work" below.
Model 1 of 3 |
Model developer and citation
Lacy, M. L. 1994. Influence of leaf wetness periods on infection of celery by Septoria apiicola and use in timing sprays for control. Plant Dis. 78:975-979.
Sensor location
Within crop row at a height of 0.3 m.
Input variables
Environmental: Leaf wetness duration.
Model description
The prediction of infection risk is based on twelve hours or longer of leaf wetness.
Action threshold
According to the model, initiate the first treatment after 12 or more hours of continuous leaf wetness. The timing of subsequent treatments is also based on 12 or more hours of leaf wetness, after a minimum of a seven-day spray interval.
Model validation
Lacy, M. L. 1994. Influence of leaf wetness periods on infection of celery by Septoria apiicola and use in timing sprays for control. Plant Dis. 78:975-979.
Model implementation
The model is still in validation phase.
Current limitations
The original model does not include temperature as an input variable, because temperature is not a limiting factor in disease development in Michigan, where the model was developed. However, temperature could possibly be a factor in other locations if temperatures below 10C or above 30C are experienced.
Related work
Mathieu, D. and A. C. Kushalappa. 1993. Effects of temperature and leaf wetness duration on the infection of celery by Septoria apiicola. Phytopathology 83:1036-1040.
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Model 2 of 3 |
Model developer and citation
Mathieu, D., and A. C. Kushalappa. 1993. Effects of temperature and leaf wetness duration on the infection of celery by Septoria apiicola. Phytopathology 83:1036-1040.
Sensor location
Not specified.
Input variables
Environmental: Air temperature, leaf wetness duration.
Model description
The model predicts the proportion of the maximum number of lesions (PML) as a function of duration of leaf wetness and temperature during wet periods. Disease severity values (DSVs) were then calculated from predicted PML values using cluster analysis. Accumulation of DSVs begins when celery transplants have recovered from transplant shock. After canopy closure, accumulation of DSVs ends, and the model reverts to a weekly application of treatments.
Action threshold
DSV action threshold has not been developed for this model. After canopy closure, the model reverts to a weekly application of treatments.
Model validation
Not known.
Model implementation
Not known.
Current limitations of model
This model needs to be validated in the field and action thresholds need to be determined.
Future directions of model
Development of a forecasting model to initiate fungicide applications; incorporation of interrupted leaf wetness and high relative humidity into the model.
Related work
Mudita I. W., and A. C. Kushalappa 1993. Ineffectiveness of the first fungicide application at different initial disease incidence levels to manage Septoria blight in celery. Phytopathology 77: 1081-1084.
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Model 3 of 3
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Model developer and citation
Modifications by Campbell Soup Company.
Pitblado, R. E. 1992. The development and implementation of TOM-CAST: A weather-timed fungicide spray program for field tomatoes. Ministry of Agriculture and Food, Ontario, Canada.
Madden L., Pennypacker, S. P., and McNab, A. A. 1978. FAST, a forecast system for Alternaria solani on tomato. Phytopathology 68:1354-1358.
Sensor location
Within canopy.
Input variables
Environmental: Air temperature, leaf wetness duration.
Calculated: Mean air temperature during the leaf wetness period.
Model description
Disease severity values (DSV) are calculated as a function of hours of leaf wetness and average air temperature during leaf wetness. The DSV is based on the FAST early blight model of tomato. After treatment the DSV accumulations reset to zero.
Action threshold
According to the model, initiate first treatment when 25 DSVs have accumulated. Subsequent treatments should occur each time 25 DSVs have accumulated.
Model validation
The model is being validated by Phil Phillips of the University of California, in Santa Barbara Co., Ventura Co., and by Campbell Soup Company in Sacramento Co.
Model implementation
Bolkan, H. A., and Reinert, W. R. 1994. Developing and implementing IPM strategies to assist farmers: an industry approach. Plant Dis. 78:545-550.