36th International Carrot Conference Abstract

The development of a web-based tool for carrot disease forecasting

Kenneth E. Frost¹, Russell L. Groves², and Amanda Gevens³

¹Research Associate, Department of Plant Pathology, 574 Russell Laboratories, University of Wisconsin, Madison, WI 53706 kfrost@wisc.edu (608) 262 – 9914; ²Associate Professor and Entomology Extension Specialist, Department of Entomology, 537 Russell Laboratories, University of Wisconsin, Madison, WI 53706 groves@entomology.wisc.edu (608) 262 – 3229; ³Assistant Professor, Department of Plant Pathology, 689 Russell Laboratories, University of Wisconsin, Madison, WI 53706 gevens@wisc.edu (608) 890 – 3072.

Alternaria leaf blight, caused by the fungus Alternaria dauci, and Cercospora leaf spot, caused by the fungus Cercospora carotae, infect leaves and petioles of carrot and are the most prevalent foliar diseases of carrot worldwide. These foliar blight pathogens reduce yield by limiting the plant’s photosynthetic capacity and by weakening the petioles needed for mechanical harvest. Typically, carrots are harvested by implements that loosen the soil and simultaneously grasp the foliage while lifting the roots out of the soil; blighted petioles break when gripped by the mechanical harvester and carrots are left in the soil. Environmental conditions greatly influence the occurrence and progression of these foliar diseases of carrot and the anticipation of heightened disease risk through the identification and monitoring of critical environmental factors, such as, relative humidity and temperature, can enhance disease management by optimizing the timing of fungicide applications. However, implementation of the weather-based models is difficult because, typically, each field requires a customized forecast that is dependent on disease severity, weather conditions, and fungicide program, factors that are field-specific. A goal of this research is to provide a set of generalized recommendations for managing foliar diseases of carrot that can be used for the majority of WI fields without the need for grower investment in weather stations. In 2013, a modified TOM-CAST disease forecasting model for carrot foliar disease is being evaluated in field trials for the management of A. dauci and C. carotae, respectively. This model uses environmental variables, from in-field weather stations and gridded weather predictions from the North American Meso-scale (NAM) weather model, to calculate an action threshold for fungicide applications. Research plots are being established at the UW-Hancock Agricultural Research Station and on a commercial farm with four replicates. Plots will be scouted for disease weekly from mid-June to early September and all treatments will contain a standard fungicide program. Additional treatments will be established to examine when a fungicide program should be initiated for optimal control of carrot foliar diseases with treatment applications being initiated based on both disease symptoms and historical weather and disease incidence data. The development of an internet-based graphical user interface to automate the functionality of the database and make these disease forecasts available to vegetable growers in WI, currently underway, will be discussed.

Last updated Thursday, 25-Jul-2013 11:54:41 CDT