Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2006
Publication Date: 5/23/2007
Citation: Gugino, B.K., Carroll, J.E., Widmer, T.L., Chen, P., Abawi, G.S. 2007. Field evaluation of carrot cultivars for susceptibility to fungal leaf blight diseases in new york. Crop Protection 26:709-714
Interpretive Summary: Fungal leaf blight disease of carrots caused by two fungi is an annual problem in New York. Carrot cultivars react differently in their susceptibility to these diseases. The objective of this study was to evaluate commonly grown carrot cultivars in New York for their disease reaction so that this could be used in an integrated pest management program. It was found that five different carrot cultivars were resistant to one fungus while three were resistant to the other fungus. Two of these cultivars were the same for both fungi. One of the cultivars was the most susceptible for both fungi. The results presented are important in that they provide information to the grower on what carrot cultivars are most likely to get diseased. This information can then be used to better predict the amount of fungicide applications that will need to be used.
Technical Abstract: Carrot cultivars grown in New York were evaluated for susceptibility to the fungal leaf blight pathogens Alternaria dauci (1999) and Cercospora carotae (2000 to 2003)in an experimental field under continuous carrot cultivation since 1996. Replicated plots were established in a randomized complete block design. Plants were rated for disease incidence and severity at regular intervals. Cultivar susceptibility was ranked based on the area under the disease progress curve. An IPM program for carrot leaf blights conducted in growers’ fields provided the opportunity to determine the impact susceptibility had on date fungicide threshold was reached. Bolero, Carson, Calgary, Ithaca, and Fullback were resistant to Alternaria. Bolero, Carson, and Bergen were resistant to Cercospora. Fontana was most susceptible to both leaf blights. In grower fields, more resistant cultivars reached the 25% disease incidence threshold later than more susceptible counterparts. Carrot cultivar susceptibility was incorporated into an IPM program for these diseases.