Last summer a pepper differential trial was done near Vineland, NJ to help determine if new races of bacterial leaf spot (BLS) were present in the area. At least 11 races of BLS have been identified to date.
…look at ways to detect the presence of BLS susceptibility on your farm. Run your own internal “tests”: plant a few cultivars with known BLS resistance and take note which ones develop symptoms. Be ready to adopt cultivars with a larger BLS resistance package.
Why is race identification important? Remember, the genes for resistance in bell pepper determine which cultivars are susceptible to and which ones are resistant to the bacterial leaf spot pathogen. Long ago, bell pepper growers in New Jersey could rely on those cultivars which carried resistance to BLS Races 1, 2, and 3. In the last few years, those cultivars with BLS 1-3 resistance started developing symptoms, and subsequently, Races 4 and 5 were detected in the state. This past year, BLS Race 6 was detected near Vineland.
What does this mean for NJ Growers? First, it tells us that bacterial leaf spot populations are diverse and always evolving. Growers now need to begin to take into consideration that up to 6 races of BLS may be present (on their farm) and should begin to look at ways to detect and help mitigate potential problems. If you have been growing specific cultivars, for example, with resistance to BLS Races 1-3, and you are seeing BLS develop in your fields, it’s a sure sign that you have BLS Races 4, 5, and/or 6 present on your farm. Importantly, take notes and run your own internal “tests” on a regular basis. For example, if you are growing Declaration or Revolution and BLS symptoms develop, there is a good chance Race 4 or 6 is present on your farm. Simply plant a few cultivars with known BLS resistance and take note which ones develop symptoms. See Table below and updated pepper Variety list on page F108 of the 2014 Commercial Recommendations Guide.
Importantly, be ready to adopt cultivars with a larger BLS resistance package if necessary. Many of the newer cultivars now carry larger BLS resistance packages and some also have Phytophthora-tolerance. Both 1819 and Tom-Cat have resistance to BLS Races 1-5, 1819 also has some Phytophthora-tolerance where Tom-Cat is susceptible. Unfortunately, cultivars such as Paladin with excellent Phytophthora-resistance lack BLS resistance.
|Cultivar||BLS race resistance||Phytophthora Resistance|
R = Phytophthora-resistant; T = Phytophthora-tolerant; none = susceptible