Alternaria leaf blight continues to pose a significant challenge for organic carrot producers. UC Cooperative Extension (UCCE) researchers have been trialing different materials for combatting disease pressures. The pathogen causes dark lesions on the leaves and petioles and can weaken the tops of carrots, ultimately impacting yield. UCCE Vegetable Crops Farm Advisor in Kern County, Jaspreet Sidhu said that two biofungicides are showing potential in their research.
“Howler, which is from AgBiome, and EcoSwing, which is from Gowan Company. These products looked promising in this trial and had lower disease pressure as compared to the control and other biological products,” Sidhu explained. “We had these weekly sprays starting at the onset of the disease and then a month before harvesting. We took the data on disease incidence and how the disease progressed over a period of time.”
Alternaria leaf blight is particularly troublesome for carrot growers because of the limited options of organic products with proven efficacy. A total of five biological products were part of the study conducted at the UC Research Farm in Shafter. Sidhu noted the statistical difference between the control plots and both Howler and EcoSwing was minimal. “But these products had lower numerical numbers than the controls and other the other products. Also, in terms of the yield, these two products have a little higher yield compared to the controls and the other products,” said Sidhu.
Based on the results of the biofungicides in last year’s trial, the research team will be conducting another trial this year. It will include both Howler and EcoSwing, along with other new chemistries. “We will see how consistent they are in their performance and if we could have some recommendations for the growers going into the future,” Sidhu explained.
Brian German
Ag News Director / AgNet West