Increasing frequencies of diamondback moth issues in cole crops highlights the importance of an integrated pest management (IPM) approach. Many growers in California and Arizona have been reporting difficulty in managing the pest in cruciferous crops. Cooperative Extension Advisor for Entomology and Biologicals Surendra Dara said producers have been noticing an increased problem with management for about a year now.
“The problem primarily seems to be that the pesticides they use are not working well,” Dara explained. “That is usually because of insecticide resistance issues which results from repeated use of certain active ingredients or insecticides from certain mode of action groups.”
In a recent article, Dara points out that year-round production of cruciferous crops lends itself to continuous development of diamondback moth populations. As many as 12 generations can populate in a year, requiring regular pesticide applications. The increasing prevalence of infestations are necessitating more frequent treatment, which increases the potential for further insecticide resistance.
“This seems to be a bigger problem in some areas than others,” Dara noted. “It is in the Oxnard area and some regions in the Central San Joaquin Valley that we are seeing problems with resistance or higher infestations.”
Management tools for diamondback moth have remained largely the same in recent years. Dara points out that one new tool available to producers is a sprayable pheromone for mating disruption. Other critical components of an IPM strategy includes product rotation, host plant resistance, cultural and biological controls, as well as physical control. An integrated approach will be crucial for combatting further resistance in diamondback moth populations and help ensure adequate control moving forward.
“The key point there is to understand what is happening and what kind of resistance growers might be seeing and maximizing the potential of non-chemical alternatives,” said Dara. “No single tool provides complete control, but we have to take advantage of each and every one.”
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