Effect of neonicotinoid, pyrethroid and spirotetramat insecticides and a miticide on incidence and severity of Yellow Canopy Syndrome

Yellow Canopy Syndrome (YCS) is a condition affecting Australian sugarcane that can lead to yield losses in excess of 30% in severely affected crops. The causal agent of this condition is unknown. Insect pests are well known causal agents of a wide variety of yield-limiting crop conditions, either as vectors of pathogens, directly through their feeding damage, or as transmitters of toxins, but little has been done to evaluate insects as a possible causal agent of YCS. This paper presents the findings of a one-year field trial in which insecticides from different chemical groups and an acaricide were tested to evaluate their effect on YCS incidence and severity. Results showed a delay in the onset of symptoms and a significant reduction in the severity of symptom expression following the application of neonicotinoid and pyrethroid treatments. These treatments also resulted in a significant yield improvement relative to cane in the untreated control. The acaricide treatment was ineffective. These findings suggest further work is warranted to determine which insects are being controlled and to identify the mechanism for the positive yield response. Key words Yellow canopy syndrome, insects, neonicotinoids, imidacloprid, bifenthrin