Written collaboratively by Philip Rozeboom, Jonathan Kleinjan, Patrick Wagner, Brad McManus and Madalyn Shires.
Originally Submitted: May 12, 2023
We have received reports of winter wheat fields that are infested with aster leafhoppers (Figure 1). Aster leafhoppers are capable of producing feeding injury that is referred to as “hopper burn,” although the severity of the injury is much less than that observed when alfalfa plants are fed on by potato leafhoppers. Typically, aster leafhoppers aren’t present in large populations during the spring, but with the right weather conditions, very large populations can be observed in winter wheat. Warm weather in May and June along with adequate soil moisture can promote aster leafhopper infestations. Although the aster leaf hoppers have a negative effect on plant health, there are no economic thresholds for its management in winter wheat. Aster leafhoppers are generalists, and they will feed on many species of plants, including grasses and some garden vegetables. The concern with aster leafhopper infestations is the possibility for the transmission of aster yellows phytoplasma that can occur with feeding activity.
Aster Leafhopper Description
Adult aster leafhoppers are small, at approximately one-eighth of an inch long. They have a wedge-shaped body that is light green to yellow in color. The adult aster leafhoppers have clear wings that cover their abdomens. Although present on nymphs and adults, the two distinct spots present between their eyes when viewed from above are more easily observed on adults (Figure 2). The aster leafhopper is occasionally referred to as the six-spotted leaf hopper, due to the presence of the six distinct black markings that are observed on the front of the head (Figure 3).
Aster Leafhopper Feeding Injury
Aster leafhoppers have piercing-sucking mouthparts that are used to feed on the phloem of plants. The aster leafhopper mouthparts disrupt plant cells during feeding, which results in stippling (for example, white or yellow spots on the leaves). Excessive feeding results in yellow discoloration of the leaf and the characteristic symptoms of “hopper burn.” Hopper burn is often mistaken for drought stress, as the leaves of affected plants begin to turn yellow and will dry out beginning at the leaf tip (Figure 4).
Aster Yellows Phytoplasma Vector
Aster leafhoppers are competent vectors of aster yellows phytoplasma. Phytoplasma are a type of bacteria that behave similarly to a virus. However, the presence of the leafhopper is not always an indicator that aster yellows will also be present. The adult leafhoppers must acquire the phytoplasma from previously infected plants during a 30-minute or longer feeding. The aster yellows phytoplasma then takes approximately two weeks to incubate in the aster leafhopper before it can be transferred to new plants. Although acquisition of the phytoplasma takes a considerable time, once ingested and incubated, aster leafhoppers remain infectious for the remainder of their lives. Aster yellows symptoms are similar to those of Barley yellow dwarf virus. Economic losses in wheat have been associated with aster yellows infections in North Dakota, which were observed when large populations of the aster leaf hopper and high incidence of aster yellows were present. Aster yellows is a common disease of row crops, horticultural crops, and even weeds, so the potential for infection of wheat can exist each year, which makes disease symptom scouting important in management plans.
Management
Because there are no set management recommendations for aster leafhoppers, we recommend scouting wheat for their presence and making management decisions based on the presence of observable feeding injury and population size. The direct feeding by large aster leafhopper populations hasn’t been associated with yield loss, but the large populations may be an indicator of potential aster yellows phytoplasma risk.
Reference
- Knodel, J. 2015. Aster leafhoppers in winter wheat. North Dakota State University Extension.
- Lee, I.M., Gunderson-Rindal, D.E., Davis, R.E., Bottner, K.D., Marcone, C., Seemuller, E. 2004 ‘Candidatus phytoplasma asteris’ a novel phytoplasma taxon associated with aster yellows and related diseases. International Journal of Systematic and Evolutionary Microbiology, 54, pp. 1037-1048.
