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Submitted to: Proceedings Washington State Potato Conference
Publication Type: Proceedings Publication Acceptance Date: 2/1/2004 Publication Date: 8/15/2004 Citation: Munyaneza, J.E. 2004. Leafhopper population dynamics in the South Columbia Basin. Proceedings of 43rd Annual Washington State Potato Conference and Trade Show. Moses Lake, WA. p.51-58. Interpretive Summary: A serious epidemic of purple top disease of potato occurred in the Columbia Basin of Washington and Oregon in 2002 growing season and caused very significant losses to potato fields from Boardman and Hermiston in the south to Moses Lake in the north. There were also indications of reduced tuber quality resulting from diseased plants. The same disease was observed in 2003 growing season, especially in organic potato fields. Symptoms in affected potato plants include a rolling upward of the top leaves with reddish or purplish discoloration, moderate proliferation of buds, shortened internodes, swollen nodes, aerial tubers, and early plant decline. These symptoms resemble very much those of purple top caused by psyllid damage or phytoplasma infection, and in some cases to those caused by potato leafroll virus (PLRV). Early investigation of the cause(s) of the disease indicated that leafhopper transmitted phytoplasmas may have played a significant role in this disease epidemic. Information on insects vectoring this purple top disease of potato and their population dynamics is key to appropriately manage this disease in potatoes. Leafhoppers are easy to control and most registered foliar insecticides are effective in providing good control. However, leafhopper monitoring and sampling is crucial for timely insecticide applications and effective management of leafhopper transmitted diseases such as this potato purple top. Our leafhopper sampling results showed the population dynamics of different leafhopper species at several locations throughout the south Columbia Basin of Washington and Oregon during the 2003 growing season. Technical Abstract: Leafhoppers are strongly suspected to be the vectors of a recent epidemic of purple top disease of potato that occurred in the Columbia Basin of Washington and Oregon. A phytoplasma belonging to the clover proliferation group (16SrVI-A) was detected in diseased potato plants and is thought to be the disease causal agent. Results from our leafhopper monitoring and sampling in and/or near affected potato fields during the 2003 growing season throughout the south Columbia Basin indicated the presence and population dynamics of several leafhopper species, including Circulifer tenellus, Macrosteles spp., Ceratagallia spp., Dikraneura spp., Exitianus exitiosus, Ballana spp., Colladonus spp., Amblysellus spp., Paraphlepsius spp., Balclutha spp., Latalus spp., Empoasca spp., and Erythroneura spp. Leafhopper species composition was almost the same in all sampled locations. Most of the leafhopper species found in weeds and crops near potatoes were also present within potato fields. Although leafhoppers were observed in weeds near potato fields early spring, most leafhopper species seem to invade potatoes early summer. |
