By Tianna DuPont, WSU Extension; Tobin Northfield, WSU Entomology, September 7, 2023
Leafhopper population numbers are typically higher after harvest and data suggest that leafhoppers only transmit in the second and third generations, in August and October. It is critical to monitor and manage leafhopper vectors after harvest during this high-risk period.
Monitor Populations
Use yellow sticky cards or sweep nets to monitor your leafhopper population. Place traps near orchard borders, but within the block, in areas of concern in your block and throughout block. Approximately one trap per two acres. Monitor weekly. Use presence (an average of one leafhopper per trap) as a threshold to spray. Identify leafhoppers that vector X-disease phytoplasma. See gallery of insect images.
Rotate Effective Leafhopper Products
Manage leafhoppers when they are present – generally after harvest through October based on monitoring. If leafhoppers are present spray rotating between pesticide groups. With the residual of common (conventional) products sticky cards will likely show 21-30 days of control necessitating 4 to 6 after harvest sprays per season. Remember it takes several weeks after feeding on an infected plant for a leafhopper to be able to transmit the phytoplasma. The phytoplasma has to pass through the insect gut, into the ‘blood’, and to the salivary glands before it can be excreted into a new plant with the saliva. Every two to three weeks sprays should be the shortest interval needed. More frequent sprays will mean you likely run out of legal applications before the end of the season when transmission is likely to be highest. See product efficacy tables.
Additional Information
Contacts
Tobin Northfield
WSU Entomology
tnorthfield@wsu.edu
Tianna DuPont
WSU Extension
(509) 293-8758
tianna.dupont@wsu.edu
Fruit Matters articles may only be republished with prior author permission © Washington State University. Reprint articles with permission must include: Originally published by Washington State Tree Fruit Extension Fruit Matters at treefruit.wsu.edu and a link to the original article.
Use pesticides with care. Apply them only to plants, animals, or sites listed on the labels. When mixing and applying pesticides, follow all label precautions to protect yourself and others around you. It is a violation of the law to disregard label directions. If pesticides are spilled on skin or clothing, remove clothing and wash skin thoroughly. Store pesticides in their original containers and keep them out of the reach of children, pets, and livestock.
