Clemson University scientists have begun the first publicly available chemical trial aimed at controlling two-spot cotton leafhopper infestations in hibiscus plants, a major step toward protecting the ornamental horticulture industry.
The two-spot cotton leafhopper, a fast-spreading pest, threatens hibiscus and other ornamental plants. The trial, conducted at Clemson's Pee Dee Research and Education Center near Florence, South Carolina, provides nursery growers with the first science-based data on chemical control for this pest in a nursery setting.
Zee Ahmed, assistant professor and Clemson Extension specialist in turf and ornamental entomology, is leading the study, along with graduate students Nisha Yadav of Rewari, India, and Peilin Tan of Beijing, China, and research specialist Shawn Chandler.
© Clemson UniversityThe two-spot cotton leafhopper, a fast-spreading pest, threatens hibiscus and other ornamental plants.
A pest on the move
Native to Asia, the insect — also known as the cotton jassid — was first detected in the Caribbean in 2023 and subsequently in Florida in 2024. By 2025, it had spread to Alabama, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Texas. Experts warn its range could expand as infested plants are shipped across state lines.
The leafhopper causes "hopperburn," which turns leaves yellow, red or brown, curls them and eventually kills them. Damage often appears to be a nutrient deficiency or disease, making early detection difficult. Females lay eggs inside leaf veins, where they are protected from insecticides and natural predators.
"Eggs are largely unaffected by insecticides," Ahmed said. "By the time symptoms appear, the infestation is already well underway."
© Clemson UniversityLeft: Adult leafhopper observed on host foliage, with dorsal view and scale bar. Right: Nisha Yadav and Peilin Tan collecting field data during the chemical trial.
Why hibiscus matters
The pest feeds on many plants, including cotton, okra, eggplant, and soybeans, but poses a particular threat to ornamentals such as hibiscus. These plants allow leafhopper populations to persist when agronomic crops are out of season.
Reports from other countries show yield losses of 30% to 50% in susceptible crops, underscoring the need for effective control strategies.
The first public chemical trial
To date, no publicly available chemical trial has targeted the two-spot leafhopper on hibiscus in U.S. ornamental production. Ahmed's team tested six insecticides on hibiscus plants grown in 5-gallon containers and infested with leafhoppers. They evaluated knockdown and short-term residual efficacy at seven and 14 days after treatment.
Products tested included HachiHachi SC (tolfenpyrad, Group 21A), Altus (flupyradifurone, Group 4D), Mainspring GNL (cyantraniliprole, Group 28), Ventigra (afidopyropen, Group 9D), Safari 20SG (dinotefuran, Group 4A), and Talstar Professional (bifenthrin, Group 3A).
Promising results
HachiHachi SC and Altus consistently reduced adult and nymph populations at both intervals. Mainspring GNL provided rapid adult knockdown at seven days, but populations rebounded by Day 14. Ventigra and Safari 20SG showed variable results, while Talstar Professional had mixed success against nymphs.
"Insecticides that spread through the plant or across the leaf worked better on young insects feeding on the leaves," Ahmed said. "But none of the products affected the eggs."
© Clemson UniversityIntegrated pest management strategies for nursery and greenhouse environments, including cultural/mechanical controls (e.g., sanitation, spacing, trap crops) and chemical options organized by IRAC group and usage setting. Adapted from Yadav, N., Tan, P., and Ahmed, M.Z. (2025). Field guide for Two-spot Cotton Leafhopper. GrowerTalks, December Issue.
Practical guidance for growers
To control this pest, the scientists recommend Regular scouting with a 10x to 30x hand lens; Matching treatments to life stages; Checking plants at seven and 14 days after treatment; Rotating insecticides by IRAC mode-of-action groups; and Using biological and cultural controls when possible.
"Routine scouting and life-stage-based product choices are the most practical steps to keep small problems small," Ahmed said.
Resistance concerns
Studies from the pest's native range show reduced sensitivity to some insecticides. Ahmed warns resistance could develop quickly if growers rely on a single product.
"Rotating chemistries and integrating nonchemical tactics are essential," he said.
A model for future research
The trial sets a precedent for publicly available chemical screenings in ornamental entomology. Results will help develop a field guide for growers, including identification tips, scouting methods and control options.
"This is about more than just one pest," Ahmed said. "It's about building a framework for how we respond to emerging threats in ornamental production."
Looking ahead
As the leafhopper spreads, Ahmed said the need for science-based management will grow. Clemson's trial represents a critical first step.
"This pest is small, but the impact can be big," Ahmed said. "With the right tools and strategies, we can protect our plants, our businesses and our landscapes."
Source: Clemson University
