Cotton Jassid. What we know and what we don’t know (Roberts)
December 22, 2025
Cotton Jassid, Amrasca biguttula, was first observed in Georgia on July 9, 2025. Who would have ever thought that jassids would be detected in basically all cotton producing counties in Georgia by late September. Who would have ever thought we would treat approximately 60 percent of Georgia cotton for this invasive pest in 2025. I for one did not expect this. Jassid infestations were highest in southeast Georgia, the first commercial field was treated for Jassids in late July in Appling County. Jassids are native to the Indian subcontinent and were first found in the US in Florida during 2024 (found in Puerto Rico in 2023). Currently jassids have been detected in TX, LA, MS, TN, AL, FL, GA, SC and NC. Insecticides were used to control jassids in GA, FL, AL, and SC.
Cotton Jassids are small leafhoppers with piercing-sucking mouthparts. Jassids feed on the underside of leaves and inject a salivary toxin during feeding. Plant damage in response to jassid feeding and the toxin includes hopperburn symptoms which progress from slight yellowing on the leaf margins, to reddening, and potentially desiccation of damaged leaves. Hopperburn symptoms can progress rapidly. We observed many fields which changed from green to red in 2 weeks. Leaves may also be crinkled or appear puckered. Jassid infestations and plant damage were initially observed on field edges during 2025. When facing a new invasive insect pest, there are several questions we must first address when developing a management plan.
Question #1: How do you kill it? We initially conducted lab bioassays looking for efficacious insecticides. By mid-August we were able to conduct small plot efficacy trials on cooperating grower fields. Insecticides selected included active ingredients which are used for control of jassids in India and insecticides which are used for insect pest management in Georgia for various pests. Insecticide efficacy trials were also conducted by colleagues in AL, FL, and SC. We identified effective insecticides and can group those in three groups (good to excellent, fair to good, and poor). It is important we understand what each of the active ingredients brings to the table in terms of jassid control as we will need to rotate insecticides for resistance management.
Question #2: Does it matter? The question more specifically is do jassids reduce yield. The simple answer is yes. To date yield losses in our trials have averaged 18 percent with a range of 1 to 46 percent yield loss. We have observed a good correlation relating to actual jassid counts and yield. However, when jassids infest cotton (growth stage) and populations build to damaging levels is likely very important in terms of potential yield loss. In 2025 we tended to initially see jassids on early planted cotton which was in mid to late bloom. However, observations suggest that our greatest yield loss occurred on later planted cotton. Two potential reasons for greater yield loss in late planted cotton. Jassids infested later planted cotton earlier in the bloom cycle and jassid populations were much higher in September compared to August.
Question #3: When does it matter? What is an appropriate threshold to initiate an insecticide application? Based on the literature, published thresholds in India ranged from 1-5 jassids per leaf. Our suggested threshold got more aggressive during the year based on observations and field trials. As we enter 2026, our suggested threshold will be 1 jassid per leaf. Based on preliminary data, we recommended that scouts count jassids on the 4th mainstem leaf below the terminal. As we have reviewed data from our trials and the southeast, this monitoring and threshold appears to be acceptable if jassids infest cotton during the same time frame (late July and August). There is no question that jassids will require all cotton to be scouted. Growers cannot miss or be late with a needed insecticide when jassids are above threshold.
What we do not know: we are receiving many questions regarding jassids in 2026 and I am getting tired of saying we don’t know, but it is what it is. Models suggest that jassids can infest cotton anywhere it is grown in the US. We do know that jassids are impacted by cold temperatures, similar to what we see with whiteflies. I fully expect jassids to be a pest of Georgia cotton for the foreseeable future. The bigger question is when will jassids infest Georgia cotton in 2026. Growers clearly demonstrated their ability to manage jassids effectively when they infested cotton during late July and August. When all the dust settled, many growers did not add additional trips across the field, we just had to spend additional money on insecticides going in the tank. If we must treat earlier in the year, that will likely add trips across the field and even more expense on insecticides. If they infest cotton earlier, do we need to be more aggressive with management? There are many questions and only a few answers.
Jassid management in 2026 will continue to be evolving. As we did in 2025, we will provide the most current management information available to county agents. So, everyone needs to make sure they are on a county email listserv.