Active Asian citrus psyllid (ACP) populations have been found in residential and commercial citrus in Lowndes and Wayne counties in Georgia during the past two months. Georgia citrus growers (both homeowners and commercial growers) are advised to inspect (scout) their trees immediately for signs of this important insect vector of citrus greening (Huanglongbing; HLB) disease. For specific recommendations regarding the identification of this insect pest and the treatment of possible infestations, please contact your local Extension agent. Additional information about this issue has been provided below.
Asian Citrus Psyllids, HLB, and Implications for Georgia Citrus
Figure 1. Asian citrus psyllid adults and nymphs on young citrus flush (left), adult and immature stages of the insect compared to a pencil tip to give a perspective on their size (right). (Photo credit: Apurba Barman)
As citrus growers likely know, ACP (Figure 1) is the only insect vector responsible for carrying and spreading the bacteria that cause citrus greening or HLB disease in U.S. citrus. This disease has reduced Florida’s citrus production by nearly 90% since it was first identified in 2005 on a homeowner’s citrus tree in South Florida. Although Georgia’s emerging citrus industry is not similar Florida’s industry with respect to size, climatic conditions, and production system, these recent finds suggest that the situation here in Georgia may be similar to the initial stages of the epidemic in Florida, which began after ACP was first detected in that state in 1998. In several of the recent Georgia locations where ACP has been found, HLB-infected trees have also been identified nearby, suggesting the strong potential for and/or confirming the psyllid transmission of this disease within the trees at these locations. Unfortunately, due to the tendency of disease symptoms to show up only after trees have been infected for months-to-years, it is likely that additional trees may be in the early stages of infection in these areas.
Figure 2. The southern half of Georgia, where most commercial citrus is currently located. Counties shaded in yellow include commercial and residential locations where active ACP populations have been detected within the past 24 months.
In addition to these recent finds of ACP infestations in Wayne County (two commercial groves) and Lowndes County (a single homeowner/residential setting), ACP populations were also found within two commercial citrus groves in Pierce County during late 2023 and 2024 (Figure 2). This is not good news. Until these recent finds, it had been hoped that the significantly cooler winter temperatures experienced in Georgia (versus the warmer winters typical in Florida’s citrus growing areas) would limit ACP survival and establishment in Georgia’s cold-hardy citrus production region. Nonetheless, despite significant freezing events occurring during the past three winters in South Georgia, the weather has not prevented these insects from establishing and persisting on citrus plants in Georgia.
So, what does all this mean to Georgia’s citrus industry? I believe that we are at a critical time when we must take steps based on the lessons learned from Florida’s citrus industry. If we want to keep our citrus industry growing, we must pledge to keep the insect (ACP) and HLB at bay. I believe that we are at the very initial phase of ACP spread, and it is still possible to keep this insect under control if decisive actions are taken immediately. However, homeowners, commercial citrus growers, the general public, the government, and institutions all must work together to accomplish this. For this mission, both monitoring (scouting) for ACP and control of this insect pest through insecticides will be essential.
ACP Monitoring/Scouting
Regularly using yellow sticky cards and visual inspections of the trees is key to determining the presence of ACP. New leaves (flushes) in citrus trees are a preferred site for ACP reproduction and feeding, and are a good starting place to look for this insect. Homeowner citrus trees, which likely have received little/no insecticide applications, could be a potential source for ACP. Similarly, trees in commercial groves that have not had serious insect issues previously may have received limited insecticide applications, and some of those trees may likewise support ACP populations. As such, it doesn’t matter whether the tree is in the backyard alone or sitting within a 20-acre commercial block, as long as it is a citrus tree, ACP can feed and reproduce on these trees to increase its population. Therefore, for both homeowners and commercial growers with citrus trees, to monitor for potential ACP populations, I recommend putting out yellow sticky cards on your citrus trees at this time. For homeowners, one card per tree should be sufficient. In commercial citrus groves, it is best to place at least 6-8 cards in total, especially on the edges of each block, since ACP activity is often first detected on the border row trees. The cards should be checked for ACP and replaced at least every two weeks (Figure 3).
Figure 3. Example of a yellow sticky card trap deployed on a citrus tree (left), sticky card with trapped ACP, indicated with red circles (right), and a close view of a trapped ACP (inset). (Photo credit: Apurba Barman)
To help with the identification of ACP on the traps, or for any questions related to the identification of and monitoring for ACP, please contact your county’s UGA Extension Agent. In the coming days, we will be providing more resources and information about workshops to help with ACP identification and scouting efforts. In the meantime, if you find ACP on sticky cards or see them on your trees, please get in touch with your respective UGA County Extension agent to confirm and arrange testing of these insects for the presence of HLB-causing bacteria.
Some options for where to purchase yellow sticky cards are provided below:
https://www.evergreengrowers.com/sensor-yellow-sticky-cards-3×5-with-grid-lines-and-hanger.html ($30 for 50 cards, 3 x 5 inch)
https://www.greatlakesipm.com/monitoring/traps/olson/glol061212-olson-sticky-strips-yellow-6-x-12-125cs ($173 for 125 cards, 6 x 12 inch)
https://alphascents.com/products/yellow-card-double-sided-8-x-5-5-in?variant=44944714727740 ($153 for 100 cards, 8 x 5.5 inch)
Control of ACP via Insecticide Applications
Controlling this insect via insecticides is critical to reduce or prevent the spread of HLB disease in Georgia and to protect Georgia’s citrus industry. Effective insecticides are available that can control both adult and immature populations of ACP. Upon finding ACP within your grove or on your trees, it is recommended to begin aggressive insecticide control measures. These include applying broad-spectrum insecticides such as pyrethroids (Baythroid, Danitol, Tombstone, Mustang Maxx) and neonicotinoids (Actara, Sivanto, Admire Pro), primarily to target the adult population. Depending on the level of population pressure and presence of immature (juvenile) ACP, soil applications of thiamethoxam (Platinum) and cyantraniliprole (Verimark) can be used to prevent population growth. (Please make sure to follow all insecticide label instructions, including rates, other recommendations, and precautions.)
