Apurba Barman, assistant entomology professor at the University of Georgia (UGA), recently wrote about citrus leafminer (CLM) damage resuming in Georgia groves. His article provided management recommendations, including timing of insecticides. Edited excerpts follow:
PEST DAMAGE
As the temperature rises, so does the potential for CLM attack. CLM is a serious pest resulting in feeding damage to young shoots and leaves
The indirect risk of CLM damage is the potential incidence of citrus canker. Citrus canker requires a moist environment and an opening in plant tissues to enter. CLM damage can provide that opening for the bacterial pathogen and aid in the disease’s spread.
CLM preferentially attacks only the new growth (known as flush) of the plant such as shoots, leaves and buds. In South Georgia, there are typically three major flushing events in most citrus cultivars. CLM takes advantage of new flush, increasing the risk of the pest in groves.
In the last two years, UGA researchers have continuously monitored CLM in three commercial citrus groves in Georgia’s Tift, Berrien and Worth counties. It is typical for CLM to become active in mid-May and remain present until the end of the year. The peak CLM population occurs in July and September. The population appears to dip in August, likely due to the intense heat.
POPULATIONS PICKING UP
Researchers have not seen any leafminer damage until recently. Although there was a spring flush on citrus trees during April, there was no damage to that growth because CLM were not active. Now that the summer flush is beginning, and the leafminer population is picking up, expect to see damage from leafminer feeding going forward. Every time there is new growth on the plant, it will be attacked by leafminers unless insecticide treatments are made to manage the population.
Not all citrus varieties are equally susceptible to CLM. For example, grapefruit varieties (Ruby Red, Star Ruby) and Shiranui mandarin appear to be more susceptible than other citrus varieties such as satsumas, Tango and navel. However, almost all varieties suffer some damage from leafminer attack.
TREATMENT TIPS
Growers should prepare early for the leafminer attack, especially for the summer flush and onward. As soon as you expect to see new growth, treatment should begin without delay.
A field trial in a commercial grove in Tift County during 2025 indicated that Exirel (cyantraniliprole) and Admire Pro (imidacloprid) are effective against citrus leafminer. Movento (spirotetramat) and Sivanto (flupyradifurone) are moderately effective.
The best management approach for CLM starts with monitoring of moth activity by using pheromone traps. While there is no definite number of moths on the traps to determine insecticide timing, the number of moths has been observed to increase rapidly after mid-May. So, fewer moths (10 to 20 per trap) in early May is an indicator that an insecticide application is needed in the following weeks.
See Barman’s full article here.
Source: UGA
Share this Post