Georgia Citrus Pest and Disease Update

Tacy Callies Diseases, Georgia, Pests

Alternaria leaf spots

As the Georgia citrus industry continues to grow and prosper, growers should be aware of the potential signs of citrus pests and diseases that could be looming in their groves.

Bill Barber, Certified Crop Advisor and owner of Barber Ag Services, delivered a presentation during the 2021 virtual Southeast Regional Fruit and Vegetable Conference. He addressed pests and diseases presently in Georgia production in addition to some other issues that could be of future concern to growers.

According to Barber, melanose has been a very prevalent disease across Georgia citrus production. Although all citrus varieties are susceptible to melanose, grapefruit seem to be the most vulnerable. He recommends applying fungicide after fruit set, around late April, and then continuing application every three to four weeks until July or early August.

Alternaria brown spot is another disease commonly seen throughout the state’s citrus-growing area that can cause fruit drop. Foliar infection appears as brown spots or blotches surrounded by a yellow halo. Fungicide applications should occur when the spring flush is at one-quarter to one-half expansion and again at full leaf expansion. If needed, a third spray can be applied shortly after petal fall.

Also problematic is citrus leafminer. According to Barber, this pest is extremely difficult to control with a topical treatment. To manage citrus leafminer, he recommends drenching the base of trees with a systemic pesticide once a month.

Additionally, wind scar is of great concern. Although not a disease or pest, the damage that is caused by the fruit contacting foliage or twigs during wind movement can be detrimental to growers producing for the fresh fruit market.

Wind scar is “going to be a tremendous issue for us in the future as we try to compete with states like California, which has a totally different climate. Their trees grow differently, and they don’t have the same issues that we do,” Barber says. “Some type of windbreak is going to be critical for future crops to minimize external defects.”

Looking ahead, there are several pests and diseases Barber has on his radar that he believes growers should be aware of and monitor for.

Satsumas are very susceptible to citrus scab. The disease causes wart-like scabs on leaves and fruit, a huge problem for the fresh market. Barber recommends controlling the disease aggressively if it appears because it can spread rapidly.

Barber also believes citrus blight could be a future concern for Georgia. Blight has been present in Florida for more than 100 years but there is no known cure for the disease since researchers have run into a dead end for the cause of the disease and control measures. Although blight may never make an appearance in Georgia, the disease attacks rootstocks that the state’s growers depend on.

As always, growers should vigorously monitor for citrus greening. Growers should contact their local county Extension agent immediately if they spot any signs of greening in their groves.

This article was written by Ashley Robinson, AgNet Media communications intern in Gainesville, Florida.