Foliar Disease Management in 2021

Tacy CalliesDiseases

By Megan Dewdney There were many challenges in 2020, but fortunately the Florida season for foliar citrus diseases was relatively normal. Little to no postbloom fruit drop (PFD) was reported during the 2020 bloom because of a sudden dry spell as the flowers opened. As spring 2021 approaches, the forecast is for a La Niña weather pattern with slightly warmer … Read More

Sneak Peek: February 2021 Citrus Industry

Tacy CalliesDiseases, Sneak Peek

While everyone strives to protect themselves from coronavirus disease, growers have an additional concern: protecting their trees from citrus disease. While HLB is of course the most damaging disease of citrus, there are other diseases that should not be overlooked. Disease management is the theme of the February 2021 issue of Citrus Industry magazine. University of Florida Institute of Food … Read More

Citrus Diseases to Pay Attention to

Tacy CalliesDiseases

Phytophthora and leprosis diseases can each substantially reduce productivity of a citrus tree, but when they attack trees already weakened by HLB, the result can be fatal. Ozgur Batuman, assistant professor at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), explained how co-infection impacts HLB-infected trees during a recent UF/IFAS webinar. PHYTOPHTHORA DISEASESPhytophthora species are soil-borne fungal pathogens … Read More

Georgia Citrus Pest and Disease Update

Tacy CalliesDiseases, Georgia, Pests

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 … Read More

Spotting the Symptoms of Citrus Black Spot

Ernie NeffDiseases

University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Extension recently provided the following information about identification of citrus black spot (CBS): Fruit symptoms can be observed around this time of year with the onset of color break and fruit maturity. Growers and agricultural workers should learn to identify the symptoms of CBS even if they are not located … Read More

Black Spot Likely in More Florida Counties

Ernie NeffDiseases


Although citrus black spot has only been detected in commercial groves in five Southwest Florida counties, it is still spreading and likely to be in additional counties, according to plant pathologist Megan Dewdney. The five counties with detections are Charlotte, Collier, Glades, Hendry and Lee. Dewdney is a University of Florida Institute of Food and Agricultural Sciences associate professor at … Read More

Emerging Trunk Disorders

Tacy CalliesDiseases

By Evan Johnson and Megan Dewdney The last two years have seen increasing grower questions and reports of citrus trunk disorders in Florida. Sometimes these reports are associated with sudden tree collapse. In many cases, phytophthora foot rot is initially suspected. Typically, the symptoms don’t quite match those of foot rot, and phytophthora cannot be isolated from the lesion. If … Read More

Citrus Advisory System Provides PFD Alerts

Ernie NeffDiseases

Beep. Beep. Beep. That’s the sound of an alert telling a citrus grower it’s time to spray fungicide to help prevent fruit from falling off the tree due to postbloom fruit drop (PFD). University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researchers have developed a Citrus Advisory System (CAS) that sends web-based alerts to growers via mobile devices. … Read More

Stem Pitting Could Develop in Florida Citrus

Ernie NeffDiseases

Citrus tristeza virus (CTV) stem pitting, which causes severe problems in Asia and other places, could develop in Florida, according to plant pathologist Amit Levy. The University of Florida Institute of Food and Agricultural Sciences researcher at the Citrus Research and Education Center discussed the disease at this year’s virtual Citrus Expo. Noting that “early detection is essential,” Levy said … Read More

Phosphite Best for Algal Spot

Ernie NeffDiseases

Algal spot had rarely been seen in Florida groves until fairly recently, Megan Dewdney reported in a virtual Florida Citrus Growers’ Institute presentation. The University of Florida Institute of Food and Agricultural Sciences plant pathologist said she started hearing from concerned orange growers within the past five years. Those growers told her that copper, the historical recommendation for the disease, … Read More

Viroid Found on Georgia Citrus

Ernie NeffDiseases

Hop stunt viroid (HSVd) was found on citrus in Georgia for the first time this year. University of Georgia Cooperative Extension warns that HSVd and other viroids could pose a threat to the state’s growing citrus industry in susceptible varieties. Leaf samples were collected in May and June from 12 different citrus plants in two nurseries in southern Georgia. Nine … Read More

Black Spot and Production Guide Updates

Ernie NeffDiseases

Megan Dewdney recently provided information about positive results from fungicide trials for citrus black spot, as well changes to the new Citrus Production Guide. Dewdney is a plant pathologist with the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), working at the Citrus Research and Education Center. Dewdney conducted the fungicide trials for black spot in a 20-year-old … Read More

Phytophthora Root Rot Management

Tacy CalliesDiseases, Tip of the Week

By Evan G. Johnson As September winds down, the fall root flush is starting and will continue through November/December. This is the largest root flush of the year that stores carbohydrate reserves for next spring. Coming out of the rainy season, phytophthora has had the chance to build up plenty of inoculum, especially in groves with a history of root … Read More

Citrus Disease: What to Watch for in Georgia

Tacy CalliesDiseases

The citrus greening disease (huanglongbing or HLB) that has devastated Florida’s citrus industry over the past decade has not affected Georgia commercial production. However, growers should still be aware of the potential danger it can bring. According to Jonathan Oliver, fruit pathologist and Extension specialist in the Department of Plant Pathology at the University of Georgia (UGA), all confirmed HLB-positive … Read More

APHIS Annual Report Highlights Citrus Efforts

Tacy CalliesDiseases, Pests

The U.S. Department of Agriculture Animal and Plant Health Inspection Service (APHIS) recently released an annual report titled “Plant Protection and Quarantine: Helping U.S. Agriculture Thrive — Across the Country and Around the World.” The document includes updates on efforts to manage citrus diseases. “PPQ (Plant Protection and Quarantine) stands shoulder-to-shoulder with citrus growers to combat citrus canker, huanglongbing (HLB … Read More

Canker Quarantine Expanded in Texas

Clint ThompsonCitrus, Diseases, Florida, Top

The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) announced June 30 it was immediately expanding the area quarantined for citrus canker in Texas. The agency added portions of Cameron County near San Benito and Brownsville to prevent the spread of the disease. APHIS confirmed the positive identification of citrus canker in two residential trees in San … Read More

Nursery Diseases at Planting: What to Watch for

Tacy CalliesDiseases, nursery

By Ozgur Batuman and Megan Dewdney Citrus nurseries work very hard and put forth considerable effort to reduce pest and disease problems. However, there continues to be problems with certain diseases, because the nursery environment for growing citrus trees is ideal for many pests and diseases. Basic principles of good nursery sanitation practices together with screening and removing suspected or … Read More

Citrus Canker Management Through the Year

Ernie NeffDiseases

Plant pathologist Megan Dewdney with the University of Florida Institute of Food and Agricultural Sciences offers suggestions for managing citrus canker at different times of the year. She is an associate professor at the Citrus Research and Education Center (CREC) in Lake Alfred. Dewdney suggests that copper sprays begin when fruit reach three-eighths of an inch in diameter in groves … Read More

Algal Spot: A Re-emerging Disease

Tacy CalliesDiseases

By Megan M. Dewdney Algal spot has not been seen frequently for many years, but in the last few years I have been getting more questions about identification and management. The disease is caused by a green alga, Cephaleuros virescens. The alga is not considered a parasite, as it grows superficially, but it does cause damage to trees if left … Read More

Citrus Leprosis Poses a Threat to Florida

Tacy CalliesDiseases

By Amit Levy, Ozgur Batuman, Peggy Sieburth and Lauren Diepenbrock Citrus leprosis is an exotic viral disease not currently present in Florida. This disease is of interest since it was reported in citrus in Florida and Brazil in the early 1900s, where it caused great crop and tree losses, but it was eliminated from Florida in the early 1960s. Currently, … Read More