Minimize Blemishes on Tangerines and Grapefruit

Tacy Callies Diseases, Tip of the Week

Megan Dewdney Since tangerines and grapefruit they are eaten fresh, a blemish-free peel is highly desired. Two diseases that frequently mar the peels of tangerines, and occasionally grapefruit, are Alternaria brown spot (ABS) and citrus scab. Both diseases cause symptoms on leaves and fruit. ALTERNARIA BROWN SPOTThe early foliar symptoms of ABS are small yellow flecks that quickly become larger …

Stem Pitting Disease Caused by Citrus Tristeza Virus

Tacy Callies Diseases

By Amit Levy, Peggy Sieburth and Ozgur Batuman When we hear or read about citrus tristeza virus (CTV), we usually think about the decline of sweet orange or grapefruit trees on sour orange rootstocks. However, there are other diseases caused by different isolates of the virus. One of these diseases is stem pitting, mostly caused by the VT isolate of …

Scout Early Bloom for PFD

Tacy Callies Citrus, Diseases, Tip of the Week

By Andre B. Gama and Megan M. Dewdney Postbloom fruit drop (PFD) of citrus is a disease caused mostly by the fungus Colletotrichum acutatum. This fungus survives by producing resting structures on leaves and stems. When flowers start to appear in groves, these resting structures produce spores that can cause PFD. However, the fungus requires specific weather conditions to be …

Foliar Disease Management in 2021

Tacy Callies Diseases

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 …

Sneak Peek: February 2021 Citrus Industry

Tacy Callies Diseases, 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 …

Citrus Diseases to Pay Attention to

Tacy Callies Diseases

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 …

Georgia Citrus Pest and Disease Update

Tacy Callies Diseases, 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 …

Spotting the Symptoms of Citrus Black Spot

Ernie Neff Diseases

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 …

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Black Spot Likely in More Florida Counties

Ernie Neff Diseases

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 …

Emerging Trunk Disorders

Tacy Callies Diseases

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 …

Citrus Advisory System Provides PFD Alerts

Ernie Neff Diseases

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. …

Stem Pitting Could Develop in Florida Citrus

Ernie Neff Diseases

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 …

Phosphite Best for Algal Spot

Ernie Neff Diseases

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, …

Viroid Found on Georgia Citrus

Ernie Neff Diseases

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 …

Black Spot and Production Guide Updates

Ernie Neff Diseases

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 …

Phytophthora Root Rot Management

Tacy Callies Diseases, 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 …

Citrus Disease: What to Watch for in Georgia

Tacy Callies Diseases

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 …

APHIS Annual Report Highlights Citrus Efforts

Tacy Callies Diseases, 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 …

Canker Quarantine Expanded in Texas

Clint Thompson Citrus, 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 …

Nursery Diseases at Planting: What to Watch for

Tacy Callies Diseases, 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 …