updates

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 …

barriers

Black Spot Scouting and Control

Ernie Neffblack spot

“The most important time to scout for black spot is when the fruit begin to change color,” said University of Florida Institute of Food and Agricultural Sciences plant pathologist Megan Dewdney. She has seen color change for Valencia oranges, the most commonly infected variety, from December to March. But she added it is usually late-February to early-March when citrus black …

barriers

Citrus Black Spot Quarantine Area Updated in Florida

Daniel CooperDiseases, Industry News Release

Effective immediately, the Animal and Plant Health Inspection Service (APHIS) is adding eight sections in Charlotte County, nine sections in Lee County, 28 sections in Hendry County, and five sections in Collier County to the citrus black spot (CBS) quarantine area in Florida. This action is in response to the confirmation of CBS during annual surveys conducted by APHIS and …

Citrus Black Spot Update

Ernie Neffblack spot, Diseases

Callie Walker with the Florida Department of Agriculture and Consumer Services (FDACS) recently gave an update on the citrus black spot quarantine in Southwest Florida. Walker is bureau chief of pest eradication and control for FDACS’ Division of Plant Industry and serves as statewide director for the Citrus Health Response Program. She summarizes the presentation she made at the Florida …

barriers

Hurricane Irma Raises Black Spot Threat

Ernie Neffblack spot, Diseases

University of Florida Institute of Food and Agricultural Sciences Extension pathologist and associate professor Megan Dewdney reported that U.S. Department of Agriculture (USDA) scientist Tim Gottwald thinks there’s a “fairly high” chance that Hurricane Irma spread citrus black spot. Black spot had been confined primarily to Southwest Florida, especially Collier and Hendry counties, before Irma hit the state with damaging …

What to Do if Citrus Black Spot Isn’t Near

Ernie Neffblack spot

University of Florida Institute of Food and Agricultural Sciences researcher Megan Dewdney addresses what growers should do if citrus black spot isn’t near their groves. She summarizes a presentation she made at a recent growers’ workshop in Sebring. “My few pieces of wisdom have been to tell people to just be conscious of their area and know whether they are …

citrus black spot

Citrus Black Spot Location and Management

Ernie NeffCitrus Expo, Pests

The citrus black spot (CBS) that emerged in Florida in 2010 apparently remains confined to Collier and Hendry counties, except for a single find in Polk County in 2013. “There’s a quarantine within those two counties (Collier and Hendry),” University of Florida researcher Jeff Rollins said in a Citrus Expo presentation. “The quarantine extends a little bit into Lee County, …

New Knowledge on Citrus Black Spot

Josh McGillCitrus

By Megan Dewdney, Jeff Rollins, Nan-Yi Wang and Ke Zhang Citrus black spot (CBS) has become established in the groves of Collier and Hendry counties. In other citrus-growing regions of the world where CBS is present, the sexual fruiting bodies of the fungus, known as pseudothecia, form in decomposing leaf litter. Approximately 50 to 180 days following leaf drop, the …

Essential Oil Could Help Prevent Citrus Black Spot

Kelsey FryCitrus, Citrus Greening

By: Robin Koestoyo FORT PIERCE, Fla. – Dipping fruit after harvest with hot water and essential oil dips may reduce postharvest development of citrus black spot (CBS) lesions per fruit by up to 50 percent, according to new University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) research. The new management techniques are the result of Jiaqi Yan’s recently …

Citrus Black Spot Control

Kelsey FryCitrus

University of Florida researcher Katherine Hendricks offered citrus black spot control suggestions to about 60 growers attending a fungal diseases seminar last week in Immokalee. She discussed cultural and chemical controls. The seminar was hosted by multi-county citrus Extension agent Mongi Zekri. Download Audio Sponsored ContentTake Advantage of Rising Temperatures to Treat for Fire AntsJune 8, 2026Make a Plan to …

milton

Hurricane Milton: Spotty Citrus Damage, Some Severe

Daniel Cooperhurricane

A few themes are unfolding as Florida’s citrus industry begins to assess Hurricane Milton’s damage. First, it could have been worse. The overall citrus losses do not appear to be as bad as those incurred from Hurricane Ian in 2022. Second, the hurricane affected nearly the entire Florida Citrus Belt, but damage varies greatly depending on the specific area. Reports …

greasy spot

Symptoms and Management of Brown Rot and Greasy Spot

Daniel CooperDiseases

University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) presenters on Aug. 30 discussed symptoms and management of the fungal citrus diseases brown rot and greasy spot. Plant pathologist and associate professor Megan Dewdney, the featured speaker, focused on management. Multi-county citrus Extension agent Mongi Zekri, who hosted Dewdney’s talk, described disease symptoms. BROWN ROT Brown rot is usually …

algal spot

Algal Spot an Increasing Problem in Florida Groves

Daniel CooperDiseases

Algal spot, not frequently seen in Florida citrus groves before 2015, has become more severe in recent years, University of Florida Institute of Food and Agricultural Sciences speakers reported Aug. 30. And the disease is likely to intensify as a problem with average temperatures increasing, said Megan Dewdney, associate professor of plant pathology at the Citrus Research and Education Center …

What To Do About Algal Spot

Tacy CalliesDiseases, Tip of the Week

By Megan Dewdney I did not need to visit my field trial to know that algal spot was in bloom on citrus in the last month. I have received many phone calls about it recently as growers notice the bright orange doughnuts on their tree limbs. For those unfamiliar with algal spot, it is a disease that occurs mostly on …

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, …

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 …

projects

Citrus Projects Funded by Plant Protection Act

Daniel CooperPests, Research, USDA

The U.S. Department of Agriculture (USDA) announced an investment of more than $90 million under Section 7721 of the Plant Protection Act to support 441 projects that will: Of the 441 projects, 421 fall under the Plant Pest and Disease Management and Disaster Prevention Program and 20 support the National Clean Plant Network. USDA will reserve approximately $17.2 million to support rapid …

flooding

Flooding Disrupts South African Citrus

Daniel CooperInternational, Weather

The U.S. Department of Agriculture Foreign Agricultural Service (USDA FAS) reported on disruption of citrus operations in South Africa due to flooding late last month. Heavy, persistent rainfall in South Africa’s Mpumalanga and Limpopo provinces caused widespread flooding and infrastructure damage. Waterlogged citrus orchards have hindered disease management and increased the risk of citrus black spot (CBS) infestation, threatening market …

Florida Citrus Show

Earn Continuing Education Units at the Florida Citrus Show

Daniel CooperEvents, FCS24, Florida Citrus Show

The Florida Citrus Show is only two weeks away, scheduled for March 12. The event will be held at the University of Florida Institute of Food and Agricultural Sciences Indian River Research and Education Center and the U.S. Department of Agriculture-Agricultural Research Service U.S. Horticultural Research Laboratory in Fort Pierce. The educational seminars have much to offer for both citrus …