Protecting Trees From Phytophthora Disease

Tacy CalliesDiseases, Tip of the Week

By Evan G. Johnson It is time to start thinking about protecting the fall root flush that will start soon and 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 … Read More

Citrus Tristeza Virus Still in Florida

Ernie NeffDiseases

Citrus tristeza virus (CTV) is still present in Florida and can be transmitted to new trees, especially during brown citrus aphid outbreaks, according to the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS). A presentation about surveying for CTV was available at the UF/IFAS booth during Citrus Expo in August. The presentation noted that switching to sour orange … Read More

Packinghouse Day Updates: Greasy Green Disorder and Cold Hardy Citrus

Ernie NeffCold Hardy, Diseases

Updates on the so-called greasy green disorder and the Cold Hardy Citrus Association were presented at the virtual Packinghouse Day on Aug. 26.   GREASY GREENThe greasy green disorder affecting fruit primarily in Florida’s Indian River region has “been getting worse the past two seasons,” researcher Mark Ritenour reported. Ritenour is a University of Florida Institute of Food and Agricultural … Read More

Xanthomonas Key Finding Made

Ernie NeffDiseases

Scientists from Nanyang Technological University (NTU) in Singapore have identified a key mechanism by which the dangerous plant bacteria Xanthomonas can infect crops. The Xanthomonas bacteria, known as the “crop killer,” is a globally prevalent bacterium capable of infecting 400 different plant species. Citrus canker is caused by the bacterial pathogen Xanthomonas citri subsp. The NTU researchers identified the exact … Read More

Alabama Trying to Contain Citrus Canker

Tacy CalliesDiseases

How citrus canker arrived in Alabama is still unknown. What is certain is that it’s an issue the Alabama Department of Agriculture is determined to contain before it becomes a major problem, said Kassie Conner, director of the Auburn University Plant Diagnostic Lab, during a recent webinar. “The first trees that were found infected were in a landscape, and the … Read More

Canker Quarantine Revised in Texas

Ernie NeffDiseases

In late August, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) removed a portion of Harris County within the Braeswood area of Houston, Texas, from citrus canker regulations. APHIS reported that the successful partnership between itself and the Texas Department of Agriculture (TDA) has resulted in a citrus canker-free status in the area since 2016. On … Read More

Canker Eradication Efforts Underway in Texas

Ernie NeffDiseases

The Asiatic A strain of citrus canker was recently found in the Upper Gulf Coast area of Texas, posing a significant threat to the state’s commercial citrus production. The U.S. Department of Agriculture (USDA), the Texas Department of Agriculture and the Texas A&M University-Kingsville Citrus Center are collaborating on surveys to detect the disease. They are also removing and properly … Read More

Florida Black Spot Quarantine Expands

Ernie NeffDiseases, Regulation

The citrus black spot (CBS) quarantine in Florida was recently expanded in five Southwest Florida counties by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS). APHIS added 37 sections in Charlotte County, 17 sections in Collier County, 45 sections in Glades County, 68 sections in Hendry County and 28 sections in Lee County to the quarantine … Read More

Controlling Diplodia Stem-End Rot Before Harvest

Tacy CalliesDiseases

By Mark A. Ritenour, Jiuxu Zhang, Liliana M. Cano and Megan M. Dewdney The decay of fresh citrus fruit in Florida is usually caused by fungal pathogens that grow and develop in the hot and wet conditions typical to the state. While green and sometimes blue Penicillium molds and sour rot can cause Florida fruit to decay, the subtropical conditions … Read More

Grower Input Wanted on ‘Greasy Green’ Disorder

Ernie NeffDiseases

The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) is asking Florida fresh citrus growers and packers to complete a brief, anonymous survey about a disorder some call “greasy green.” The symptoms of the disorder are consistent with greasy spot, but a direct causal relationship has not been proven. The disorder may also be related to other possible … Read More

Treating Pathogens Without Antibiotics

Ernie NeffDiseases, Pests

Federal researchers announced that they have found an innovative way to treat pathogens (harmful bacteria) and pests in citrus trees and potato and tomato plants without the use of antibiotics. The researchers are with the U.S. Department of Agriculture’s (USDA) Agricultural Research Service (ARS). The research was done in collaboration with the University of Florida and AUM LifeTech Inc. The … Read More

Time for Brown Rot Management

Tacy CalliesDiseases, Tip of the Week

By Evan Johnson The Florida summer rainy season is in full swing, and there have been one or two root flushes by now. This is a good environment for increases in soil Phytophthora propagule counts. High counts have been seen this year, especially in Southwest Florida. While much of the focus may be on root rot, it is important to … Read More

First Citrus Canker Detection in Alabama

Ernie NeffDiseases

Citrus canker has been detected in a residential area of Baldwin County, Alabama, which is bordered by Florida and the Gulf of Mexico. Federal and state plant health officials confirmed the identification of the disease from foliage and fruit samples collected by the Alabama Department of Agriculture and Industries’ (ADAI) routine citrus survey.  This was the first detection of citrus … Read More

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 … Read More

A Trojan Horse for Citrus Disease

Ernie NeffDiseases, Research

Scientists are hoping the RNA of an obscure infection can one day be used like a Trojan horse to deliver treatments to citrus trees, possibly to combat HLB disease. The infection, citrus yellow vein disease, was discovered 64 years ago in Riverside, California, and has never been seen elsewhere in the world. Decades later, University of California (UC) Riverside researchers … Read More

CLM and Canker: Dangerous Summer Duo

Ernie NeffDiseases, Pests

Chris Oswalt details the connection between citrus leafminer (CLM) and citrus canker in the May/June Central Florida citrus Extension newsletter, Citrus from the Ridge to the Valley. He also offers some management tips. “I don’t think we can overstate the effect of leafminer damage on citrus foliage and the increased development of citrus canker lesions on damaged leaves,” the multi-county … Read More

New Anthracnose-Causing Fungus Identified

Ernie NeffDiseases

Researchers at the University of Melbourne have identified an Australian strain of fungus that causes citrus anthracnose. “Our research group at the University of Melbourne analyzed Colletotrichum collected from samples of anthracnose lesions on citrus leaves, twigs and fruit,” researchers Weixia Wang and Paul Taylor wrote. “The study identified six Colletotrichum species infecting Australian citrus. One of these is a … Read More

Effects of Grower Tools on Citrus Diseases and Roots

Ashley RobinsonDiseases, Root health

Citrus researchers at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) are taking a more comprehensive look at how tools to manage HLB affect young trees. The goal is to develop integrated approaches and update management practices for growers. After one year of the research project, some interesting results are already emerging. The research project, “Establishing Healthy … Read More

The Challenge of Solving Citrus Tree Diseases

Ernie NeffDiseases

“When a tree gets infected, there is generally no way to cure it,” University of Maryland virologist Anne Simon wrote in a recent white paper about invasive tree diseases. She explained that trees lack adaptive immune systems, so once infected they typically must tolerate the pathogen for the remainder of their lifespan. “In some cases, immunity can be provided by … Read More

Fungal Disease Management Recommendations

Ernie NeffDiseases

University of Florida multi-county citrus Extension agent Chris Oswalt discussed fungal disease management in the April Central Florida citrus Extension newsletter. Here is a summary: In Florida, fruit fungal diseases that are oftentimes problematic in the early spring are melanose, scab and alternaria brown spot, along with citrus canker. In the summer period, greasy spot is more of a problem, … Read More