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Below you'll find a list of all posts that have been categorized as “Diseases”
For the first time, scientists have been able to measure the speed of the Candidatus Liberibacter asiaticus (CLas) bacteria that causes HLB disease. CLas are injected into citrus trees by psyllids feeding on the trees’ sap. CLas relies on this sap to grow and spread throughout trees. Using a new statistical modeling analysis and measurement approach, plant pathologists were …
An update on citrus diseases in Brazil was part of a recent U.S. Department of Agriculture Foreign Agricultural Service (FAS) report. GREENING INCREASINGAccording to the 2021 citrus greening survey conducted by Fundecitrus, 43.4 million trees, or 22.37%, of the trees in the commercial area of the state of São Paulo and the western part of Minas Gerais are affected by …
A quarantine for Elsinoë australis, the fungal causal agent of sweet orange scab (SOS), was established in all of Baldwin and Mobile counties in Alabama to prevent the spread of the disease. The quarantine was established by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) in cooperation with the Alabama Department of Agriculture and Industries (ADAI). …
In recognition of biosecurity threats such as HLB, a new five-year biosecurity program, CitrusWatch, has been launched in Australia. This program is funded by Hort Innovation through the citrus R&D levy and by Plant Health Australia (PHA) using the citrus plant health levy. The program is led by PHA, with Citrus Australia coordinating program activities. The Northern Territory Department of Industry Tourism …
Xylella fastidiosa (Xf) bacterium causes incurable diseases that make plants wither and possibly die, scorching and browning leaves and reducing the size of fruit in a wide variety of important crops. Citrus variegated chlorosis is among the diseases that Xf causes. Pablo J. Zarco-Tejada and Tomas Poblete with the University of Melbourne describe the Xf bacterium as “the number one …
Information to help growers find and control citrus black spot (CBS), as well as CBS regulatory procedures, were provided in an Oct. 26 training workshop in Arcadia. The workshop was hosted by multi-county citrus Extension agent Ajia Paolillo. University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) plant pathologist Megan Dewdney discussed the pest’s lifecycle, potential spread due to …
By Amit Levy Citrus leprosis is an exotic viral disease not currently present in Florida citrus, although the virus is present in non-citrus hosts. This disease was reported in citrus in Florida and Brazil in the early 1900s, where it caused great crop and tree losses, but was eliminated from Florida in the early 1960s. In recent years, the disease …
Effective immediately, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) is establishing three new quarantine areas and expanding two existing quarantine areas for citrus canker in Cameron County, Texas, to prevent the spread of the disease. This action is necessary because APHIS confirmed the positive identification of citrus canker in citrus trees from residential areas in …
The title of Megan Dewdney’s Citrus Expo presentation was, “Shorten the skirts? Whether skirting improves citrus black spot fungicidal management.” The answer was “no,” based on trials she conducted to make that determination. But while skirting doesn’t appear to improve citrus black spot (CBS) fungicide programs, she pointed out that “there are other good disease management reasons to skirt.” Dewdney …
A saturated summer across the Southeast means more potential for development of phytophthora root rot disease in citrus trees. The impact on Georgia’s young trees could be devastating, says Jonathan Oliver, University of Georgia assistant professor and small fruits pathologist. Oliver implores Georgia’s citrus producers to stay vigilant with their fungicide sprays, as the wet conditions have not let up. …
University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) multi-county citrus Extension agent Ajia Paolillo discussed brown rot management in the September Extension newsletter, Citrus from the Ridge to the Valley. Her article follows. As we move into September, it is essential to remember that brown rot can impact yield, especially early varieties. Brown rot is caused by either …
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 …
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 …
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 …
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 …
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 …
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 …
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 …
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 …
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 …
