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Below you'll find a list of all posts that have been categorized as “Diseases”
For the first time in Brazil, Fundecitrus has identified evidence of partial resistance of the fungus Phyllosticta citricarpa, which causes citrus black spot, to fungicides of the strobilurin group. This finding corroborates warnings issued by growers and technicians during the 2024–25 season regarding failures in controlling the disease in areas of the São Paulo Citrus Belt. SAMPLE STUDY A study …
Freeze damage to Florida citrus could lead to a buildup in certain diseases. One, in particular, is a major threat, believes Megan Dewdney, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) associate professor in plant pathology and Extension specialist. “Our big concern in terms of foliar problems is going to be melanose. Just as a reminder, melanose produces …
By Megan Dewdney The recent freeze events of the last few weeks have scrambled the plans of citrus growers. It will take several weeks to months to understand the extent of the damage caused by the unusually cold weather. MELANOSE There is at least one disease that is highly likely to be worse than in other years. Melanose is likely …
Agriculture officials have expanded the areas quarantined for citrus greening disease (known as huanglongbing or HLB) in California. The quarantined area in the Corona area of Riverside County was expanded by 37 square miles. The San Juan Capistrano quarantined area of Orange County was expanded by 18 square miles. The actions were taken by the U.S. Department of Agriculture Animal …
Several Fundecitrus researchers recently made presentations at the Brazilian Workshop on Plant Disease Epidemiology, held in Pirenópolis, Goiás. The scientists discussed studies on disease epidemics affecting agricultural crops and management strategies. CITRUS FLOWER ROT FORECASTING Geraldo Silva Junior addressed the citrus flower rot forecasting system — developed in partnership with Luiz de Queiroz College of Agriculture University of São Paulo(ESALQ/USP) …
The new Citrus Plant Protection Guide 2025-26 from Australia’s New South Wales Department of Primary Industries and Regional Development (NSW DPIRD) is available online. The seventh edition of the guide provides up-to-date information on all aspects of managing pests and diseases in citrus orchards and includes updates on NSW DPIRD projects. Some of the projects are funded by Hort Innovation …
Federal agriculture officials on Nov. 25 announced the expansions of the areas quarantined for sweet orange scab (SOS) and huanglongbing (HLB) diseases in California. The U.S. Department of Agriculture Animal and Plant Health Inspection Service (APHIS) in cooperation with the California Department of Food and Agriculture (CDFA) enacted the expansions. SOS The SOS quarantined area has been expanded by 5 …
Plant pathologist Megan Dewdney on Nov. 20 presented updates on greasy spot, greasy-green, citrus black spot (CBS) and phytophthora brown rot. Dewdney is a University of Florida Institute of Food and Agricultural Sciences associate professor and Extension specialist at the Citrus Research and Education Center. GREASY SPOT AND GREASY-GREEN Dewdney reported that control measures for greasy spot, caused by the …
The Florida Fruit & Vegetable Association (FFVA) recently provided comments to the Office of the United States Trade Representative as part of the annual review of foreign barriers to U.S. exports and investment. The FFVA letter noted injury to Florida citrus caused by low-priced imports from Mexico and the European Union’s use of scientifically unjustified, non-tariff trade barriers. Letter excerpts …
Citrus canker, a federal and state regulated plant disease, has been detected in Mobile County, Alabama. As required by federal law, the Alabama Department of Agriculture and Industries (ADAI) will establish a citrus canker quarantine for the county. The Auburn University Plant Pathology Lab confirmed the first detection from foliage and fruit samples collected during ADAI’s routine citrus survey. The …
Recent research has shown that systemic acquired resistance (SAR) sprays can protect young citrus tree flushes from Asian citrus psyllid (ACP) feeding, HLB and citrus canker. ACP is the vector that spreads HLB disease from tree to tree. Researchers with the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) and Bayer Crop Science report that SAR sprays can …
The University of Georgia (UGA) has disease labs and clinics to help citrus producers determine what diseases are impacting their trees. Jonathan Oliver, UGA assistant professor and small fruits pathologist, highlights the diagnostic facilities that growers can take advantage of. “We have a lab in Tifton, the Plant Disease Clinic, that can accept samples from commercial citrus,” Oliver said. “We …
Federal and state officials recently expanded the area quarantined for citrus greening disease, also known as huanglongbing or HLB, in California. They expanded the quarantined area in the San Clemente area of Orange and San Diego counties by 81 square miles. The action was taken by the U.S. Department of Agriculture Animal and Plant Health Inspection Service (APHIS) in cooperation …
By Megan Dewdney Sometimes there is an unfortunate coincidence between the timing of fruit changing color and rain events. This can set up a situation where brown rot occurs unexpectedly and growers need to stop the disease after it has begun. CONTROL OPTIONS By this time of year, the traditional brown rot control measures are less effective. These are primarily …
Vulnerability of citrus trees to phytophthora root rot is a concern for cold-hardy growers. But there are precautions that producers can implement that will guard against infection buildup. One of those precautions includes site selection and not planting trees in poorly drained locations, according to Jonathan Oliver, University of Georgia assistant professor and small fruits pathologist. “Site prep is really …
A citrus disorder called greasy green has plagued Florida grapefruit producers for several years, causing a significant reduction in profits. University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Associate Professor and Extension Specialist Megan Dewdney discussed the disorder and its management at the Citrus & Specialty Crop Expo in August. Dewdney works at the UF/IFAS Citrus Research and …
Phytophthora root rot’s impact on young citrus trees is concerning for groves in the cold-hardy citrus region of North Florida, South Georgia and South Alabama. Newly planted trees are more vulnerable to the disease than older, established trees, says Jonathan Oliver, University of Georgia assistant professor and small fruits pathologist. He discussed the disease’s impact during the Citrus Grower’s Summer …
Federal and state agriculture officials have expanded the quarantine for citrus greening in the Perris area of Riverside County in California by 33 square miles. The U.S. Department of Agriculture Animal and Plant Health Inspection Service (APHIS) in cooperation with the California Department of Food and Agriculture (CDFA) expanded the quarantine. The measure parallels the intrastate quarantine that CDFA established …
An Iranian study in controlled greenhouse conditions has enhanced the understanding of the influence of rootstocks on limes infected with witches’ broom disease of lime (WBDL). The study has also led to the acknowledgement that WBDL management may require tolerance of both scions and rootstocks. Authors of an article about the study are Samaneh Raheb, Sina Noorizadeh and Morteza Golmohammadi, …
Citrus greening disease has yet to find its footing in Georgia. But that doesn’t mean it can’t or won’t eventually. Mary Sutton, University of Georgia assistant professor and citrus Extension specialist, discussed the ramifications of citrus greening during the recent Southeast Citrus Update in Lyons, Georgia. “If we get greening established here, we’ll start seeing lower and lower production on …
