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 …
Best Practices for Brown Rot Management
By Megan Dewdney The Florida rains have finally come this summer, just in time for early-season fruit to start the maturation process. This means there is some risk of brown rot in early sweet oranges and grapefruit. Much of Florida has been getting summer storms, wetting the soil. While this is excellent in general, the downside is that it allows …
What To Do if Brown Rot Surprises You
By Megan Dewdney It is late summer or early fall, and the usual time to consider brown rot treatment options has passed. However, you smell a sharp fermented fruit odor. When you look closer, fruit have the telltale soft brown lesions of brown rot. What options exist to minimize losses now? It is too late for the traditional control options …
Symptoms and Management of Brown Rot and Greasy Spot
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 …
Reduce Fruit Drop From Phytophthora-Induced Brown Rot
By Chris Oswalt During this time of the year, Florida growers should be aware of the potential for the development of citrus brown rot disease. It can infect fruit at color break. If severe, the disease can cause a significant amount of infected fruit to drop. For this reason, groves with a history of brown rot in areas that recently …
Brown Rot Could Be on the Horizon for Florida
By Megan Dewdney It is summer in Florida, and the early fruit are maturing. This is always a risky time for brown rot in early sweet oranges and grapefruit cultivars. The summer rains have been happening, but they have been intermittent depending on location. This means that phytophthora propagule counts may vary depending on how much rain has occurred in …
Brown Rot Management Advice
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 …
Time for Brown Rot Management
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 …
Brown Rot Basics
Plant pathologist Megan Dewdney with the University of Florida Institute of Food and Agricultural Sciences discussed the basics of brown rot and its control at a recent disease seminar in Immokalee. Approximately 60 growers and others attended the seminar held at the Southwest Florida Research and Education Center. Brown rot is especially prevalent in early-season citrus varieties. “It’s particularly problematic …
Brownsville Mexfly Quarantine Removed in Texas
Federal and state agriculture officials on Nov. 14 removed the Mexican fruit fly (Mexfly) quarantine in Brownsville, Cameron County, Texas. The quarantine was removed after three generations elapsed with no additional detections in the area. The action was taken by the U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) and the Texas Department of Agriculture (TDA). …
The Past and Potential of Parson Brown
By Gary K. England and Manjul Dutt The Parson Brown is an early-season sweet orange that was identified in 1875 by J.L. Carney and named the Carney Parson Brown (CPB). In a 1923 article titled ‘History of the Parson Brown Orange,’ E.L. Carney described how his brother Capt. J.L. Carney sought a sweet orange of acceptable quality for budding onto …
Protecting Trees From Phytophthora Disease
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 …
Controlling Diplodia Stem-End Rot Before Harvest
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 …
Phytophthora Root Rot Management
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 …
Control of Stem-End Rot of Fresh Citrus
By Mark A. Ritenour, Jiuxu Zhang and Megan M. Dewdney Decay of fresh citrus fruit is most often caused by fungal pathogens that grow and develop in the hot and wet conditions typical in Florida. While green and blue molds (Penicillium digitatum and Penicillium italicum) and sour rot (Galactomyces citri-aurantii) are the most common postharvest citrus diseases worldwide, the subtropical …
Florida Citrus Disease Updates
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 …
How To Determine if the Actual Production History Policy Will Be Beneficial
By Ariel Singerman Between the 2021–22 and 2023–24 citrus seasons, Florida orange growers were more likely to receive indemnity payments under the Actual Production History (APH) crop insurance policy compared to the Dollar Amount policy. Moreover, when indemnities were paid, the APH policy provided a higher average payout. This raises the question: Will APH continue to be advantageous for Florida orange …
Proper Site Selection Essential for Phytophthora Prevention
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 …
All In For Citrus Podcast, June 2025
In the June All In For Citrus podcast, Michael Rogers gives an update on some of the activities keeping University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researchers busy this summer. Rogers is the director of the UF/IFAS Citrus Research and Education Center in Lake Alfred. One of their big projects is helping to coordinate the citrus seminars …
Problematic Diseases Following Hurricanes
Hurricanes bring immediate tree damage from high winds and torrential rainfall, but storms also can lay the groundwork for citrus disease problems. Soon after Hurricane Milton passed through citrus-growing regions, the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) hosted a webinar that covered various topics including post-storm disease management. CANKER Megan Dewdney, UF/IFAS associate professor of plant …

























