The UF/IFAS Tip of the Week shares tips for control options when there is a late detection of brown rot in citrus.

According to the UF/IFAS Tip of the Week, the time for preventative control of brown rot in citrus. But what are your options if you notice it now? The article, published online in Citrus Industry Magazine, shares treatment options for controlling brown rot if it’s detected once the timeline for traditional control options like phosphite applications has passed. See them below.

Treatment of Late Detection of Brown Rot

The article shared these late treatment options if you find your fruit has “the telltale soft brown lesions of brown rot:”

  • “Copper applications are a possibility with the advantage of killing the inoculum that forms on the outside of the fruit. Protection is generally between 45 to 60 days, but the copper may need reapplication at a half rate if there has been greater than average rainfall.”
  • “Other products that can work well in the later season are Orondis Ultra (FRAC codes 40+49) and Revis (FRAC code 40). See rates and usage patterns in the Florida Citrus Production Guide brown rot chapter. These products work well in the late season and protect fruit for at least 30 days. It is important to rotate fungicide modes of action between any root rot/foot rot treatments and brown rot treatments.”

Phytophthora and Brown Rot

The article added information on the relationship between phytophthora and brown rot:

“The phytophthora diseases are all related. The phytophthora root propagule count is indirectly related to brown rot. But if your counts are high, you are more likely to have brown rot on cultivars at color break. Dropped fruit attract zoospores which infect and sporulate quickly. The new sporangia and zoospores then get splashed into the canopy.

As a reminder, both Phytophthora palmivora and P. nicotianae can cause brown rot. P. palmivora is a greater concern for the disease because of its ability to splash from fruit to fruit, causing infection all the way to the top of the canopy. However, P. nicotianae can be very destructive in unskirted trees, although infection stops at approximately 3 feet above the soil.”

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