Read recommendations on Phytophthora and root health from UF/IFAS experts for Florida citrus growers.

In our latest column in Central Florida Ag News, we shared that the 2020-2021 Florida Citrus Production Guide maintains, “Historically, the most damaging root pathogens in citrus have been Phytophthora.” The pathogen causes cause root, crown, and foot rot, and ultimately leads to the decline and death of the tree. Unfortunately, citrus greening, caused by the Candidatus Liberibacter asiaticus (CLas) bacteria, also causes significant damage to a citrus tree’s root system. See the recommendations from experts when it comes to Phytophthora and root health.

A Focus on Phytophthora and Root Health

Phytophthora is spread by water molds, and it is found everywhere. It travels through water and infects roots, causing root, crown, and foot rot below the soil line. Recommendations for guarding citrus tree roots from Phytophthora, include both cultural practices and chemical control methods, according to UF/IFAS scientists and authors of the 2020–2021 Florida Citrus Production Guide: Phytophthora Foot Rot, Crown Rot, and Root Rot, Evan Johnson and Megan Dewdney.

Recommendations include:

Disease Exclusion Practices. Know your grove’s history. For new groves that have never been planted with citrus before, it’s unlikely that Phytophthora nicotianae would be present. In groves with a history of Phytophthora foot rot, plant citrus trees on tolerant rootstocks, such as Swingle citrumelo.

Irrigation Controls. Since Phytophthora-causing molds thrive in wet environments, it’s important to utilize precision irrigation. Overwatering and the prolonged wetting of tree trunks allows phytophthora populations to build up in the soil, increasing the chances of infection.

Chemical Controls. Fungicides should be used in a preventative manner on young, susceptible rootstocks. On young, tolerant rootstocks, fungicides should be used if foot rot lesions develop.

Pest Management. Pests such as fire ants and Citrus Root Weevils have been shown to cause damage to citrus trees, creating lesions for Phytophthora to enter and infect the tree.

Griffin Fertilizer is committed to helping both growers and ranchers make sound agronomic and economic decisions in order to maximize the health of their grove and pasture. As a full-service custom dry & liquid fertilizer blender and crop protection product distributor, we will continue our mission to further advance Florida agriculture. For questions or concerns about your farm or pasture, contact us and one of our team will be in touch.