Recap of January 2026 First Friday with Florida First Detector

In this month, we explored the fascinating, and sometimes frustrating, world of plant pathogens. Simply put, a pathogen is any organism that causes disease. For plants, these culprits can include fungi, bacteria, viruses, nematodes, and more.

When diagnosing plant health issues, it’s important to distinguish between signs and symptoms. Symptoms are the plant’s response to the disease, such as yellowing leaves, necrotic spots, wilting, or dieback. Signs are the physical evidence of the pathogen itself. This includes things like fungal spores, fruiting bodies, or bacterial ooze. Fungi are multicellular or unicellular organisms that reproduce by spores and often cause diseases like rots, wilts, and blights. Bacteria are microscopic, single-celled organisms that multiply rapidly and often enter plants through wounds or natural openings, causing issues like leaf spots and wilts. Viruses are much smaller than fungi or bacteria and require a living host to reproduce. They typically spread through insect vectors or mechanical damage and cause systemic symptoms like mosaic patterns or stunted growth. Nematodes are microscopic roundworms that live in soil and feed on plant roots, leading to root galls, stunting, and reduced nutrient uptake.

While the pathogen (aka the fungi, bacteria, virus, etc.) is the cause, the disease is the effect. Plant diseases are the way the plant suffers as a result. During the webinar, we highlighted several impactful plant pathogens and diseases, including Boxwood blight, sudden oak death, citrus greening, Ralstonia solanacearum R3B2, lethal bronzing, lethal yellowing, rose rosette virus, citrus yellow vein clearing virus, and red ring disease. These diseases have caused significant challenges for agriculture and horticulture industries. Fortunately, some of the most concerning pathogens like red ring nematode, Ralstonia solanacearum R3B2, Phytophthora ramorum, and citrus yellow vein clearing virus are not currently found in Florida.

Diagnosing plant pathogens isn’t always straightforward. Many require laboratory testing for confirmation. If you notice unusual symptoms, especially something unfamiliar, don’t guess! Contact your local county Extension office. They can guide you through sample submission and provide accurate identification and management recommendations.