plantpathogen

A plant pathogen is any organism that causes disease in plants. This broad category includes fungi, oomycetes, bacteria, viruses, nematodes, and parasitic plants. Plant pathogens can infect crops, fruit trees, and ornamental species, leading to yield losses, wasting of resources, and reduced quality. They may attack roots, stems, leaves, fruits, or the vascular system and can spread through air, water, soil, seeds, or insect or other animal vectors.

Major groups of plant pathogens include fungi (such as mildews, rusts, and blights), oomycetes (like Phytophthora and Pythium), bacteria (for example Xanthomonas and Pseudomonas), viruses (such as tobamoviruses and geminiviruses), nematodes (root-knot and cyst nematodes), and parasitic plants (such as Cuscuta). Each group has distinct life cycles, infection strategies, and environmental requirements.

Disease development typically depends on host susceptibility and environmental conditions, including temperature, humidity, and plant growth stage. Pathogens form structures such as spores or oospores or rely on vectors to move between hosts. Infection and colonization lead to visible symptoms (lesions, chlorosis, wilting, or stunted growth) and can compromise plant function or yield. Some infections remain latent or asymptomatic until conditions worsen.

Detection and diagnosis rely on symptom observation complemented by laboratory methods. Microscopy, culture, serology, and molecular techniques (PCR, qPCR, sequencing) aid in identifying the causal agent and informing management.

Management emphasizes prevention and integrated approaches. Cultural measures (crop rotation, sanitation, resistant varieties), chemical controls (where appropriate), biological controls (beneficial microbes), seed treatments, and quarantine help reduce risk and limit spread. Ongoing research in plant pathology targets understanding host–pathogen interactions and improving durable resistance.