This is a glossary of some of the terms used in phytopathology. Phytopathology is the study of plant diseases. It is a multi-disciplinary science since prerequisites for disease development are the presence of a susceptible host species, a pathogen and the appropriate environmental conditions. This is known as the disease triangle. Because of this interaction, the terminology used in phytopathology often comes from other disciplines including those dealing with the host species ( botany / plant science, plant physiology), the pathogen (bacteriology, mycology, nematology, virology), the environment and disease management practices (agronomy, soil science, meteorology, environmental science, ecology, plant breeding, pesticides, entomology), and areas of study that apply to both the host and pathogen (molecular biology, genetics, molecular genetics). The result is that most phytopathological glossary include terms from these other disciplines in addition to terms (disease incidence, horizontal resistance, gene-for-gene relationship, blast, scab and so on) that are specific to, or which have a unique meaning in phytopathology. This glossary is no exception. However, for the sake of brevity, it has, for the most part, restricted terms from other disciplines to those that pertain to the pathogen. At some point, these terms should be moved to other glossaries (e.g. glossary of mycology, glossary of nematology, and so on). A abiotic Disease not caused by living organisms acceptable daily intake acervulus (pl. acervuli) The acervulus is an erumpent, cushionlike fruiting body bearing conidiophores, conidia, and sometimes setae. It is distinguished from a stroma in not having a peridium or covering of fungal tissue of any kind. acid precipitation acid rain acropetal Actinomycetes The Actinobacteria or Actinomycetes are a group of Gram-positive bacteria. acute acute toxicity aeciospore aecium aflatoxin agar aggressiveness air pollution alkaloids allele allelopathy alternate host alternative hosts alternation of generations amphid amphigynous amphimixis amphimobile anaerobic anamorph (adj. anamorphic; syn. imperfect state) anastomosis (pl. anastomoses) anthracnoes antibiotic antibody antigen antiseptic apothecium The apothecium is an open, cuplike, or saucer-shaped sexual fungal fruiting body (ascocarp) containing asci. antiseptic appressorium (pl. appressoria) arbuscular mycorrhiza (abbr. AM; syn. endomycorrhiza) arbuscule ascocarp (syn. ascoma) ascogenous ascogonium (pl. ascogonia) ascoma (pl. ascomata; syn. ascocarp) Ascomycetes asci ascospore ascostroma (pl. ascostromata) ascus (pl. asci) aseptate asexual asexual reproduction atrophy AUDPC (abbr. for Area Under Disease Progress Curve) autotroph avirulence (avr) gene avirulent (syn. nonpathogenic) axenic autoecious B bacilliform bacterial streaming bactericide bacteriocin bacteriophage bacterium (pl. bacteria) bactericide basal knob (syn. stylet knob) basidiocarp (syn. basidioma)