A nematicide is a type of chemical pesticide used to kill parasitic nematodes. nematode Nematodes are unsegmented, bilaterally symmetric and triploblastic protostomes with a complete digestive system. nitrogen oxides noninfectious disease nonpathogenic (syn. avirulent) nonpersistent transmission (syn. stylet-borne transmission) nonseptate O obligate parasite (syn. biotroph) occlusion oedema (also edema; syn. intumescence) oligogenic resistance oogonium (pl. oogonia) An oogonium is a female gametogonium. oomycetes (adj. oomycetous) oospore ooze ostiole (adj. ostiolate) overwinter P pandemic papilla paragynous parasexualism parasite (adj. parasitic) parasitism parthenogenesis (adj. parthenogenetic) partial resistance pasteurization pathogen (adj. pathogenic) pathogenesis-related (PR) proteins pathogenicity pathology pathotype pathovar (abbr. pv.) penetration penetration peg (syn. infection peg) perfect (see teleomorph) perithecium (pl. perithecia) peritrichate persistent transmission (syn. circulative transmission) pest pesticide phenological synchrony phenotype phloem necrosis Phycomycete phyllody phylloplane-competent physiogenic disease phytoalexin phytopathogenic phytopathology (syn. plant pathology) phytoplasma (syn. mycoplasmalike organism, MLO) phytosanitary certificate phytotoxic plant pathology (syn. phytopathology) plasmodiophoromycetes plasmodium (pl. plasmodia) polycyclic polyetic polygenic resistance (syn. multigenic resistance) polymorphism polyprotein powdery mildew predispose (n. predisposition) primary inoculum (syn. initial inoculum) proinhibitin prokaryote promycelium (pl. promycelia) propagative transmission (syn. circulative propagative transmission) propagule protectant protectant fungicide (syn. contact fungicide) pseudothecium (pl. pseudothecia) Puccinia pathway pustule pv. (abbr. for pathovar) pycnidiospore pycnium (pl. pycnia; syn. spermagonium) Q qualitative resistance quantitative resistance quarantine quiescent quiescent dormant or inactive quorum sensing R race race non-specific resistance (syn. general resistance, horizontal resistance) receptive hypha reniform resinosis resistant (n. resistance) rhizomorph rhizosphere rhizosphere-competent ringspot rosette rot roundworm rugose russet rust S sanitation sap transmission saprobe (syn. saprotroph) saprotroph A saprotroph (or saprobe) is an organism that obtains its nutrients from non-living organic matter, usually dead and decaying plant or animal matter, by absorbing soluble organic compounds. scab scald sclerenchyma (adj. sclerenchymatous) sclerotium (pl. sclerotia) A sclerotium is a compact mass of hardened mycelium (as an ergot) stored with reserve food material that in some higher fungi becomes detached and remains dormant until a favorable opportunity for growth occurs. scorch secondary infection secondary inoculum secondary metabolite secondary organism seed treatment seedborne selective medium septate serrate sessile seta (pl. setae) sexual spore sexually compatible shot-hole sign single gene resistance (syn. monogenic resistance) slime molds (syn. Myxomycetes) smut soft rot soil drench soilborne soil pasteurization soil sterilization solarization sooty mold sorus (pl. sori) sp. (abbr. for species; pl. spp.) species specific resistance (syn. vertical resistance) spermagonium (pl. spermagonia; syn. pycnium for rust fungi) spermatium (pl. spermatia; syn. pycniospore for rust