The diseases have been categorized as patches (cause dead spots or patches in the lawn), rings (cause rings of dead or affected grass), or leaf blight (affect individual blades of grass, often over a wide area and no distinct patch or ring pattern may be noticeable).
PVR, abbreviation for pulmonary vascular resistance. To measure changes in blood vessel size or changes in gas volume in the lungs to assist in diagnosing diseases such as deep vein thrombosis (DVT), chronic obstructive pulmonary disease (COPD), and some peripheral vascular disorders. Veins, arteries, and lungs. None.
Polyvinyl alcohol (PVA), a colourless, water-soluble synthetic resin employed principally in the treating of textiles and paper. 1  PVA is unique among polymers (chemical compounds made up of large, multiple-unit molecules) in that it is not built up in polymerization reactions from single-unit precursor molecules known as monomers.