Frequency-Domain Sensors (FDS) 
A method used by a soil moisture meter to measure soil moisture content. It measures the frequency from a sensor within the soil which is connected to an oscilloscope. The higher the soil moisture, the higher the reading (called the dielectric constant).
There are two types of sensor used:
1. Capacitance sensor (Frequency Domain Reflectometry), and
2. Electrical impedance sensor (Coaxial Impedance Dielectric Reflectometry).
Frost
The formation of ice crystals on leaves of grasses and plants. The ground or surface temperature will be at 0°C or below for frost to form. Where a lawn or sports turf surface has frost present then it is best to not walk on the area until the frost has gone from the leaves as well as within the soil. If grass is walked on during a hard frost then it is possible to crush the grass leaves, turning then a blackish colour. In addition, if the frost is thawing then the point where the thawing surface interacts with a still icy lower layer will be weak and if walked on this can typically result in shearing or tearing of roots.
Frost Tolerance
The ability of a plant to resist damage to itself, by being able to survive and adequately recover, when exposed to frost and ice formation within and between its plant cells.
Fructose
A simple carbohydrate (sugar) product of photosynthesis.
Fulvic Acid
The part of humus which is soluble in water under all pH conditions. It is typically coloured light yellow to light brown and is produced in the earlier stages of humification.
Fungi
A taxonomic Kingdom of heterotrophic organisms which reproduce by spores or mycelial fragmentation. The fruiting body of a fungi is a mushroom, toadstool, puffball, or similar; whilst underground thread like growths are called hyphae, collectively known as mycelium. Most turf diseases are caused by fungi. There are approximately 12,000 species of fungi in the British Isles.
The two main divisions, or phyla, or fungi in the UK are Ascomycota and Basidiomycota.
Fungi Lifecycles
The actual lifecycle of a pathogenic fungi will vary; however, the following lifecycle helps to understand the general approach taken by many fungi.
• Stage 1: Spore germination on surface of plant.
• Stage 2: Penetration of plant by spores and hyphae, through openings (e.g. stomata), damaged epidermal tissue (e.g. via cut cells from mown leaves).
• Stage 3: Parasitic hyphae and mycelium grow within plant tissue, infecting it and extracting nutrients from its cells, typically killing the infected part of the plant, the severity of which will depend on how far the mycelium and
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Genera
Genotype
The genetic makeup of a plant, which is inherited from its parents.
Genus
A taxonomic category that is used to group organisms. A Genus is grouped from similar Species. Similar Genera are in turn grouped into a Family.