I have moved into a new build house and the lawn already has "spikey grass" parts consistently over the lawn. Around 60 patches in an area of 50 sq metres. In places, around 1 inch taller than the rest of the grass. These show up as light Green when taking a photo at night (with flash on) and are a different texture.
The turf has been down around 4 weeks now
There are a few grasses that stand head and shoulders above the others when in a grass plot, among them are barnyard grass (Echinochloa crus-galli) and orchard grass (Dactylis glomerata), both widely distributed over the earth surface. Examine the base of the main grass shoots - if flattened then it is orchard grass. Barnyard grass is vigorous and will persist from clumps quite obstinately.
Since you have had sod/turf laid there is a possibility that what you are seeing is volunteer growth from the native ground under the turf. The sod (usually very carefully and professionally cultivated with specific seed but inevitably containing some impurities) will have been carefully watered to ensure quick establishment and this of course will favour the native grasses that have enough energy to push through the turf laid over the top and particularly emerge through the cracks between the turf pieces. See if the spiky bits tend to follow a rectangular pattern which would indicate the turf outlines.
Control is difficult. They tend to survive very well in drought; at such times regular mowing is set aside and this allows these grasses to flourish as the competition dies down. Spot mowing helps.
