A renovation programme involves a series of procedures that restores
the lawn to a good condition. In early spring, cut the turf to 5
cm and remove the clippings. Reduce the cutting height incrementally
at subsequent mowings until the required height is reached. Then,
fertilise the lawn, and apply a herbicide two weeks later to control
weeds. Reseed bare or uneven patches one to two weeks after herbicide
application. At the beginning of autumn, aerate, top-dress with
sand-soil mix, and fertilise the lawn, in that order of events.
Follow a regular maintenance programme thereafter (see Table 1).
Edges that have been damaged in small areas can be repaired by
cutting the turf with an edger against a plank of wood. Slice under
the section of turf with a spade (Figure 1) and slide it towards
the lawn edge until the damaged area is outside the lawn. Trim off
the damaged part to align the turf with the existing lawn edge.
Re-grass the resulting gap in the turf within the lawn by adding
a little soil and reseeding with a grass mixture.
Cut a cross through the turf on an affected area, and peel back
the cut turf (Figure 2). To level a hollow, fork over the soil beneath
and fill in with topsoil, and firm the ground. For a hump, remove
the excess soil until the ground is level, fold back the cut turf
and tamp it down with the back of a rake, before top-dressing and
Figure 2: Levelling in a hollow or hump.
Annual maintenance programme
The annual maintenance programme is summarised in Table 1.
Turf diseases in hot humid regions include brown patch, dollar
spot, fairy rings, Fusarium patch and red thread. Fusarium patch
may also occur in cold regions, even under frost or snow. Other
disease-like problems occur in waterlogged areas.
Algae and lichens
Algae and lichens may be prominent, particularly in poorly drained
and aerated or compacted soils. Patches of green to greenish-black,
slimy, slippery algae and gelatinous lichens, or dog lichens, which
are recognised by groups of curled leafy growths that are greenish-black
on the upper surface and creamy-white on the lower surface, can
be controlled by removing the thatch, aerating the lawn, and/or
installing drainage pipes. Trees or shrubs that provide excessive
shade over the lawn should be trimmed as well.
Dollar spot is a common fungal disease of turf grasses throughout
the growing season. There are at least two strains of the dollar
spot fungus in the genera Moellerodiscus or Lanzia
that cause disease during cool and warm seasons. The fungus initially
appears as a 3-8 cm circular to irregular straw-coloured patches
that eventually darken and coalesce to form larger blighted areas.
Individual blades typically have straw-coloured or bleached white
lesions across the blade width, which causes the blade to be pinched
in the middle and gives the appearance of an hourglass-shaped lesion.
The lesions are also commonly bordered above and below by dark brown
bands and the blades also show dieback from the tip. When the fungus
is active and moisture is present during the early morning hours
a cobwebby growth can sometimes be seen growing on the grass blades.
The disease affects most turfgrasses, but turf containing fine-leaves
bents and creeping fescues are susceptible, while tall fescue appears
resistant. Turfgrasses grown under low fertility conditions appear
to be the most susceptible to dollar spot. Drought also increases
susceptibility to disease along with thick thatch and compacted
soil. Favourable conditions for disease development include warm
humid weather and cool nights with heavy dew formation.
The fungus favours heavy or compacted soils with a high pH, such
as alkaline soils or those treated with alime. It appears in mild
An application of nitrogen fertiliser at the 3 g nitrogen/m²
will stimulate foliar growth at a rate faster than the fungus can
injure the blades. Lessen the severity of the disease by alleviating
drought stress with regular watering, and avoid thatch build-up
and compaction of the soil. Over-seed with resistant cultivars from
the recommended turf grass cultivar lists. Improve soil aeration
and remove thatch. Reduce soil pH with sulfur or acidic fertilisers
such as ammonium sulfate. Apply cyproconazole, chlorothalonil or
iprodione (Table 5).
Slime moulds are recognised by clusters of beige, orange or white
fruiting bodies that smother individual blades of grass. The spores
that are released give the slime mould a grey appearance. The grass
looks unsightly but is not harmed. The condition is particularly
common in late spring and again in early autumn, when rainfall is
high. The slime can be washed of the grass using a high-pressure
hose directed onto the affected areas.
Snow mould/Fusarium patch
Lawns that contain a high proportion of annual meadow grass (Poa
annua) are particularly susceptible. Patches of grass become
yellow and die, often coalescing to form large areas. In autumn
when conditions are damp and night temperatures are low, a white
fungal growth appears, causing the grass blades to stick together,
giving affected areas a slimy look. Control options include regularly
aerating and scarifying the turf. Avoid using high-nitrogen fertilisers
in late summer to early autumn. Treat affected turf with chlorothalonil
or iprodione (Table 2).
Fine-grassed lawns are particularly affected by red thread. Very
small, pale-pink to red gelatinous, branching threads of fungus
develop on small patches of grass, which later become bleached of
colour. The fungus very rarely kills the lawn. The fungus is common
after heavy rain, and when the soil is nitrogen deficient or poorly
aerated. Aerating, scarifying and fertilising the turf will control
the disease. Chemical control should not be necessary on a well-maintained
lawn. However, if the infestation is severe, apply cyproconazole,
chlorothalonil or iprodione for effective control.
Toadstools are fungal fruiting bodies that sometimes develop in
distinct circles (‘fairy rings’), often on buried woody
material. Most cause little damage to turf, but fairy rings are
harmful and disfiguring to it. Two circles of very lush, green grass
form, one within the other, and may be 2-5 m in diameter. The grass
in between the circles dies, killed by toxins released by the fungal
mycelia between the rings. Toadstools then emerge on the outer part
of this middle zone. A white, fungal growth permeates the soil in
the area of the ring. The fungi are spread to new sites by wind-borne
Control consists of brushing off the toadstools when they first
appear, before their spores are produced. Remove any fungi on buried
wood. The fairy rings cannot be controlled using fungicides, although
watering with a wetting agent may make the soil less susceptible
to fungal growths.
Perennial ryegrass is not affected by autumn Fusarium patch disease,
which badly affects browntop. Ryegrass can be affected by red thread
disease from autumn to spring, particularly in sheltered and shaded
positions. Crown rust can also affect certain varieties, but most
appear to be resistant to it now. For both diseases an application
of nitrogen fertiliser once temperatures are above 10°C is usually
Table 2: Fungicides registered in 2003 for control of diseases
in cotula, dichondra, fine turf, greens and lawn turfs.
Thanks to Bill Walmsley, New Zealand Sports Turf Institute, for
his article which was abridged for the section ‘Perennial
Ryegrass for Lawns and Turf’, and Sam Wakelin for the drawings
in Figure 1, Figure 2 and 3. Thanks also to Robert Lamberts for
the photographs of weeds.