PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Weeds in turf
Commercial turf is an industry in itself.
Weed types
Annual and perennial broadleaved and grass weeds
need to be controlled during turf preparation,
establishment and maintenance. Winter grass (Poa
annua) is the most written about weed affecting
commercial turf.
Impacts
Weed impacts in turf are well known. In commercial
turf water and nutrients are used up. Playing surfaces
become uneven. In home gardens, flowering heads
tower above the turf, flat growing weeds smother
surrounding turf, etc.
Weed biology
‘Overwintering’. Weed seed, some of which is in
the seedbank in the soil, rhizomes, etc.
Spread. Seed by wind and water. By growth of
stolons on the surface of the soil. Bulbs, stem pieces
by cultivation. In soil deliveries, manure, compost,
containers as seed, rhizomes, cut-up root pieces,
bulbs, top dressing products.
Conditions favouring. Weeds may colonize bare
areas in turf due to heavy traffic, environmental stress
or chemical applications to existing weeds.
Commercial contractors in low maintenance areas
have a tendency to ‘scalp’ grassed areas. Poor
drainage, hollow coring and scarifying at a time
Management (IWM)
Are you a commercial grower or home gardener?
1. Prepare a plan. Access a weed management plan for
your turf species involving site preparation, turf
establishment and maintenance.
2. Crop, region. Recognize variations.
3. Identification of existing or likely future weed(s)
must be confirmed. Recognize mown weeds, consult a
diagnostic service if necessary (page xiv). Understand
life cycles, spread, etc. habitat conditions, etc.
4. Monitor weed(s) and/or impacts and record results
(page 429).
5. Threshold. Have any thresholds been established? If
so, are they, playing requirements and/or aesthetic?
6. Action. Take appropriate action when any threshold is
reached.
7. Evaluation. Review IWM program to see how well it
worked. Recommend improvements if needed.
Control methods
Do not introduce weed seeds, rhizomes or cut up root
pieces in soil deliveries for turf establishment or top
dressing. If using herbicides always check the
label for the type of turf they can be used on.
Site preparation. Perennial weeds should be
controlled either by hand weeding or by spraying,
when weeds are actively growing, with Roundup
(glyphosate), at least 2 weeks prior to cultivation to
prepare the seed or turf bed. Once the soil is prepared
for sowing or turfing, if any weeds germinate during
this period they should be destroyed either by hand
weeding, shallow cultivation or with herbicides. In
commercial turf, sterilization of the seedbed may be
warranted, or complete removal of infested soil.
Turf maintenance. Weeds should not be a problem
in dense well managed commercial turf or home
garden lawn as the competition from grass should not
allow weeds to gain a foothold. In a home garden,
weeds can be removed by hand or dug out; many
broad leaved weeds can be controlled to some extent
by ‘Lawn Sand’ (page 454) or herbicides. Some
weeds in turf may be mowed out, eg chickweed.
Table 80. Weeds in turf – Some herbicides (mostly for commercial growers).
What to use?
SITE PREPARATION & TURF ESTABLISHMENT
Site preparation
Group M, eg Roundup (glyphosate)
Newly established turf is sensitive to recommended rates of
herbicides. Do not apply herbicides to turf < 3 months of age, do not
mow for 3 days before or after spraying, or fertilize for 2 weeks before or
after spraying, unless label directions state otherwise.
TURF MAINTENANCE
Broadleaved weeds in turf
Post-emergents, eg
Group I, eg Kleenlawn , various (dicamba + MCPA) – hormone
herbicides
Pre-emergents, eg
Group D, eg Dacthal (chlorthal)
Group G, eg Ronstar Turf & Ornamental Herbicide (oxadiazon)
Grass weeds in turf. Commercial turf only
Post-emergents, eg
Group A, eg Hoelawn (diclofop-methyl)
Group I, eg Drive (quinclorac)
Pre-emergents, eg
Group D, eg Dacthal (chlorthal), Pre-M (pendimethalin/
fertilizer), Dimension (dithiopyr)
Group G, eg Ronstar Turf & Ornamental Herbicide (oxadiazon)
Group J, eg Tramat (ethofumesate)
SPOT SPRAYING, ROPE-WICK, WEEDING BRUSH
Group M, eg Roundup (glyphosate) Non-selective
When and how to use?
At least 2 weeks prior to cultivation to prepare the seed or
turf bed, annual and perennial weeds should be controlled
either by hand weeding or by spraying when weeds are
actively growing, with glyphosate. Once the soil is prepared
for sowing or turfing, if any weeds germinate during this
period they can be destroyed either by hand weeding,
shallow cultivation or herbicide.
Hormone herbicide injury to ash tree due to drift
from a hose-jar application to a home garden lawn
Treat weed clumps with a weeding-brush or spot spray.
462 Weeds - Examples of weed situations