PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
CULTURAL
METHODS
(contd)
MULCHES.
Suppress annual weeds by excluding light needed for growth.
Are not very effective against perennial weeds, eg tap rooted dandelion,
stolons of couch grass. Nutgrass may grow through polythene film < 0.2 mm thick.
Weed mat may be laid beneath mulches to prevent roots of perennial weeds which do
develop in the mulch, from penetrating deep into the soil, making removal easier.
Must be porous to allow water to seep through and air to circulate, of the correct
depth, and aged and/or composted before use. Preferably lay when soil is moist.
Before applying mulch, remove or spot spray weeds, especially perennials
weeds.
Mulches protect soil from wind and sun, reducing losses from evaporation.
– Reduces soil temperature fluctuation, eg by up to 5 o C in summer, in winter mulches
shade soil from spring sunshine, slowing spring crop growth.
– Protect surface and shallow feeder roots, increase beneficial soil microbes.
– Coarse mulches control windblown weed seeds better than fine mulches.
– Provide cleaner and easier harvesting of strawberries and ginger roots, etc.
Mulches may be:
– Inorganic, eg woven plastic weed mats, blue metal, crushed brick, river gravel
mostly need to be applied to a depth of 9-10 cm to provide adequate weed control.
– Organic, eg bark, wood chips, sawdust, straw, hay, compost, pine needles, leaf
litter. Pre-cut disks of breathable durable recyclable polypropylene can be placed
around new or existing tress and shrubs, posts and in planters. Paper (pellets, sheets,
rolls), cardboard, seaweed, wool, etc.
– Mulches provide shelter for termites, slaters, etc. They can be a fire hazard.
SANITATION
,
.
CAREFUL MANAGEMENT.
Sanitation may overlap with Physical and Mechanical Methods (page 438).
Sanitation is important at all levels of quarantine to prevent spread of weeds, eg
washdown facilities in the NT for barges going to the Tiwi Islands. Cleaning
mowers, slashers, vehicles and earthmoving equipment after use in weedy areas
before using in clean areas to reduce spread of weeds such as Chilean needlegrass.
Suppress weeds by persistently preventing seed set and spread when weed
populations are low as well as suppressing outbreaks of new weeds as soon as they
occur by cultivation, mowing or herbicides, etc.
For greenhouses maintaining a 3–6 meter weed-free barrier outside the
greenhouse helps to minimize weed seeds entering via vents and doors.
– Screening vents prevent windblown seeds. Porous concrete walkways and geotextile
fibre mats under benches help prevent establishment of weeds.
– Keep potting mixes and ingredients covered.
– Pots may be isolated from direct soil contact by use of screenings (8–10 cm of
18–20 mm gravel or blue metal) and concrete paths.
– Nursery accreditation schemes specify weed control measures.
Disposal of garden waste, weeds.
– There are still many species in gardens that could naturalize in Australia.
– Do not dump garden waste in bushland, over fences or cliffs or into creeks.
– Recycle waste through local council or take it to the local tip.
– Cover trailers when taking garden waste to the tip so seeds and cuttings do not fall
off and invade roadside bushland. Double bag garden waste (place in one bag, knot,
then place in another bag to stop seeds being spread en route, compost garden waste
at home or take to a recycling site.
– Composting garden waste at 60 o C for 30 minutes will not kill most weed seeds.
Properly carried out composting of bark will kill most weed seeds and plant parts.
Hand pulling and digging out annual or herbaceous perennial weeds before
they set seed, is suited for small shallow rooted weeds and small infestations.
Easiest when soil is soft and moist. A mattock is useful for digging out many weed
species. Hand weeding is laborious and can be an ineffective means of selectively
removing weeds in large areas. Remember the soil disturbance will move more
weed seeds into the germination zone.
Cutting woody weeds. Use secateurs, hand saw or chainsaw is often used for
controlling woody weeds and for some species that do not re-shoot, can be done
without need for herbicides, eg wattles, pines (pages 467-468).
Control weeds on non-crop areas around the nursery, farm, etc before they
set seed. Immediate removal of undesirable weeds or strategic spot spraying can
halt spread of weeds and reduce or eliminate use of herbicides.
Prevent spread especially when moving soil and plant material through the
landscape.
Some systems allow for the collection of weed seeds at harvest.
434 Weeds - Integrated Weed Management