Section 7: Managing farm hygiene
Vehicles are major sources
of new weed infestations.
Photo: A. Storrie
One area of weed management that many farmers fail to implement is the stopping of unwanted seeds and propagules (corms, tubers etc.) coming onto, or being spread within the property. This has led to the introduction of a new species of weed, or one with glyphosate or paraquat resistance from external or internal sources.
‘Risk aware’ growers can implement strategies to reduce and avoid unnecessary introduction and spread of weeds.
Weed importation and spread can be impeded at several critical points, namely:
- Sowing of the seed
- Fencelines and non-cropped areas in cropping paddocks (e.g. water courses)
- Machinery and vehicle usage
- Stock feed and livestock movement.
- In fields following floods and inundation
A well-managed on-farm hygiene strategy will address each of these elements.
IWM manual on managing farm hygiene
7.2 Sow weed-free seed
Weed seed is regularly spread around and between farms as a contaminant of sowing seed. Seed for sowing is commonly grower-saved and more often than not contaminated with weed seeds, frequently at very high levels. Various ‘seed-box’ surveys have found farmers sowing weeds with less than a quarter of farmers surveyed sowing weed-free seed. On average, ungraded seed had 25 times more foreign seeds than graded seed.
To avoid these problems follow the following points:
- Know the weed status of any farm from which you buy seed.
- Plan seed purchases ahead of time and inspect the paddock where the seed is being grown.
- Obtain a sample of the seed and have it analysed for both weed seed contamination and germination.
- Determine the herbicide resistance status of weeds present on the source farm and paddock, and avoid purchasing seed from paddocks with known resistance.
- Grade seed to reduce weed numbers.
IWM manual on sowing weed-free seed
7.3 Manage weeds in non-crop areas
Flaxleaf fleabane along this fence
will easily spread into
Photo: A. Storrie
Weed infestations often commence in non-crop areas (e.g. around buildings, along roadsides, along fencelines, around trees). Controlling these initial populations will prevent weeds from spreading to other parts of the property. These areas have become primary sources of glyphosate resistant weeds which then spread into paddocks. This is particularly important for weeds with wind-blown seed such as fleabane and sowthistle.
Weeds along fencelines, paddock edges and non-crop areas of crop paddocks can be controlled by a combination of knockdown herbicides, hay or silage cutting, and/or cultivation. Unlike other activities, timing for fenceline weed control is reasonably flexible with a wide window of opportunity, although control should be carried out before seed is viable.
IWM manual on managing weeds in non-crop areas
7.4 Clean farm machinery and vehicles
Machinery and vehicles are major sources for the introduction of new weeds. Earth moving equipment, harvesters, balers and slashers are particular problems.
Ensure machinery and vehicles have been cleaned prior to entry on the farm, or cleaned at a specially designed wash station. Within the farm, harvest from cleanest to dirtiest paddock to minimise the spread of weed seeds. Where breakdowns require in field repair, mark the position with a GPS and diary to check for weed germinations.
IWM manual on clean farm machinery and vehicles
7.5 Livestock feeding and movement
Weeds can be introduced in stock feed and in livestock over long distances, particularly during droughts. Ensure you know the fodder source. New or stock returning from adjustment need to be kept in a holding paddock for seven days to enable the bulk of seed in their guts to be excreted.
IWM manual on managing livestock feeding and movement
7.6 Monitor paddocks following flood inundation
This creekline is infested with
annual ryegrass and a range
of other weeds. During
the next flood these seeds
will spread across previously
Photo: A. Storrie
Floods and inundation of fields are a common source of new weed infestations through the transport of seeds and vegetative propagules such as stolons, rhizomes and tubers.
Effective monitoring to identify new weed incursions and patches is needed. Hand roguing a few plants every year can help when weed numbers are very low, even on very large properties.
IWM manual on managing paddocks following flood
7.8 Further information
Tactic Group 5, Part 4 of the Integrated Weed Management Manual: farm hygiene
GRDC video links
GRDC webinar on managing weeds on fencelines (2014)
Weed Seed Bank Destruction - Farm Hygiene and Weed Management (2013)
Farm hygiene tutorial explains how to limit the movement of weed seed from different parts of the farm or from outside the farm. Tactics for managing weeds on fence lines, contamination of paddocks from hay and livestock. Tactics for managing weed blow-out situations - not allowing weed escapes to set seed.
Risk of weed movement through vehicles, plant and equipment: results from a Victorian study (2006)
Cotton CRC - Farm hygiene for Disease and Weed Control - Come Clean Go Clean (2003)
Grain farm biosecurity
Seed box survey of field crops in Victoria during 1996 and 1997 (2002)
Weed seed contamination in cereal and pulse crops (2002)