Integrated pest management for weeds and crop diseases

Integrated pest management (IPM) means combining several control methods across the season so that no single tool carries the whole load. This guide is for growers who manage their own weeds and crop diseases. It explains how the approach works, what the main building blocks are and where to find Australian guidance for your crop and region.

The principles apply across broadacre cropping and horticulture. The detail, including which weeds and diseases matter, which varieties resist them and which products are registered, depends on your crop, district and state.

What integrated pest management means for weeds and diseases

An integrated approach starts by asking where a problem comes from and when the crop is most exposed, then uses several measures to cut the risk at different points. NSW DPIRD’s guidance on integrated disease management for greenhouse growers describes it this way: identify infection risks first, then let regular crop checks decide whether and when to act. The same logic applies in the paddock and to weeds.

In practice, an integrated plan draws on four kinds of tactics:

• Preventive: keeping weed seeds and disease out, and removing the plants that carry problems between seasons.
• Cultural: rotation, variety choice, sowing decisions and crop competition.
• Physical and mechanical: cultivation, harvest weed seed control and removing infected material.
• Chemical: herbicides and fungicides, used as one part of the plan rather than the whole of it.

Why relying on one control method stops working

Weeds and pathogens adapt to whatever pressure they meet most often. When the same herbicide or fungicide group is used again and again, resistant individuals survive and multiply until that product stops doing its job. GRDC reported in 2020 that its surveys were finding herbicide resistance on the rise.

The cost is significant. GRDC’s Integrated Weed Management Manual, published in 2019, estimates that weeds cost Australian grain growers about $3.3 billion a year. Each chemical group that stops working leaves fewer options for the problems that remain.

CropLife Australia’s 2025 announcement of its resistance management strategies makes the same point for herbicides, fungicides and insecticides. It warns against leaning heavily on single-site chemistries and says chemical use should sit alongside other agronomic practices.

The building blocks of an integrated plan

Prevention and farm hygiene

The cheapest weed or disease to manage is one that never arrives. Agriculture Victoria’s Come Clean, Go Clean advice notes that vehicles, machinery and quad bikes can carry pests, diseases and weeds between paddocks and properties. Cleaning soil and plant material off equipment before it moves, and asking visitors to do the same, reduces that risk.

In horticulture, clean planting material matters just as much. NSW DPIRD advises greenhouse growers to inspect seedlings when they arrive and keep them separate for a period before planting.

In grain systems, a key preventive step is breaking the green bridge. This is the volunteer crop plants and grass weeds that keep diseases and some pests alive between one crop and the next. GRDC’s GroundCover article on green bridge control explains that removing these plants well before sowing delays rust outbreaks, and that the benefit is greater when neighbours across a district do it too.

Variety choice

A variety with good resistance to the diseases common in your district lowers disease pressure before the season starts and reduces how often a fungicide is needed. Agriculture Victoria’s annual Cereal and Pulse Disease Guides, released in May 2026 with GRDC support, rate wheat, barley, oat, lentil, faba bean and chickpea varieties for their resistance or susceptibility to a range of diseases.

If you farm outside Victoria, check whether your state agriculture department publishes a similar guide. The GRDC National Variety Trials also provide disease ratings that you can filter by crop and location.

Rotation and crop competition

Changing crops and pastures breaks the life cycles of weeds and diseases that favour one host. It also opens up different control options from year to year.

For weeds, WeedSmart’s Big 6 program groups the tactics into six areas. These include rotating crops and pastures, making the crop more competitive and controlling weed seeds at harvest. The aim is to shrink the weed seed bank over time, which in turn lowers the chance of resistance developing.

Stubble decisions affect weeds, disease and sowing all at once. CSIRO’s view on retaining stubble while keeping weeds under control is a useful starting point.

Monitoring and records

An integrated plan depends on knowing what is actually in the crop. Regular, planned crop checks, with extra attention to spots where problems tend to start, pick up issues early, while there are still more ways to deal with them. Simple records help you compare seasons and see whether a tactic is working. Useful details to record include paddock history, weed and disease observations, what was applied and when, and the results.

For weeds, resistance testing replaces guesswork with evidence. GRDC’s advice on testing for herbicide resistance notes that weed seed can be collected during or after harvest and sent to a testing service over summer, with results back in time for autumn planning.

Chemical control as one tool

Herbicides and fungicides remain important. An integrated plan uses them where they add most and takes care not to wear them out. CropLife Australia updates its resistance management strategies for herbicides, fungicides and insecticides each year and publishes them free on its StewardshipFirst site, searchable by crop, pest and product type. Among other things, the strategies cover how to vary and combine modes of action.

The product label is the legal and practical reference for any chemical use. You can find current registered products and labels through the APVMA’s PubCRIS and permits databases. Agriculture Victoria’s page on off-label chemical use explains the requirements that apply in Victoria. If you farm elsewhere, check with your own state’s agriculture department, and talk to your agronomist before changing how you use any product.

Putting a plan together

An integrated plan doesn’t need to be complex. A practical way to start:

1. List the weeds and diseases that cost you most, paddock by paddock, using your records and what you saw last season.
2. For each one, work out where it comes from and when the crop is most exposed: seed bank, stubble, the green bridge, machinery or bought-in material.
3. Pick at least one tactic for each stage: before sowing, in crop and at or after harvest. Make sure the plan doesn’t depend on one chemical group.
4. Decide how and when you will monitor, and what you will record.
5. After harvest, review what worked, test suspect weed populations for resistance and adjust the plan for next season.

Where to get help

An agronomist or crop consultant who knows your district can help you rank your problems and choose tactics that suit your crops, soils and machinery. Your state agriculture department can point you to local disease guides, weed information and the chemical-use rules that apply where you farm.

For a deeper national reference on weeds, GRDC’s Integrated Weed Management Manual covers tactics, herbicide resistance and putting a plan in place. Farm Table’s crop management resources include related guides, such as improving control of summer weeds.