Weed Seed Wizard

The Weed Seed Wizard uses farm-specific information. The user inputs their paddock soil type, local weather, and the weed species specific to their farm in the setup scenario window.  

As the model simulates the dormancy and germinability of each weed species against soil moisture and temperature, major inputs that influence the predictions include weather characteristics such as rainfall, daily temperature, and evaporation, plus soil type (which provides information on soil water-holding capacity). 

The tool comes with a set of weather files in CSV format for each Australian state or territory. The user can choose the file for the site closest to their farm or set up their own file from their weather stations or from weather providers. 

There is a range of soil types (sand to clay), and a choice of weed species (Table 1). 

Table 1 Weed species 

Users input their past management records or plans in the event management window. This window shows a sequence of management events for a specific paddock, where each event is expressed as a date and a description of the event. The choice of events is very flexible to reflect the multitude of options growers have and how they can integrate them in their crop management (Table 2). 

Table 2 Management events in the Weed Seed Wizard and the choices available within each. Note: ‘New *’ indicates you can create your own custom event (such as till event, herbicide) 

After the scenario has been simulated, there are three main sets of results (or outputs) to be viewed from the simulation window; the seedbank, plant numbers, and crop yields. These outputs show how the management decisions affect the weed seedbank numbers, the weed germination and density and ultimately, the crop yield. 

Each weed species has different dormancy and germination characteristics: 

• Some species have no dormancy, others have an after-ripening requirement but can germinate with the opening rains while others require specific environmental (light, temperature, etc) cues for dormancy to be broken and germination to commence. Different management techniques, for example a tillage operation, can redistribute the seed and place it into an environment which is more (or less) conducive to germination and emergence. The Wizard portrays the number of seeds in the seedbank over time, where numbers increase each year with seed production and seedbank replenishment then decline due to germination and seed decay. 
• The simulated plant numbers are shown to increase with every germination (following a breakdown in dormancy and an adequate rainfall event) and to decrease with each control event (for example, a herbicide application or tillage event) until the plants are removed at harvest. By exploring a range of simulated scenarios, the user can easily see how weed and seed numbers can be affected, potentially over several seasons by the choice of management strategy. Users can also establish a herbicide resistance status for each species by changing the percent kill rate of a herbicide choice. 

The Weed Seed Wizard also estimates how much crop yield is reduced by weed competition and provides a comparison with the potential harvest yield without weeds. The user can then calculate the income of the scenario and compare the income generated by weed-free and weed-reduced yields. This is an important tool for growers as they can easily see how weeds can affect crop yields and ultimately profitability by quickly assessing the disparity between the potential and modelled yields.