Spray Decision Calculator
Cost-aware spray or hold-off decision support using disease risk, weather windows, and inventory checks
The Spray Decision Calculator helps you decide whether spraying makes sense right now. You enter environmental conditions, course conditions, and cost information, and TurfWise calculates a recommendation that factors in disease risk, weather suitability, product cost, labour cost, and stock availability.
Spray Decision Calculator
This article refers to a live TurfWise screen. Media is omitted here so the written steps stay current across releases.
When would you use this?
- Before a spray application, to check whether conditions are actually right
- When disease pressure is building and you need to decide between spraying now or waiting
- To document a data-backed reason for spraying (useful for committee spend queries)
- When comparing the cost of spraying now versus an alternative approach
- Before committing stock -- to confirm the product is available and the cost is justified
What happens when you use it
You fill in a form with three groups of information: environmental conditions, course conditions, and costs. Then you click Generate Spray Decision.
TurfWise runs the inputs through a disease risk model and returns a recommendation with a risk label, urgency level, cost breakdown, and (optionally) a weather window check, inventory availability status, and alternative treatment comparison.
The result doesn't replace your judgement. It gives you structured evidence to support the decision you make.
How to use this page
Choose the target disease
Select the disease you're evaluating from the dropdown:
- Microdochium patch (fusarium patch)
- Dollar spot
- Anthracnose foliar blight
- Brown patch
This sets which disease risk model TurfWise uses for the analysis.
Enter environmental conditions
Fill in what you're seeing on site right now:
- Temperature (C) -- current air temperature
- Humidity (%) -- relative humidity
- Precipitation (mm) -- recent or current rainfall
- Leaf wetness (hours) -- how long the leaf surface has been wet
- Soil moisture (%) -- current soil moisture level
- Wind speed -- current wind conditions
Use measured values where you can. The more accurate your inputs, the more reliable the recommendation.
Set course conditions
Enter details about the turf you're treating:
- Grass type -- e.g. bentgrass, ryegrass, fescue
- Mowing height (mm) -- current cutting height
- Thatch depth (%) -- organic matter percentage
- Irrigation pattern -- how frequently you're irrigating
- Dew removal frequency -- how often dew is being removed
- Nitrogen level -- current nitrogen application rate
These values affect disease pressure calculations, so they influence whether the recommendation leans towards "spray now" or "monitor."
Add cost information
Enter the real cost of spraying today:
- Product name -- what you'd apply
- Unit price -- cost per unit
- Units required -- how many units for the application
- Hours required -- how long the application takes
- Hourly rate -- staff cost per hour
- Staff count -- how many people are needed
TurfWise calculates a total cost (product + labour) so you can weigh the financial side of the decision.
Enable optional checks and generate
Before clicking Generate Spray Decision, consider enabling:
- 48-hour weather window -- checks whether conditions will stay suitable for the next 48 hours (rain washing off a fresh application is wasted money)
- Inventory availability -- checks whether you have enough stock to actually do the application
- Historical context -- includes past application data for context
Click Generate Spray Decision to get the recommendation.
How to read the results
After generating, the form is replaced by a results view with three tabs: Summary, Alternatives, and Details.
Summary
Shows the headline recommendation:
- Decision -- spray or hold off, with urgency level
- Risk label and confidence -- how confident the model is
- Cost breakdown -- product cost, labour cost, and total
- Weather window status (if enabled) -- whether conditions will hold
- Inventory status (if enabled) -- whether stock is available
Alternatives
Compares different approaches, so you can see if there's a better option than spraying today.
Details
Full breakdown of the calculation, showing how each factor contributed to the risk score.
How to interpret quickly
- High risk + suitable weather + stock available = likely spray window. Act.
- High risk + unsuitable weather = delay and monitor the short-term forecast.
- Moderate risk + high cost = compare alternatives. Is the spend justified?
- Low risk + high cost = usually better to monitor and avoid unnecessary treatment.
Common problems and fixes
- "The recommendation doesn't feel right" -- Check your inputs. The most common cause is stale weather values from earlier in the day, or entering target values instead of what you actually measured.
- "Labour cost is showing as zero" -- You've left the hours or staff count fields empty. These default to zero, which underestimates the real cost.
- "Inventory check says out of stock but I know we have it" -- The inventory check uses TurfWise stock records. If stock hasn't been updated after a delivery, it won't know about it.
- "I want to recalculate with different values" -- Click the button to return to the input form (shown after results are displayed), adjust your inputs, and generate again.
Good habits that prevent issues later
- Run the calculator even when you're fairly sure you need to spray. It gives you a documented, data-backed decision -- valuable for compliance records and for explaining spend to the committee.
- Use current on-site observations, not yesterday's data. Conditions change overnight and stale inputs produce misleading recommendations.
- Check the 48-hour weather window before committing. Spraying 20 minutes before heavy rain is money down the drain.
- Compare alternatives before choosing the most expensive option. The Alternatives tab exists for exactly this reason.
Always do an on-site check
Even if the calculator says conditions are suitable, always do a visual check before spraying. Local microclimates around trees, buildings, and sheltered areas can differ from the weather data you entered.
Where this fits in TurfWise
The Spray Decision Calculator supports the decision before an application. After you've decided to spray, use the Spray Logger to record the completed application with full compliance detail.
Data from spray decisions also informs:
- Disease Prediction -- your inputs help validate the disease models
- Cost Reports -- documented cost breakdowns feed into financial reporting
- Compliance records -- having a data-backed reason for every application strengthens your audit trail
Where to find it
Open the AI Hub at /ai and click the Spray tab, or go directly to /spray-decision.