# Weed Patches Detection and Herbicide VRA Rx Map

## When to use this workflow

* **Early–mid season** when weed patches create clear spectral contrast vs. crop/soil.
* **Post‑emerge targeted sprays** or **patch‑spray clean‑ups**.
* Fields with **known weedy headlands, drowned‑out spots, compaction bands,** or prior escape areas.

> Upsampling to 1 m improves map geometry (smoother polygons for controllers) but doesn’t invent new detail beyond the sensor’s native resolution.

## Option A — Zoning Workflow (1 min video)

{% hint style="warning" %}
The tutorial below supports multiple languages. Choose the one that best fits you from the language icon <img src="/files/k91cBV1hRmp36OjTv4K6" alt="" data-size="line">.&#x20;
{% endhint %}

{% @arcade/embed flowId="57JEr489MVHJ2PpreES0" url="<https://app.arcade.software/share/57JEr489MVHJ2PpreES0>" %}

{% stepper %}
{% step %}

### Select Image

<figure><img src="/files/ELab3mPp1vGsC39cQYLy" alt="Planet labs imagery with applied contrast WDRVI index in GeoPard"><figcaption><p>Planet labs imagery with applied contrast WDRVI index in GeoPard</p></figcaption></figure>
{% endstep %}

{% step %}

### Create VRA Rx map&#x20;

<figure><img src="/files/GPDMyTvUPr9wqXV8lGCR" alt="VRA herbicide map saves you $2200 per operation"><figcaption></figcaption></figure>
{% endstep %}

{% step %}

### Export machine-ready Prescription map file

<figure><img src="/files/u5jbV1xIyiXWpIo2EKTI" alt="Export machine-ready Prescription map file"><figcaption><p>Export VR herbicide application map as shp, iso or send directly to the connected machines</p></figcaption></figure>
{% endstep %}
{% endstepper %}

## Option B — Equation‑Based

[Equation based](/geopard-tutorials/product-tour-web-app/equation-based-analytics.md) map could also be used for VRA herbicide application map.

## Financial outcomes & ROI

| Metric                                            |                                                Value |
| ------------------------------------------------- | ---------------------------------------------------: |
| Field size                                        |                                         **311.3 ac** |
| VRA zones (area share)                            | **OFF:** 142.8 ac (45.9%) • **ON:** 168.5 ac (54.1%) |
| ON rate (herbicide)                               |                                         **1.3 L/ac** |
| Average rate with VRA                             |                                         **0.7 L/ac** |
| Total volume if flat rate (1.3 L/ac on all acres) |                                          **404.7 L** |
| Total volume with VRA (ON/OFF)                    |                                          **219.1 L** |
| **Volume saved vs. flat rate**                    |                                  **185.6 L (45.9%)** |
| Price per liter                                   |                                         **$12.00/L** |
| **Product cost saved vs. flat rate**              |                                         **$2 227.8** |
| **Alt. scenario – vs. your “custom” rate mix**    |                         **154.5 L saved → $1 854.2** |

##

## Q\&A&#x20;

* **Visual overlay**: Toggle imagery + zones; check headlands and wetlands.
* **Spot‑check**: 3–5 biggest patches on the ground or via high‑res drone/phone.
* **Edge artifacts**: If you see boundary stripes, add **boundary buffer (−3 to −6 m)** or re‑threshold.
* **Cloud/shadow**: If present, switch date or mask using the cloud layer.
* **Patches look noisy** → Raise **min area**, add **smoothing**, or use **Planet 3 m image**.

***

## Recommended defaults (tune per field)

* **Index**: Start with [**OSAVI**](/geopard-tutorials/product-tour-web-app/satellite-monitoring/indices-for-crops-and-soils.md) until canopy closes; try **CIred‑edge** from **6–9 leaf** stage onward.
* **Min patch size**: **≥ 2× section area** (example: 12 m boom, 3 m section ⇒ \~72 m²). Round up for smoother control.
* **Buffers**: **−3 m** field edge; **no‑spray zones** as per label/regulation.

***

## Export tips by controller

* **SHP**: Ensure attribute `RATE` (numeric).
* **ISOXML**: Name the Operation type, **Product**, and **Units** exactly as your terminal expects.
* **John Deere Ops Center**: few-clicks export into Ops Center as [Rx file](/geopard-tutorials/product-tour-web-app/export-download/export-to-myjohndeere.md) or [WorkPlan](/geopard-tutorials/product-tour-web-app/john-deere-operations-center-integration/8.-export-rx-maps-to-john-deere-operations-center-as-work-plans.md)

***

## Compliance & agronomy notes

* Follow **label rates**, **buffer zones**, **wind** and **drift** rules.
* Patch‑spray success improves if you **re‑run this workflow 7–14 days** after emergence for escapes.
* Keep a **before/after** photo set to prove efficacy and refine thresholds next time.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.geopard.tech/geopard-tutorials/agronomy/weed-patches-detection-and-herbicide-vra-rx-map.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.