Weed Patches Detection and Herbicide VRA Rx Map

Goal: Detect weed patches from satellite imagery and generate an ON/OFF (2‑zone) herbicide prescription (Rx) you can export as SHP, ISOXML, or Send to John Deere.

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)

1

Select Image

Planet labs imagery with applied contrast WDRVI index in GeoPard

2

Create VRA Rx map

3

Export machine-ready Prescription map file

Export VR herbicide application map as shp, iso or send directly to the connected machines

Option B — Equation‑Based

Equation based 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

• 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.

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Recommended defaults (tune per field)

• Index: Start with OSAVI 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.

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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 or WorkPlan

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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.