Rice Field Walk Protocol: Standard Scout Inspection Sequence

The standard walk and inspection sequence for rice scouts: what to look at, in what order, and what to record on each transect stop and whole paddy field.

Rice scouting is not the same as oil palm scouting. You are looking at a uniform seasonal canopy of many small plants, not a stand of long-lived individuals. A rice field changes in days, not months. Use this protocol as the checklist for a routine weekly walk, a follow-up on a satellite alert, or a targeted inspection during a critical growth stage.

When to run this protocol

• Weekly during active growth (tillering through grain fill)
• Twice weekly during booting to heading (highest yield risk from blast, BPH, stem borer)
• Immediately on any field flagged by a satellite alert or when neighboring fields report an outbreak
• Within 48 hours of a weather event (heavy rain, storm, prolonged cloudy or humid spell, cold snap)
• Before and after every fertilizer, herbicide, or pesticide application

What to bring

• Field map with block or plot IDs and the planned walk transect
• Field record sheet or mobile app tied to the field data model
• Leaf color chart (LCC) or SPAD meter (N status) — note the chart’s panel count before you start
• White tray or beat sheet (BPH, planthopper, egg mass sampling)
• Sweep net (leafhoppers, adult moths, rice bug)
• Small hand lens (10x) for lesions and hopper nymphs
• Sample bags for leaf, tiller, panicle, and soil samples
• Camera or phone (photograph every anomaly)
• GPS for stop-level records
• Rubber boots and a machete

Choose a walk pattern

Unlike oil palm, you cannot inspect every plant. Sample the field along a fixed pattern so results are repeatable week to week.

Field shape and size	Recommended pattern	Stops
Small (< 0.5 ha), regular	Diagonal (single X)	5 stops (four corners + center)
Medium (0.5 to 2 ha), regular	Double diagonal (X)	8 to 10 stops
Large (> 2 ha) or irregular	W-pattern or zig-zag	10 to 15 stops
Following a satellite alert	Straight line through the flagged zone + one control stop outside	5 to 8 stops in-zone, 2 outside

At each stop, inspect a 1 m x 1 m quadrat (or 20 hills for transplanted paddy). Always keep the same stop count and quadrat size on the same field so the trend is comparable.

Walk into the wind where possible. Insects fly and jump away from you rather than into your face, and you disturb fewer nymphs before you can count them.

The 5-step inspection sequence

Run each step at every stop, in this order. Skipping a step is the most common cause of missed diagnoses.

1. Stand and canopy from above

   Look at the stop from standing height first. This tells you about whole-field uniformity and recent (days to weeks) stress before you get close.

   • Canopy color - uniform green, pale, dark, patchy, or yellowing? (N, S, drought, salinity)
   • Canopy height - even, or shorter in patches? (Waterlogging, poor soil, tungro, zinc)
   • Tiller density - dense, thin, or gaps? (Poor establishment, gall midge, stem borer, weeds)
   • Standing water - present, uneven, drained, or scummy? (Irrigation status, iron toxicity, algal bloom)
   • Weed pressure - grasses, sedges, or broadleaf mixed in with the crop? (Weed competition)
   • Lodging - plants leaning or flattened in patches? (K deficiency, storm, sheath blight, BPH hopperburn)
2. Leaf color and position (nutrient and disease decision)

   Bend down and pick 5 to 10 representative hills. Note which leaves are affected and where on the plant.

   • Whole canopy pale, older leaves first - Nitrogen
   • Whole canopy pale, young leaves first - Sulfur (opposite of N)
   • Yellow-brown scorching along older leaf tips and margins - Potassium
   • Dark green, stunted, reddish-purple older leaves - Phosphorus
   • Patchy dusty-brown blotches on lower leaves at early tillering - Zinc (high-pH soils)
   • Bronze-orange stippling on lower leaves in wet, acid zones - Iron toxicity
   • Diamond-shaped lesions, gray center and brown border - Blast (leaf)
   • Yellow wavy lesions from the leaf tip, bacterial ooze in morning - Bacterial leaf blight
   • Folded leaves with white longitudinal streaks - Leaffolder
   • Yellow-orange stunted plants, few tillers - Tungro

   Take the LCC or SPAD reading here. Record the reading, not just “pale” or “green” — and record which chart you used, because the panel numbers on a 4-panel chart and a 6-panel chart are not the same greens. See Leaf colour readings.

3. Tiller base, sheath, and stem

   Part the canopy and inspect the base of 5 to 10 hills. This is where most disease and insect activity starts, hidden from above.

   • Oval greenish-grey lesions on lower sheaths, spreading up - Sheath blight
   • Discolored, rotting flag-leaf sheath, panicle stuck inside - Sheath rot
   • Central deadheart (dead central shoot) that pulls out easily - Stem borer (vegetative stage)
   • Silver-shoot (onion-leaf) tiller with no panicle - Gall midge
   • Sticky honeydew, sooty mold, hoppers at the base - Brown planthopper
   • Abnormally tall, pale, thin seedlings - Bakanae (seedling/early)
   • Frass, bore holes, or split stems - Stem borer (later instars)

   Tap 5 hills over a white tray. Count hoppers, spiders, and other insects. Record the count per hill.

4. Panicle and grain (only from booting onward)

   Once panicles are exerted, check panicle load and any damage. This is the yield-critical inspection.

   • Whiteheads (empty, upright, pale panicles) - Neck blast, stem borer, or terminal drought
   • Brown to black rotted collar just below the panicle - Neck blast
   • Yellow-green fungal balls replacing grains - False smut
   • Sucked, discolored, empty grains at milk stage + strong bug odor - Rice bug
   • Partial panicle emergence, discolored sheath - Sheath rot
   • Panicles hanging, dry, or shattering - Bird damage, late-stage blast, or over-mature
   • Grain fill uneven - Cold, heat, or nutrient stress at flowering

   Count filled vs unfilled grains on 5 panicles. Record the percentage.

5. Water, soil, and field edge

   Finish the stop by looking at the ground and the bund.

   • Water depth - too deep, too shallow, or absent? (Submergence, drought, weed pressure)
   • Water color and film - rust film, oily sheen (iron toxicity), green algal bloom (excess N), clear (normal)
   • Bund integrity - cracks, leaks, weed hosts on the bund? (Rat holes, weed seed source)
   • Rat runs and cuts - chewed tillers or panicles near the bund?
   • Snail and shell counts - golden apple snail damage on young transplants?
   • Herbicide edge burn - yellowing or bleaching in a straight line? (Drift or misapplication)

   Photograph any anomaly. Record the GPS point of the stop.

What to record per stop

Minimum record at every stop, whether the field is normal or not:

Field	Notes
Field and stop ID	GPS if available
Date and time	Inspection date and time of day
Growth stage	Seedling / tillering / booting / heading / grain fill / maturity — what you see, not what the band says. These six map onto the five band phases at Rice Diagnosis; the mapping is not one to one.
Days after establishment	Days from sowing or transplanting
Canopy note	Uniform / patchy / lodged / etc.
Leaf color note	LCC panel number and which chart (4-panel or 6-panel), or SPAD reading, + which leaves affected
Tiller base note	Clean / lesions / deadhearts / hoppers per hill
Panicle note (if applicable)	Whiteheads / smut balls / % filled grains
Water and soil note	Depth, color, film
Insect counts	Per hill or per sweep, by species where possible
Suspected cause	Diagnosis from the Rice Diagnosis tables
Action taken	Sample collected, treatment planned, marked for follow-up
Follow-up date	When to re-inspect

Field-level summary to record

After walking the field, record:

• Number of stops inspected
• Number and location of abnormal stops
• Pattern (scattered, edge, gradient with topography, whole-field, spreading focus)
• Average LCC or SPAD reading across all stops
• Recent weather, water management, or input events
• Growth stage and days-after-establishment at the field level
• Recommendation (treat, resample, escalate, or continue monitoring)

Pattern reading (what it likely means)

Use the walk-wide pattern to decide which pillar to open in the Rice Diagnosis guide.

Pattern across your stops	Likely pillar
Whole field uniformly off, matches weather or soil map	Abiotic or field-wide nutrient
Gradient across the field following topography or water flow	Abiotic (drainage, salinity) or soil-linked nutrient
Circular expanding pale or dry patches	Biotic - hopperburn (BPH) or sheath blight focus
Straight-line edge burn	Herbicide drift or bund-line salinity
Scattered individual hills stunted or yellow	Biotic - tungro, gall midge, or virus
Sudden defoliation between two walks	Biotic - armyworm or hail
Sudden canopy collapse after rain	Abiotic - submergence, or biotic - BLB after storm
Whiteheads at heading, no lesions	Stem borer or terminal drought
Whiteheads at heading, neck lesions	Neck blast

Linking to satellite alerts

If you were sent to this field by a satellite alert:

1. Confirm the alerted zone on the ground. Walk into it and take at least 3 in-zone stops + 2 control stops outside the zone.
2. Record whether the pattern matches (whole-field, gradient, cluster, edge).
3. Cross-check the index that moved (NDVI, NDRE, NDWI) against the Rice Diagnosis decision flow.
4. Use the Rice Diagnosis tables to move from the field pattern to a specific cause.
5. Set a follow-up alert on the same field or zone via the Alerts page.

Safety and hygiene

• Wash boots between fields to avoid moving blast spores, BLB, sheath blight sclerotia, and weed seeds.
• Do not enter another farm’s field without permission, even to sample.
• Watch for snakes in the canopy, especially at heading.
• If you touch nettle-like plants or suspect pesticide residue, do not touch your face; wash hands before eating.

Related

• Rice Diagnosis - the decision tree that this walk feeds into.
• Healthy NDVI ranges for paddy across rice ecosystems - the baseline your inspection compares against.
• Set up automated crop alerts - the triggers that dispatch this walk.
• Plan and execute field scouting routes - the mobile-app workflow that captures the records above.