> ## Documentation Index > Fetch the complete documentation index at: https://badixth-dc85e378.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Rice Diagnosis: Decide What an Alert Means and What to Do > The starting point for interpreting rice field alerts. Covers abiotic stress today (drought, salinity, poor soil, submergence), with room for biotic stress and nutrient deficiency next. When an alert fires on a rice field, the platform tells you *something changed*. This guide helps you decide *what changed and what to do*. Use it as the bridge between a triggered [alert](/guides/alerts-notifications) and a field action. For the standard walk and inspection sequence a scout should follow on the ground, see [Field Walk Protocol](/guides/Crop/Rice/field-walk-protocol). ## What this guide covers Rice diagnosis is organized around three pillars, matching the decision tree a scout actually uses in the field. Environmental causes: drought, salinity, poor soil, submergence. Best-detected group by satellite. N, P, K, Zn, S, and iron toxicity. Highest platform value: NDRE is designed for this. Diseases, insect pests, and weeds. Imagery narrows *where* to scout; a scout confirms *what*. ## How to use the three pillars Use the pattern in the imagery to decide which pillar to open first: | What you see | Start with | | ---------------------------------------------------------------- | ----------------------------------------------- | | Whole field or whole zones stressed after weather event | Abiotic stress | | Uniform yellowing without a clear environment cause | Nutrient deficiency | | Patchy, spreading, or symptoms concentrated on individual plants | Biotic stress | | A field that never green-fills despite adequate inputs | Check all three - overlapping causes are common | ## Growth-stage vulnerability Different stresses hurt rice at different growth stages. Match the stage to the likely cause before opening a specific stress page. **Three stage vocabularies are in use across the rice pages, and they do not match.** This table has four classes, the [field walk record](/guides/Crop/Rice/field-walk-protocol) asks for one of six, and [Rice Ecosystems](/guides/Crop/Rice/rice-ecosystems) resolves bands against five — with two more names again on the flood-prone table. **The ecosystems page is the authority for anything that resolves a band.** Everything else maps onto it: | Field walk records | This page calls it | Band phase on the ecosystems page | | ------------------ | ------------------------ | ---------------------------------------------------------- | | Seedling | Seedling / transplanting | Transplanting / early vegetative | | Tillering | Tillering | Tillering *(flood-prone: tillering / elongation)* | | Booting | Booting to flowering | Panicle initiation / booting *(flood-prone: reproductive)* | | Heading | Booting to flowering | Heading / flowering | | Grain fill | Grain filling | Ripening / maturity | | Maturity | Grain filling | Ripening / maturity | **Two joins are lossy and worth knowing about.** *Booting to flowering* here covers two band phases with different bands — on irrigated lowland, 0.65 – 0.80 and 0.75 – 0.90. And *grain fill* and *maturity* both land on one band phase, so a scout distinguishing them gains nothing a band can read. A recorded stage alone never resolves a band. **The band resolves from the establishment date and the ecosystem**; the stage is what the scout saw, and the two are reconciled here rather than assumed equal. | Growth stage | Most damaging causes | | ------------------------ | ------------------------------------------------------------------------------------- | | Seedling / transplanting | Salinity, submergence, zinc deficiency, bakanae, tungro | | Tillering | Drought, poor soil, N and P deficiency, gall midge, sheath blight | | Booting to flowering | Drought (highest yield impact), salinity, K deficiency, blast, stem borer, false smut | | Grain filling | Drought, submergence, brown planthopper, rice bug, sheath blight | ## The three pillars ### Abiotic stress Environmental causes account for the majority of yield loss worldwide and show clearly in satellite imagery. Start here when the pattern follows topography, water flow, or a weather event. NDWI drops before NDVI. Leaf rolling, stunted growth, burning leaf tips, whiteheads at flowering. Patchy NDVI in low-lying or coastal zones. Brown leaf tips, chlorotic patches, white panicle branches. Persistently low NDVI and NDRE across the whole field or repeatable weak zones season after season. Sudden NDVI collapse in flood-prone zones after heavy rain. Full or partial disappearance of canopy. ### Nutrient deficiency Nutrient limitation looks similar to abiotic stress but responds to fertilizer, not to weather or drainage. NDRE is the leading spectral indicator - use it from tillering onward. Uniform pale-green canopy, older leaves first. Low NDRE. Dark-green stunted plants, reddish-purple older leaves. Yellow-brown scorching along older leaf margins. Increased lodging. Patchy dusty-brown blotches at early tillering on high-pH soils. Pale-yellow young leaves (opposite of N). Field does not respond to N top-dressing. Bronze-orange stippling on lower leaves in acid, waterlogged zones. ### Biotic stress Living causes: diseases, insect pests, and weeds. Satellites narrow *where* to scout, but ground confirmation is essential before treatment. Satellites are excellent at abiotic and good at nutrient. Biotic detection needs ground truth. Always confirm the identification with a scout before applying pesticides. **Diseases** Diamond-shaped lesions; neck blast causes whiteheads. Yellow wavy lesions from leaf tips; bacterial ooze in morning. Greenish-grey lesions on lower sheaths in dense high-N canopies. Yellow-orange stunted plants; transmitted by green leafhopper. Discolored flag-leaf sheath; panicle fails to emerge properly. Yellow-green fungal balls replacing grains. Preventive fungicide at booting only. Abnormally tall, pale, thin seedlings. Seed-borne. **Insect pests** Circular hopperburn patches; honeydew at plant base. Deadhearts at vegetative stage; whiteheads at heading. Folded leaves with white longitudinal streaks. Empty, spotted grains at milk stage; strong bug odor. Silver shoots (onion leaves) replacing normal leaves. No panicle on affected tillers. Sudden defoliation moving in waves; nocturnal. **Weeds** Barnyardgrass; mimics rice early. Highest weed-driven yield loss. Triangular stems; nutsedge tubers persist across seasons. Wide leaves and showy flowers. Suppressed by shallow flooding. ## Decision flow Check the season record for the field. Match the stage to the vulnerability table above. * NDWI drops first, NDVI follows: think **drought**. * NDVI collapses suddenly after rain: think **submergence**. * NDVI patchy and stable-low, coastal / low-lying: think **salinity**. * Field-scale low NDRE, uniform yellowing: think **N deficiency** (or S if N top-dressing did not help). * Circular expanding pale patches: think **hopperburn** (BPH). * Rapid, large drop between passes: think **armyworm** or **BLB after a storm**. Open the matching stress page and compare the symptom list to what a scout sees on the ground. Symptoms rule stresses in or out faster than imagery alone. Apply the recommended action. Then use the [Alerts](/guides/alerts-notifications) page to configure a follow-up alert so the same stress is caught earlier next time. ## Related * [Field Walk Protocol](/guides/Crop/Rice/field-walk-protocol) - the standard scout inspection sequence this diagnosis feeds into. * [Healthy NDVI ranges for paddy across rice ecosystems](/guides/Crop/rice-ecosystems) - baseline values to compare an alert against. * [Set up automated crop alerts](/guides/alerts-notifications) - configure the triggers that surface these stresses. * [Monitor crop health across fields](/guides/crop-health-monitoring) - view the imagery that alerts are derived from. * [Analyze crop performance across a full season](/guides/seasonal-analysis) - the right tool for chronic zone problems. This diagnosis covers the three major stress groups in rice. Rare stresses (cold, heat, herbicide phytotoxicity, mechanical damage) are not yet documented and can be added as separate short pages when needed.