> ## 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.

# Diagnose and Respond to Brown Planthopper (BPH) in Rice

> Identify brown planthopper (BPH) from circular hopperburn patches of dried plants and honeydew at the base of the canopy, and control it with resistant varieties, natural enemies, and selective insecticide only when scouting justifies it.

Brown planthopper (*Nilaparvata lugens*, BPH) sucks sap from the base of rice plants. In severe outbreaks it causes "hopperburn": circular patches of dried, dead plants that expand outward. BPH also transmits rice grassy stunt virus and rice ragged stunt virus. Excessive insecticide use has repeatedly triggered BPH resurgence by killing natural enemies.

## When rice is most vulnerable

From active tillering through grain filling. BPH populations build fastest in the closed dense canopy of the reproductive stage.

## How brown planthopper shows in satellite data

* **Circular, expanding patches of dried plants** - one of the most distinctive biotic signatures visible in high-resolution imagery.
* Sudden NDVI drop in localized circular zones is the classic "hopperburn" signature.
* Different from drought (which follows topography and slope) and different from disease patches (usually not circular).

<Warning>
  Hopperburn is a late-stage signal. By the time it is visible from satellite, damage is already severe. Ground scouting at the canopy base is essential for early detection.
</Warning>

## Field symptoms

* Insects clustered at the base of the plant, especially just above the waterline
* Sticky honeydew and sooty mold on the lower plant parts
* Yellowing then browning of leaves from the bottom up
* **Hopperburn**: circular patches of dried, dead plants, expanding outward day by day
* Reduced tillering and grain fill; empty panicles on severely affected plants

## Reduce the damage by

* **Grow resistant varieties** carrying *Bph* genes - the primary control; rotate genes across seasons.
* **Preserve natural enemies** (mirid bugs, spiders, water striders) - do not spray broad-spectrum insecticides prophylactically.
* **Avoid excessive N and dense planting**, which favor BPH population growth.
* **Drain the field temporarily** to expose insects on the stem base and reduce humidity at the plant base.
* **Selective insecticide** (buprofezin, pymetrozine, or neonicotinoid, following local resistance guidance) only when scouting shows the economic threshold has been crossed.
* **Never use pyrethroids** on BPH - they trigger resurgence by killing predators without controlling BPH effectively.
* **Synchronized planting** across an area reduces continuous BPH breeding.

## Set an alert for early warning

<Tip>
  Turn the diagnosis into a trigger. Configure alerts to catch small hopperburn patches before they merge into field-scale damage.
</Tip>

Recommended settings for brown planthopper on rice:

* **NDVI drop alert** - trigger on any localized drop of 0.15 or more within a single field during tillering to grain filling.
* **New Imagery alert** during the reproductive stage on high-N, dense-canopy fields.

## Related

* [Rice Diagnosis](/guides/Crop/Rice/rice-abiotic-stress)
* [Nitrogen](/guides/Crop/Rice/nutrient/nitrogen) - excess N feeds BPH populations.
* [Set up automated crop alerts](/guides/alerts-notifications)