Thrips

Thrips are tiny (1–2 mm) piercing-sucking insects in the order Thysanoptera, most commonly Frankliniella occidentalis (the western flower thrips) and Thrips tabaci (the onion thrips) on roses. They rasp and suck cell contents from leaves, buds, and petals, leaving silvery streaks or coppery sheen on the leaf surface, deformed flowers, and tell-tale black faecal specks. Thrips flourish in hot, dry conditions (25–35 °C with low humidity), reproduce extremely rapidly, and develop insecticide resistance quickly if products are not rotated. Beyond direct feeding damage, several species act as vectors of plant viruses such as Tomato Spotted Wilt Virus (TSWV). Adult thrips are also wind-dispersed over long distances, allowing outbreaks to spread quickly — and a heavily damaged plant may take months to recover and push fresh, undamaged growth.

When thrips feed on the underside of the leaf, they destroy epidermal cells. These cells die and contract, creating mechanical tension. Meanwhile, the upper leaf surface continues to expand, forcing the leaf to curl upward to relieve the surface pressure.

When you spot curled young foliage, blackened buds, or silvery streaks on petals, act immediately:

• Remove severely damaged buds, blooms, and curled young leaves (roughly 80% of the thrips population is sheltering there); bag the prunings and dispose of them off-site, never at the base of the plant. Isolate infested plants from healthy roses.
• Hang blue or yellow sticky traps near the plant to capture adults and monitor populations.
• Hose the underside of leaves and leaf axils with a strong water jet to mechanically dislodge adult thrips.
• Spray neem oil or a thrips-targeted insecticide (Radiant 60SC / Confidor 200SL / Movento) in the late evening or early morning (when thrips are most active); drench both leaf surfaces and wet the soil surface where thrips pupate.
• [After 5 days] Reapply to catch newly hatched thrips; you must rotate between at least two products to prevent resistance.
• [After 10 days] Tap a bloom over white paper to count remaining thrips; if any remain, continue spraying.

Recommended products

1. Radiant 60SC (US-made — highly effective and gentle) — Biologically derived spinosyn insecticide with potent contact and stomach activity. Very safe on roses and does not scorch tender growth.

   • Dosage: One 15 ml sachet per 16–20 L of water (or 1 ml per litre).
   • Frequency: Two applications 3–5 days apart to mop up newly hatched larvae.
   • Where to buy: Shopee — Radiant 60SC

2. Confidor 200SL (Bayer — long residual) — Highly systemic neonicotinoid that permeates plant tissue. Thrips ingest the active ingredient through sap feeding and rapidly become paralysed.

   • Dosage: 1 ml per 1.5–2 L of water.
   • Frequency: Every 7–10 days under heavy pest pressure.
   • Where to buy: Lazada — Confidor Bayer

3. Movento 150OD (Two-way systemic — kills eggs and juveniles) — Two-way systemic activity (both upward to shoots and downward to roots), reaching even the thrips sheltering deepest inside buds.

   • Dosage: 1–2 ml per 1 L of water.
   • Frequency: Apply at the first sign of a thrips resurgence.
   • Where to buy: Shopee — Movento.

4. Cold-pressed pure neem oil (safe organic option) — Plant-derived product containing azadirachtin. Rather than killing on contact, neem disrupts thrips reproduction, suppresses feeding, causes gradual mortality, and inhibits egg hatch — extremely safe for people and the environment.

   • Dosage: Curative: 5 ml neem oil + 5 ml dish soap (as emulsifier) per 1 L of water. Preventive: 1–2 ml neem oil + 2 ml dish soap per 1 L of water.
   • Frequency: Curative: every 2–3 days in the late afternoon, continuously for two weeks. Preventive: once weekly.

Critical reminder: thrips have a very short life cycle and develop resistance quickly. You must reapply after 3–5 days to kill the next hatch — a single spray will be followed by rapid resurgence.

• Maintain an open, well-ventilated canopy and avoid overcrowded plantings.
• Maintain adequate humidity — thrips prefer hot, dry conditions.
• Inspect leaf undersides and flowers regularly (use a hand lens if needed).
• Plant repellent companions such as basil and marigold near the rose bed.
• Apply preventive sprays of neem oil or insecticidal soap on a regular schedule.