Red Spider Mite

This damage is caused by the two-spotted spider mite, Tetranychus urticae. Despite the name, it is an arachnid rather than an insect — a tiny piercing-sucking pest that drains chlorophyll from leaf cells, causing progressive stippling, bronzing, and leaf drop. Outbreaks flare under hot, dry, dusty conditions where natural enemies are suppressed.

The mites feed almost exclusively on leaf chlorophyll. As the colony builds, leaves lose their green pigment and turn a dull bronze or silver, then drop. Defoliation typically progresses from the lower leaves upward toward the shoot tips, canes desiccate, and severely infested plants may die outright if the population is not brought under control.

The mechanism by which spider mites cause leaf curl is similar to that of thrips. They pierce and destroy cells on the leaf's underside. This damaged cell layer contracts while the upper surface continues to grow, forcing the leaf blade to curl upward.

Once fine webbing or moving specks are detected on the leaf underside, act decisively:

• Spray water forcefully on leaf undersides to dislodge mites and eggs mechanically.
• Raise humidity around the plant by misting — spider mites thrive in dry air.
• Prune out and destroy heavily damaged leaves (never compost them); isolate infested plants from healthy specimens to prevent airborne drift.
• Apply neem oil or a specialised miticide (Ortus 5SC) — spray to thorough wetness on both leaf surfaces, especially the underside, in the late afternoon.
• [After 5 days] Reapply to kill newly hatched eggs; rotate active ingredients (neem / Ortus / Nissorun) to prevent resistance build-up.
• [After 10 days] Check for webbing and yellow stippling on leaves; if any remain, continue spraying.

Recommended products

1. Pure Neem oil — Plant-derived organic miticide containing azadirachtin; disrupts mite development, suppresses feeding, halts egg-laying, and causes gradual mortality. Safe for the home gardener and the wider garden ecosystem.

   • Dosage: 5 ml neem oil + 5 ml dish soap (as emulsifier) per 1 L of water. Stir until the mixture turns a uniform milky white before transferring to the sprayer.
   • Application: Drench both leaf surfaces, paying particular attention to the underside. Spray only in the late afternoon (after 5 pm) and rinse the foliage with clean water the following morning to prevent phytotoxic burn and restore photosynthesis.
   • Frequency: Curative — every 2–3 days until the mites are gone. Preventive — every 7–10 days.
   • Where to buy: Shopee — Pure neem oil.

2. Ortus 5SC — Specialised contact and stomach-action acaricide that controls both juvenile and adult mites. Widely available and fast-acting.

   • Dosage: 10–12 ml per 16 L of water (approximately 0.7 ml per litre).
   • Application: Spray to thorough wetness on both leaf surfaces, especially the underside. Apply in the early morning or late afternoon.
   • Frequency: For heavy infestations, two applications 3–5 days apart.
   • Where to buy: Shopee — Ortus 5SC.

3. Pestoil (SK horticultural mineral oil) — Refined horticultural mineral oil that coats and asphyxiates mites and eggs. Very safe for people and the environment.

   • Dosage: 40–60 ml per 16 L of water (approximately 3–4 ml per litre).
   • Application: Spray thoroughly to the underside of leaves. Caution: never apply during intense sunshine — the oil film can scorch foliage.
   • Frequency: Every 7 days as both preventive and curative.
   • Where to buy: Lazada — SK Enspray mineral oil.

4. Nissorun 5EC — Specialist ovicide and juvenile-stage miticide targeting eggs and immature mites, preventing the next generation from establishing.

   • Dosage: 10 ml per 16 L of water.
   • Application: Typically tank-mixed with Ortus to control adults and eggs simultaneously ("root and shoot").
   • Frequency: Reapply after 5 days to mop up any newly hatched eggs.
   • Where to buy: Shopee — Nissorun.

Practical tip: add a few drops of dish soap or a wetting agent to miticide sprays — the waxy, hairy surface of rose foliage otherwise sheds the spray and reduces contact with the mites.

• Keep the garden clean and remove old, dust-covered leaves around the base — open, well-ventilated canopies are hostile to spider mites.
• Prune out aged, weak, or pest-damaged canes and destroy them.