Coastal Rosemary with Spider Mites? Rare but Treatable

Westringia fruticosa

Susceptibility: Low Severity: High Difficulty: Easy

Spider mites are tiny arachnids (less than 1/20 inch long) related to spiders and ticks that feed on plant sap. They thrive in hot, dry conditions and can cause significant damage to ornamental and vegetable plants. During severe infestations, crop losses can reach 14% or higher as these pests disrupt vital plant processes including photosynthesis, carbon dioxide absorption, and transpiration.

🔍 Symptoms

• Pale discoloration spots on leaves
• Fine silk webbing covering leaves and stems
• Tiny yellow or white speckles on leaf surface (stippling)
• Leaves taking on yellow or bronzed appearance
• Flecking and scorching of foliage
• Reduced chlorophyll content
• Premature leaf drop and potential plant death

❓ Possible Causes

→ Hot and dry weather conditions
→ Low humidity environments
→ Water-stressed plants
→ Dusty conditions on foliage
→ Overuse of pesticides killing natural predators
→ Poor air circulation around plants
→ Bringing infested plants indoors or near healthy plants

💊 Treatment

⚡

Quick Fixes

Step 1

Immediately spray all affected plants with rubbing alcohol (70% isopropyl) diluted 1:1 with water

Step 2

Apply insecticidal soap or horticultural oil directly to visible mites

Step 3

Wipe leaves with damp cloth to physically remove mites and webbing

Step 4

Spray undersides of all leaves thoroughly with water mist

Step 5

Repeat alcohol or soap treatment every 3 days for 2 weeks

🌿

Organic Treatment

Step 1

Isolate infected plants immediately to prevent spread

Step 2

Spray undersides of leaves with strong water stream daily to dislodge mites

Step 3

Apply neem oil solution (mix with Coco-Wet) every 3-5 days, covering all plant parts

Step 4

Use insecticidal soap spray at 3-day intervals until control is achieved

Step 5

Apply diatomaceous earth to soil surface and lower leaves

Step 6

Introduce beneficial predatory mites (Phytoseiulus persimilis) for ongoing control

Step 7

Monitor plant daily and repeat treatments as needed

🛡️ Prevention

✓ Maintain adequate irrigation and soil moisture levels
✓ Inspect plants weekly for early signs of webbing or stippling
✓ Wash trees and vines with water mid-season to remove dust
✓ Install drip irrigation systems for consistent moisture
✓ Track hot and dry weather and increase watering during high-risk periods
✓ Provide shading during extreme heat
✓ Encourage natural predators like lady beetles, predatory mites, and minute pirate bugs
✓ Quarantine new plants before introducing them to your collection
✓ Maintain optimal growing conditions through proper fertilization and temperature control

🌱 Care Guide: Coastal Rosemary

💧 How to Water

Water every 7-14 days during establishment. Once established, Coastal Rosemary is highly drought-tolerant and may only need watering during extended dry spells. Avoid overwatering as this can cause root rot. Ensure soil drains freely.

☀️ Lighting

Plant in full sun for the best flowering and growth. Coastal Rosemary tolerates partial shade but may produce fewer flowers and grow more slowly. It performs excellently in open, sunny spots, including exposed coastal positions.

🪴 Ideal Soil

Requires well-draining soil. Tolerates sandy, loamy, and even rocky soils. Avoid heavy clay or waterlogged soils. A slightly acidic to neutral pH (6.0-7.0) is ideal. Avoid high-phosphorus fertilizers, which can cause nutrient imbalances in native Australian plants.

See more: Coastal Rosemary → See more: Spider Mites →