Here is a quick guide to pests and diseases that Rhododendrons can be prone to.

 

Aphids

Symptoms: Clusters of insects on young growth
Remedy: Spray with Mavrik or Confidor at 2 weekly intervals

 

Mites

Symptoms: Leaves yellow (stippled or mottled) and dehydrated in hot dry weather
Remedy: Spray with mite killer

 

Thrips

Symptoms: Leaves silver and dry. Brown-black specks appear on underside of leaves
Remedy: Spray with Mavrik or Confidor at 2-3 weekly intervals through summer

 

Sooty mould

Symptoms: Black sooty mould on leaves and twigs
Remedy: Spray with Mavrik or Confidor

 

Petal blight

Symptoms: Earliest symptom is light brown or whitish coloured circular spots on petals. Spots enlarge to form irregular blotches until whole flower collapses. Petals feel slimy when rubbed between fingers. Diseased flowers dry up and cling to the plant (leaves and stems are not affected).
Remedy: Avoid overhead watering. Pick off diseased flowers. Spray at two weekly intervals with GroSafe Fungus Fighter.

 

Lack of fertiliser

Symptoms: Leaves yellow and/or develop dark purple tone. Slow, stunted growth
Remedy: Fertilise with Butlers Azalea, Camellia and Rhododendron food in late spring after flower finishes and just before new growth starts

 

Soil too alkaline

Symptoms: Decline in vigour and leaves turn yellow while the veins remain green
Remedy: Fertilise with Butlers Azalea, Camellia and Rhododendron Food in late spring after flowering finishes and just before new growth starts. Do NOT lime.

 

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