Key to Dahlia Pests & Diseases

Problems with Flowers

1. Flowers & / or buds shrivelled and with fluffy white mould = Botrytis.
   
   
2. Flowers with mass of mites covering bloom (Generally seen when bloom brought into the House for decoration purposes) = Red Spider
   
3. Flowers with tattered petals = Earwigs 
   
   
4. Flowers with light flecking on petals, many small long-bodied winged and wingless insects’ present = Thrips
   
5. Flowers with irregular holes and pieces eaten away and slime trail present = Slugs and Snails
   
6. Flowers with  holes (Centre of bloom) and petals with pieces eaten away; no slime trails present on or near flower = Caterpillars

Problems with Foliage

1. Leaves with numerous pale spots = Smut
   
2. Leaves with white dust like covering = Powdery Mildew
   
3. Leaves variously crumpled with irregular, pale yellowish patterns with insects visible more so with a magnifying glass = Red Spider
   
4. Leaves variously crumpled with irregular, pale yellowish patterns with no insects visible with a magnifying glass = Virus
   
5. Leaves wilt; stem interior with brown or black streaks = Wilt
   
6. Leaves with irregular holes and pieces eaten away with slime trails present on or near plants = Slugs and Snails
   
7. Leaves with irregular holes and pieces eaten away; no slime trails present on or near plants = Caterpillars
   
8. Leaves with small tattered holes, especially at tips of shoots; buds sometimes killed = Capsid Bugs
   
9. Leaves, shoots and flowers infested by colonies of black, green or yellow wingless and winged insects; Foliage sticky and sometimes sooty =Aphids
   
10. Stem with soft, irregular swelling = Crown Gall
    
11. Stem base rotted, cottony white mould growth present = Sclerotinia Disease