Dahlia

Pest & Diseases

 

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  Key to Dahlia

Pest & Diseases

 

    

       

                                              Flower problems

  1. Flowers and/or buds shrivelled and with fluffy grey Grey 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

                                            Foliage problems

 

  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

 

Red Spider Mite

  

 

  1. Leaves wilt; stem interior with brown or black streaks = Wilt

  2. Leaves with irregular holes and pieces eaten away with slime trails present on or near plants = Slugs and Snails

  3. Leaves with irregular holes and pieces eaten away; no slime trails present on or near plants = Caterpillars

  4. Leaves with small tattered holes, especially at tips of shoots; buds sometimes killed = Capsid Bugs

  5. Leaves, shoots and flowers infested by colonies of black, green or yellow wingless and winged insects; Foliage sticky and sometimes sooty =Aphids

  6. Stem with soft, irregular swelling = Crown Gall

  7. Stem base rotted; cottony white mould growth present = Sclerotinia Disease.

 

Picture illustrating virus.

The plants in the background are of the same cultivar.

 

 Powdery Mildew

 

 Picture illustrating sever Red spider attack

 

 Malformed Growth

(used bought Manure?)

Could it be Herbicide damage

from

aminopyralid

please use link

 

Dahlia Smut

 
   

Picture illustrating Crown Gall, here on a stored tuber although the tuber showed no physical signs until it began to shoot.

    

 

Dahlias from The National Dahlia Society.