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Herbaceous Plants

   
             

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Last Modified: 01-Jun-2011
Copyright © 2004, University of Kentucky, College of Agriculture, Department of Plant Pathology
 
   

Plant: Lady's mantle (Alchemilla mollis) (Rosaceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Cercospora (fungus)
Signs: small dark spore-producing bodies ("conidiophores") and fine silvery threads which are the spores can be seen within the spots.
Symptoms: brown spots or blighted areas
Total image number: 4

     
 
     
                   

Plant: Pansy (Viola tricolor) (Violaceae) Back to List
Disease/Disorder: Black root rot
Causal agent: Thielaviopsis basicola (fungus)
Signs: dark, thickened spores called "aleuriospores" within root tissue.
Symptoms: Plants are stunted. Infected roots have areas of shrunken, darkened tissue.
Total image number: 4

     
 
     
                   

Plant: Daylily (Hemerocallis sp.) (Liliaceae) Back to List
Disease/Disorder: Rust
Causal agent: Puccinia hemerocallidis (fungus)
Signs: fungal pustules with yellow/orange spores
Symptoms: leaves start to yellow in sections and then the whole leaf
Total image number: 4
See information from the National Plant Board at http://www.aphis.usda.gov/npb/daylily.html

     
 
     
                   

Plant: Fern, Boston (Nephrolepis exaltata `Bostoniensis') (Pteridophyta) Back to List
Disease/Disorder: Root rot
Causal agent: Rhizoctonia (fungus)
Signs:
Symptoms: Plants are stunted with infected roots having areas of shrunken, darkened tissue.
Total image number: 4
The plant has had too much water and the roots are rotting due to the fungus, Rhizoctonia. Leaflets show what appears to be Potassium deficiency symptoms (light brown areas near the margin of the leaf or just inside the margin). The problem is not a potassium deficiency in the medium but a lack of enough healthy roots to take up required nutrients.

     
 
     
                   

Plant: Coneflower, purple (Rudbeckia purpurea) (Asteraceae) Back to List
Disease/Disorder: Yellows
Causal agent: a Phytoplasma (Phytoplasma)
Signs:
Symptoms: exhibit a symptom called "phyllody" which is the transformation of flower organs into structures like leaves.
Total image number: 6
Each row is a different plant sample

     
 
     
 
     
                     

Plant: Coneflower, sweet (Rudbeckia subtomentosa) (Asteraceae) Back to List
Disease/Disorder: Sclortinia stem rot, White mold
Causal agent: Sclerotinia sclerotiorum (fungus)
Signs: black survival structures called "sclerotia"
Symptoms: a dry stem rot usually with disintegrated pith tissue.
Total image number: 5
Note the hard, black survival structures called “sclerotia” in culture plates.

     
 
     
                   

Plant: Coreopsis (Coreopsis sp.) (Asteraceae) Back to List
Disease/Disorder: Downy mildew
Causal agent: Plasmopara halstedii (fungus)
Signs: white fungal growth on darkened infected portions of leaves
Symptoms: white fungal growth on darkened infected portions of leaves
Total image number: 4

     
 
     
                   
Plant: Chrysanthemum (Chrysanthemum sp.) (Asteraceae) Back to List
Disease/Disorder:
Root rot
Causal agent: Pythium sp. (fungus)
Signs: sexual reproductive spores ("oospores") seen in roots; look like hollow tires.
Symptoms: rotted roots
Total image number: 4
     
 
     
                   
Plant: Chrysanthemum (Chrysanthemum sp.) (Asteraceae) Back to List
Disease/Disorder:
Leaf spot
Causal agent: Pseudomonas cichorii (bacterium)
Signs: none
Symptoms: browned areas on leaves, mostly on margins
Total image number: 4
     
 
     
                   

Plant: Chrysanthemum (cultivar 'Lisa') (Chrysanthemum sp.) (Asteraceae) Back to List
Disease/Disorder:
Leaf spot
Causal agent: unknown
Signs: none
Symptoms:Leaves showed white tissue in areas on the margins and areas of white flecking located symmetrically on the leaves. A representative from Yoder Bros. said they call this the "Lisa problem". Yoder has done extensive virus/viroid testing over time and we have never been able to associate a virus or viroid. Likewise, they have done foliar and soil analyses and not been able to associate anything consistently. Also, they have never been able to associate spray injury, etc. Yoder sees this on 'Lisa' usually in the heat of the summer. The sunken white flecks are not apparent in cooler temperatures. Usually the crop grows out of it. After several years, this flecking symptom has not been considered a major problem for the chrysanthemum crop.
Total image number: 4

     
 
     
                   
Plant: Top Row, Petunia (Petunia hybrida) (Solanaceae) Back to List
Bottom Row, Marigold (Tagetes erecta) (Asteraceae)
Disease/Disorder:
herbicide injury, growth regulator injury
Causal agent: phenoxy herbicide.
Signs: none
Symptoms: Petunia (Top Row) shows root proliferation. Marigold (Bottom Row) shows galling (this is not Crown gall).
Total image number: 8
     
 
     
                   

Plant: Petunia (Petunia hybrida) (Solanaceae) Back to List
Disease/Disorder: iron deficiency or 'glyphosate-like' injury
Causal agent: iron deficiency or 'glyphosate-like' injury
Signs: none
Symptoms: Images from left to right - 1, 2, 3, 4
- 1st image has 4 views of 'glyphosate-like' injury
- 2nd image shows 'glyphosate-like' injury on top and iron deficiency symptoms on bottom
- 3rd image has 4 views with 2 views of 'glyphosate-like' injury on top and 2 views of iron deficiency on bottom
- 4th image has 4 views of iron deficiency
Total image number: 4


     
                   

Plant: Sunflower (Helianthus sp.) (Asteraceae) Back to List
Disease/Disorder:
herbicide injury, growth regulator injury
Causal agent: phenoxy herbicide
Signs: none
Symptoms: All the younger leaves in the sample showed symptoms of severe growth regulator
(i.e. phenoxy herbicides, e.g. 2,4-d) injury; curling, cupping, elongated tips or margins, and scalloped margins.
Total image number: 3

     
 
     
                   

Plant: Periwinkle, common (Vinca minor) (Apocynaceae) Back to List
Disease/Disorder: Root rot
Causal agent: Pythium and Rhizoctonia sp. (fungus)
Signs: none
Symptoms: Above-ground portions of plant dying back. Rotted roots
Total image number: 4
Looking at the root system it is easy to see that is where the problem lies. There were three fungi on the plants. Attacking the roots were Rhizoctonia and Pythium, and Fusarium was on some plant tissues above the soilless mix as a secondary organism. The presence of Pythium shows the roots are staying too wet as this fungus is one of the “water mold” fungi. Rhizoctonia can come in after any type of stress.

     
 
     
                     

Plant: Peony (Paeonia sp.) (Paeoniaceae) Back to List
Disease/Disorder: Anthracnose
Causal agent: Colletotrichum species (fungus)
Signs: raised, spore-producing bodies in rings within the stem cankers
Symptoms: dieback of flowers and stems
Total image number: 6

     
 
     
                     
Plant: Peony (Paeonia sp.) (Paeoniaceae) Back to List
Disease/Disorder: Blight
Causal agent: Phytophthora cactorum (fungus)
Signs: infected leaf tissue in water incubation allows sporangia of the fungus to form.
Symptoms: leaves, shoots, and flower buds are blighted
Total image number: 10
     
 
     
                     
 

Plant: Zinnia (Zinnia sp.) (Asteraceae) Back to List
Disease/Disorder:
Flower blight
Causal agent: Choanephora (fungus)
Signs: conidiophores (silvery threads of fungus) with conidia on an enlarged head
Symptoms: rotted flower petals
Total image number: 4
The flower is being infected by a fungus that more normally attacks squash fruit causing the disease called “Choanephora wet rot”. This fungus is listed as causing a flower blight disease on zinnia but it is noted as a problem seen more often in the deep south.

     
 
     
                     
  Plant: Iris (Iris sp.) (Iridaceae) Back to List
Disease/Disorder: Leaf spot
Causal agent: Mycosphaerella macrospora (fungus) Heterosporium iridis, imperfect stage seen
Signs: Dark fungal growth of Heterosporium iridis, the imperfect stage of the fungus, can be seen in the center of the spots.
Symptoms: oval spots with reddish-brown margins and gray centers appear anywhere on the leaf blade.
Total image number: 13
     
   
     
                     

Plant: Hollyhock (Alicea rosa) (Malvaceae) Back to List
Disease/Disorder: Rust
Causal agent: Puccinia malvaceorum (fungus)
Signs: On the underside of the leaf, 2-celled teliospores are borne singly on pedicels.
Symptoms: Yellow spots on the top surface of leaf and raised, orange structures on the bottom surface.
Total image number: 6


     
                     
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