Foliar Diseases
For a larger view and narrative of each disease please click on the photo.
Photos provided by Tom Isakeit, Department of Plant Pathology, Texas A&M University.

BACTERIAL FRUIT BLOTCH - Causal Agent: (bacterium - Acidovorax avenae subsp. citrulli)

 


Note watersoaking of vein.

 
 
 
 
   
       

ANTHRACNOSE - Causal Agent: (fungus - Colletotrichum orbiculare)
     
   

GUMMY STEM BLIGHT - Causal Agent: (fungus - Didymella bryoniae)

 

note pycnidia (black)
  

DOWNY MILDEW - Causal Agent: (fungus - Pseudoperonospora cubensis)

ALTERNARIA LEAF SPOT - Causal Agent: (fungus - Alternaria cucumerina)

CERCOSPORA LEAF SPOT - Causal Agent: (fungus - Cercospora citrullina)

MYROTHECIUM LEAF SPOT - Causal Agent: (fungus - Myrothecium roridum)

POWDERY MILDEW - Causal Agent: (fungi - sphaerotheca fuliginea, Erysiphe cichoracearum)

LEAF MOSAIC - Causal Agent: (viruses - Watermelon Mosaic Virus, Papaya Ringspot Virus, Zucchini Yellow Mosaic Virus, Cucumber Mosaic Virus)

TOBACCO RING SPOT VIRUS

SQUASH LEAF CURL VIRUS

HERBICIDE INJURY - (2,4-D, or Dicamba)

Root & Vascular Diseases
For a larger view and narrative of each disease please click on the photo.
Photos provided by Tom Isakeit, Department of Plant Pathology, Texas A&M University.

FUSARIUM WILT - Causal Agent: (fungus - Fusarium oxysporum f. sp. niveum)


Vascular browning

YELLOW VINE - Causal Agent: (unknown, suspected to be a bacterium)


Phloem discoloration

SOUTHERN BLIGHT - Causal Agent: (fungus - Sclerotium rolfsii)

CHARCOAL ROT - Causal Agent: (fungus - Macrophomina phaseolina)

A water-soaked lesion develops around the crown of the plant, followed by the appearance of an amber-colored ooze at the surface. This area becomes dark brown, dried and cracked. Small black fungal structures (microsclerotia) are then formed in this area. A dark ring is visible beneath the outer layer when a cross section is cut through the canker. Infected plants have yellow leaves and die soon after symptoms are observed.

The damage is most severe when melons approach maturity. There are no effective controls for the fungus. Altering the irrigation program to prevent water stress may alleviate the problem.

 

MONOSPORASCUS ROOT ROT/ VINE DECLINE - Causal Agent: (fungus - Monosporascus Cannonballus)



Vascular discoloration

Root Lesions


Brown lesions on roots, Rhizoctonia and Pythium isolated

DAMPING OFF - Causal Agent: (fungi - Rhizoctinia solani, Pythium spp.)


Caused by Rhizoctonia solani

Caused by Pythium aphanidermatum

NEMATODES

NON-PATHOGENIC CAUSES


Seed corn maggot

Wilt caused by squash bug



Wilting caused by Trifluralin (herbicide) injury.
Note swollen area of stem

Death by lightning


Squash bug,
cause of anasa wilt
Glyphosate (herbicide) injury


Movement on plastic
 

Fruit Diseases
For a larger view and narrative of each disease please click on the photo.
Photos provided by Tom Isakeit, Department of Plant Pathology, Texas A&M University.

BACTERIAL FRUIT BLOTCH - Causal Agent: (bacterium - Acidovorax avenae subsp. citrulli)

ANTHRACNOSE - Causal Agent: (fungus - Colletotrichum orbiculare)

BACTERIAL RIND NECROSIS - Causal Agent: (bacterium - Erwinia spp.?)

BELLY ROT - Causal Agent: (fungi - several species)


Southern blight fungus
Pythium fruit rot
Pythium aphanidermatum

LASIODIPLODIA FRUIT ROT/ DIPLODIA STEM-END ROT - Causal Agent: (fungi - Lasiodiplodia theobromae)

PIMPLES - Causal Agent: (suspected virus - Tobacco Ring Spot Virus)


Ringspots

Necrotic, concentric rings

Pimples

BLOSSOM END ROT - Causal Agent: (physiological - water stress, calcium deficient)

BOTTLE NECK - Causal Agent: (physiological)

SUNBURN

FRUIT CRACKING/SCARRING


Animal damage
Physical scarring

SPLITTING - Splitting is caused by an erratic waterning pattern, particularly the excessive accumulation of water. The inside of the fruit is under great pressure and the fruit splits open when lightly tapped. The condition is weather related and there probably is a cultivar interaction as well.

CROSS STITCH

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