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GrainGenes Pathology Report: Black Point

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Pathology
Black Point
Other Name
Kernel Smudge
Smudge
Kernel Blight
Type
Fungus
Host Species
Triticum aestivum
Hordeum vulgare
Causal Organism
[ Hide all but 1 of 20 ]
Alternaria alternata
Bipolaris sorokiniana
Cladosporium spp.
Cladosporium cladosporioides
Cochliobolus tritici
Curvularia lunata
Curvularia pallescens
Nigrospora sphaeria
Penicillium spp.
Pyrenophora graminea
Pyrenophora teres
Rhizoctonia spp.
Rhizopus spp.
Alternaria spp.
Fusarium spp.
Helminthosporium spp.
Cochliobolus sativus
Curvularia spp.
Stemphylium spp.
Chaetomium spp.
Symptoms
Black point describes the discolored appearance of harvested grain infected by fungi during kernel development. Infection is favored by humid field conditions (>90% relative humidity) while kernel moisture content exceeds 20%. Severity can increase for infected grain stored under humid conditions. Severe infections often reduce seed germination levels. Kernels darkened by black point fungi are considered damaged by USDA-FGIS grain grading standards with only 2 and 4 percent damaged kernels permitted in US No. 1 and No. 2 grades, respectively. Black point is more prevalent under irrigated than dryland conditions.
Image
Soft white wheat kernels discolored by...
Conidiophores of Alternaria species (50x).
Conidia of (wild) saprophytic Alternaria species (10x40).
Larger conidia of Alternaria triticina (10x40)...
Reference
ReferenceKephart KD (1993) Winter wheat disease management Insect and plant disease management handbook.
Reference(1987) Compendium of wheat diseases.
Reference(1982) Compendium of barley diseases.