Severe midge damage (SEVMDGE)
Severe midge damage is defined in the Official Grain Grading Guide.
Midge damaged kernels that are blackened by moulds are classed as severe midge damage. This discolouration is the result of a secondary fungal infection. Midge damaged kernels that have a grey or tan discolouration but are not blackened, are not assessed as severe midge damage. Severe midge damage is determined for Canada Western Amber Durum only.
Procedure for assessment
Severe midge damage is an objective grading factor.
To assess severe midge damaged samples, the inspector performs a physical separation to assess the percentage of these damaged kernels in the sample. The number of grams utilized to perform the assessment is predetermined and defined in the Official Grain Grading Guide. The inspector will then apply the tolerances for severe midge as set out in the Grade Determinant Tables found in the Official Grain Grading Guide.
Midge damaged kernels with a ruptured bran can be easily attacked by a secondary fungus causing the black discolouration.
The Orange Blossom Wheat Midge (Sitodiplosis mosellana) (Government of Alberta, Alberta Agriculture, Food and Rural Development) causes midge-damaged kernels. This pest is found in wheat-growing areas of Europe, Asia and North America. The orange fly deposits its eggs on the floret and then the hatching larvae feed on the developing grain.
Severely midge damaged kernels, which are blackened, presumably from attack by fungi, are particularly detrimental to semolina refinement and spaghetti color.
For more information on the affects of midge and severe midge damage and processing, access the following link to our Grain Research Laboratory papers on factors affecting processing performance of Durum wheat.
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