31 Pork News & Views Pork News & Views Ontario Ministry of Agriculture, Food and Rural Affairs Better Pork | December 2023 nued ear mould activity until grain moistures or temperatures drop enough to limit activity. Feeding damage Ear feeding by pests, particularly western bean cutworm (WBC), corn earworm (CEW) or birds can open husks and damage kernels which present opportunities for greater ear mould infection and DON. While still only representing a minority of samples, feeding damage appeared more common than what has been observed in recent surveys. Peak WBC moth flights generally occurred towards the very end of July through the first full week of August, generally coinciding with the latter half of tasseling in many areas. Where feeding damage was present, visual mould symptoms were usually more apparent. How to Sample Corn Loads The importance of collecting representative samples cannot be emphasized enough. Significant variability in mycotoxin testing results can come from poor sampling. Collecting a bulk sample from a corn load While sampling from the top of a storage bin, truck or combine may be convenient, mycotoxins are rarely distributed evenly in grain loads, hence a sample probe is recommended. The more probes the better, but Ontario research shows that 4 probes sampling the full depth of wagons or trucks can do as good of a job representing corn loads as frequent tailgate sampling (swiping stream). Probes are not the major driver of variability experienced with DON testing. For moving grain streams, use a diverter or randomly collect cups of grain. Mix all collected probes/ samples into one bulk sample of at least 2 kg. Collecting an analysis subsample from a bulk sample Ontario research shows that one of the most significant sources of variability in DON testing comes from collecting the subsample for DON analysis (e.g. the amount of the 2kg bulk sample that is finely ground for the DON test). Because individual kernels can be highly variable in DON and still coarse in size relative to the analysis subsample (e.g. a 200g whole kernel sample used for fine-grinding may be representing the entire load with only 500 kernels), the whole bulk sample should be ground (at least coarsely) and mixed so the analysis subsample contains parts of all kernels in the bulk sample. This subsample can then be ground finer to meet specifications of the DON test. Remember, samples must be processed quickly – ship or deliver fresh samples promptly. The longer the sample sits around the greater potential for inaccurate results. Going forward This survey does not capture all regions of the province and results can vary from field to field depending on local weather, hybrid, planting date, insect feeding, rotation, residue levels, fungicide practices and moisture. Results may not capture what is occurring in your field, therefore monitoring is always recommended. Timely harvest is important. Leaving infecFigure 2: Corn ear mould and deoxynivalenol (DON) survey sampling locations and results in 2023.
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