Fusarium fungi on harvested maize can be lethal to horses

High rainfall can lead to bumper maize crops, but it can also cause rapid growth of mycotoxins, which are harmful to broodmares, says Dr Mac.

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Heavy rainfall over the past few months has resulted in wet, muddy conditions that are favourable to the development of fungal toxins, which may be deadly to horses.

Many horse breeders and owners move their riding horses and broodmares onto harvested maize lands, not only because the veld and planted pastures have been grazed to their roots, but also because farmers often offer ‘free grazing’ when they clear their lands for planting. This is often seen in KwaZulu-Natal and the Eastern Cape, where thoroughbred broodmares are moved onto harvested maize lands in May.

This year, rains have soaked the land, and the high carbohydrate content of maize cobs will have increased the possibility of certain fungal moulds that are highly toxic to horses.

Fumonsins are the generic name for the toxins produced by the fungus Fusarium verticillioides, which grows rapidly in maize residues on harvested fields, especially in hot, wet weather.