Fusarium ear rot is a corn disease caused by the fungi Fusarium verticillioides, Fusarium proliferatum
and Fusarium subglutanins. In all three species the disease symptoms are similar, but only F.
verticillioides and F. proliferatum produce a group of mycotoxins called fumonisin which at high
enough levels can be toxic to animals, livestock, and humans.1 Fusarium ear rot can begin during
or after flowering (R1 growth stage) and is most problematic when with hot and dry weather is followed by periods
of high humidity. Rain before harvest may intensify the contamination of fumonisins in corn.
Due to health risks associated with fumonisin, grain must be tested to determine fumonisin levels. Management
practices can be implemented to help reduce the risk of Fusarium in future corn crops.
Infected kernels have a white-to-pink cottony mold which are scattered around the ear (Figure 1).
Figure 1. Fusariun infected kernels scattered around the ear
Infected kernels may have white streaks that are arranged in a starburst pattern (Figure 2). The mold can produce
a mycotoxin called fumonisins.
Figure 2. Starburst pattern of Fusarium infected kernels
Sampling and Testing Procedures
If Fusarium ear rot is suspected, scout fields at physiological maturity (R6 growth stage) to determine the
severity.1 If the ear rot is widespread, harvest as early as possible to reduce the level of fumonisin
contamination and ear rot damage to kernels. At harvest grain must be tested to determine the level of fumonisin
as toxin levels are not synonymous with visible ear rot symptomology. Fumonisin can be detected in a kernel that
does not have any damage to the seed coat (pericarp). In order to know if a cornfield is impacted by mycotoxins,
testing can be completed by an elevator with testing capabilities, grain exchanges, or an approved independent
Fumonisin does not occur uniformly in bulk corn, and grain handlers should sample in several areas of a load or
bin. Contact a toxicology laboratory for specific sampling, handling instructions and analysis. There are a
variety of commercial laboratories and quick-test kits for mycotoxin analysis. Actlabs Agriculture (email@example.com) and Agribrands Purina are two of many that
do fumonisin testing.
A farmer with fumonisin contaminated grain has some options; however, discounted prices are likely if the
milligrams per kilograms (mg/kg) levels reach a high level. If fumonisin contaminated grain is being used to make
ethanol, the ethanol fermentation process increases the mycotoxin concentration levels in the distillers dried
grain (DDG). Experiments have evaluated the mycotoxin concentrations in DDGs and have reported to be approximately
three times as high as the level in the grain. Moulds can grow and mycotoxins can be produced in DDGs during
transport, storage, and feeding at the farm which can further increase the fumonisin levels and danger when fed.
Table 1. Recommended tolerance levels (mg/kg) of several mycotoxins in Canada and the USA
According to a report by the Government of Canada, 2010-2011 Fumonisins in Corn Products, there are no Canadian
maximum levels, tolerances, or standards for fumonisins in corn products .2
Corn Product Selection and Management
Corn product selection is an important step in managing fusarium outbreaks in corn. Products with insect
resistance traits (above ground Bt protection), drought tolerance, and downward position ears at maturity
can help reduce the potential production of mycotoxins. Corn products with insect resistant traits
(Trecepta® Technology) that protect the ear from corn earworms and Western bean cutworm may have lower
levels of ear moulds as insect feeding can create additional pathways for the disease to infect the kernels.
Fumonisin can be detected in a kernel that does not have any damage to the seed coat (pericarp). Other factors
that may influence fumonisin contamination are environmental conditions during two periods of corn development.
The tasseling growth stage (R1) and physiological maturity (R6), are critical growth stages for kernel
contamination with fumonisin.1 Contact your local agronomist to select the best locally adapted corn
products with proven disease tolerance or resistance.
Fungicide seed treatments can help protect young plants and reduce the buildup of fusarium pathogens in the soil.
Optimize soil fertility to aid in plant health and improve residue decomposition. Avoid high levels of nitrogen
and low levels of potassium.
Management to Minimize Mycotoxin Contamination
Some management practices can help to minimize mycotoxin contamination. These include:
- Limiting bird and insect damage, because moulds tend to invade damaged kernels more easily than intact ones.
- Harvesting grain as soon as possible. Fusarium mould grows readily under warm, damp conditions.
- Adequate drying and storage of grain to prevent mould growth and mycotoxin production post-harvest.
Once corn dries down to 17% moisture, ear rot caused by Fusarium should cease development. Store grain
at cool temperatures 2 to 6.5 0C (36 to 44 0F). Stored grain should be checked
periodically for temperature, wet spots, and insects.
- High moisture corn should be checked to ensure that ensiling conditions remain anaerobic to limit mould growth
and mycotoxin contamination. Moulds cannot grow under truly anaerobic conditions.
- Using crop rotation to minimize the carry-over of moulds from one year to the next. Fusarium survives on crop
residue. If corn-on-corn rotations are used, then crop residue should be completely buried so that
pathogens will have the least chance of survival. Tillage operations that only partially bury residue, such
as chopping, disking, or chiseling, are also beneficial for pathogen reduction.
- Avoiding planting crops that may be susceptible to mould infestation in adjacent fields where the disease may
spread from one crop to the other.
- When contamination does occur, mould spores and mycotoxins are often concentrated in the fines and dust of
grains. Use of masks to avoid inhalation and ingestion of dust by grain handlers is recommended.3
Steps for Dealing with Mycotoxins
If a corn field is suspected to have high levels of fumonisin, testing must be completed by elevators, grain
exchange, or approved independent laboratory facilities.
Farmers that suspect fumonisin contamination should:
- Inform crop insurance provider of suspected issue prior to harvest or storage.
- Insurance adjuster must collect samples prior to grain entering storage.
- Only Approved Insurance Provider (AIP) Testing Facilities can complete analysis of corn samples.
Farmers with questions regarding handling protocol should contact their insurance provider.
1 Kamle, M., Mahato, D.K., Devi, S., Lee, K.E., Kang, S.G. and Kumar, P. 2019. Fumonisins: Impact on
Agriculture, Food, and Human Health and their Management Strategies. National Center for Biotechnology
2 Diaz-Royon, F. 2016. Mycotoxins are concentrated in distillers grains. Hoard’s Dairyman. December
3 Charmley, L.L., and Trenholm, H.L. 2017. Mycotoxins in livestock feed Guidance Document. AgReTech.
Repository (GDR) RG-8 https://inspection.canada.ca/animal-health/livestock-feeds/regulatory-guidance/rg-8/eng/1347383943203/1347384015909?chap=1#fn1
4 2018. 2010-2011 Fumonisin in corn products. Government of Canada. https://inspection.canada.ca/food-safety-for-industry/food-chemistry-and-microbiology/food-safety-testing-bulletin-and-reports/2010-2011-fumonisins/eng/1349817198567/1349817962653
Web sources verified 04/23/2021.
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should consider the impacts of these conditions on the grower’s fields.
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