True Loose Smut in Your Wheat

True loose smut is a fungal disease that begins within the seed. It has little to no signs or symptoms until heading out occurs and can cause unsurmountable economic losses depending on the rate of infection. Grain grown with smut infected seed is considered empty grain for it will have no worth.

True loose smut in wheat turns the heads into a black dusty spore mass. These spores can be released very easily because spores are covered by a delicate membrane which can be broke by wind, rain or anything brushing against it such as wildlife. The florets are completely destroyed and once the spores are all released all that is left is the bare spike of the head which may look distorted. Once spores are released they can infect other plants. Seed will not show infection until the following year when seeds germinate.

This disease has a two year life cycle. It overwinters in the seed embryo, which makes it hard to detect. Infected seed shows little to no difference between itself and healthy seed. The only sure way to confirm seed health before seeding is by submitting a sample to a lab such as 20/20 for testing. Once the seed germinates the fungus is activated and makes its way through the plant to the growing points. The infection rate is based on how cool and moist it is in July because it slows the flowering period which allows more of the spores to get into the head and infect the seed. Therefore seed production for following year is compromised.

There aren’t many ways to control true loose smut once seed is already infected in the crop. There are no fungicides that can counteract the infection once it is seen in the crop since the disease began at seed germination. The best control for true loose smut would be to grow a smut resistant variety or to use certified seed. A systemic seed treatment could also prove to be a way to help control true loose smut. True loose smut doesn’t overwinter in soil nor is it soil borne so using healthy seed is a perfect way to avoid tremendous yield loss.

How 20/20 Seed Labs does a test for True Loose Smut:

This test is done over a period of three days as it is such a in depth test. Over 1000 embryos of seed are extracted then acid and stain are added to show if there is fungus within the embryo or not. Then, 400 embryos are examined by a technician to see if there is a certain type of mycelium called Ustilago tritici; which is the Latin name of the disease causing fungus in wheat. The percentage of infected embryos is at 0.25%.

 

http://www.2020seedlabs.ca/what-causes-true-loose-smut-wheat-and-barley ;20/20 Seed Labs Inc.

 

http://www.seedtesting.com/analyzing-your-results/testing-for-disease/smut/ ;Discovery Seed Labs Ltd.