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Tar spot here to stay

Tar spot is expected to be a problem in areas where corn farmers have seen the pathogen in the past.

Mark Storr with BASF says crop diseases are hard to get rid of.

“Once the disease is in an area it essentially becomes a permanent resident, at least diseases like tar spot. Because what they do is they overwinter on disease tissue.”

He tells Brownfield the amount of pressure comes down to what he calls a “disease triangle.”

“You have to have the pathogen, which in this case is a fungal organism. You have to have the host, which in this case is corn. And you have to have the right environment, which we typically tend to think of as the weather.”

Storr says fungal organisms like tar spot require longer periods of leaf wetness to develop and points to late summer when heavy dews are common as a prime time for the onset of disease.