Argentine researchers find Drechslera tritici-repentis resistant to strobilurins fungicides

 

The fungus Drechslera tritici-repentis, which causes the disease popularly known as yellow spot of the wheat leaf, may be developing resistance to strobilurins, which are fungicides that react with lipid substances on the plant surface. According to Marcelo Carmona, professor and researcher at the Faculty of Agronomy at the University of Buenos Aires, this theory is still being researched.

 

"Currently there is a hypothesis, which we are trying to confirm in the Faculty of Agronomy, of cases that we are encountering in fields of applications where the fungicide is not working. We believe it may be, but we have no scientific confirmation yet," said Carmona.

 

According to Carmona, it is much easier to analyze this type of case when the product is a herbicide or insecticide, in which both the producer and the agronomist can visibly identify the aggressor populations. In the case of Drechslera tritici-repentis, as it is a fungus, he said that any application should be made based upon studies of plant symptoms, rather than on a pattern of behavior.

 

"However, we always mean that treating diseases according to phenology is a wrong technique, because diseases do not always respond in the same way, instead they show symptoms and this is the way that the producer can directly quantify the population of fungi, "he added.

 

Carmona notes that small doses, or divided doses, are not effective. "We have to make decisions based on studies, and not divide the doses as we were doing, because dividing the dose gives twice as long of a period for those pests that are becoming resistant and then have the chance to multiply their population," he said.