Weeds in Cereal Crop Rotations May Host <i>Fusarium</i> Species That Cause Fusarium Head Blight and Grain Weight Losses in Wheat

Fusarium Head Blight (FHB) is one of the most common worldwide wheat and other small grain diseases. The infection is caused by <i>Fusarium graminearum</i> and other related species, which significantly reduce grain yield and contaminate grains with mycotoxins which are harmful for humans and animals. <i>Fusarium</i> pathogen survives the winter well in plant debris left on the field. Weeds around and within crops are alternative hosts of <i>Fusarium</i> fungi when an economically important host plant is not present. This article focuses on the determination of DNA content of <i>Fusarium</i> species (<i>F. graminearum</i> and <i>F. avenaceum</i>) in artificially inoculated wheat plants with isolates from weeds, as well as its influence on the severity of FHB and spring wheat 1000-grain weight under field conditions. Fungal DNA content in grains was evaluated by quantitative real-time PCR. The results showed that the DNA concentration of <i>F. graminearum</i> was significantly higher in the grain than <i>F. avenaceum</i>. The severity of FHB when wheat heads were inoculated with <i>F. graminearum</i> was significantly higher than with <i>F. avenaceum</i>. All <i>F. graminearum</i> strains statistically significantly reduced the weight of spring wheat grains, while <i>F. avenaceum</i> did not affect the weight of 1000 grain. This investigation has shown that weeds in crop rotations are a potential source of FHB infection. However, the severity of the disease is more affected by the <i>Fusarium</i> species than the host plant. This experiment is, to our knowledge, the first report on the estimation of <i>Fusarium</i> DNA content in artificially inoculated wheat plants with isolates from weeds, as well as its comparison with pathogenicity to wheat and its effect on 1000-grain weight.