Timing of susceptibility to Fusarium head blight in winter wheat

Authors: Cowger, Christina; BECCARI, GIOVANNI - University Of Perugia; DONG, YANHONG - University Of Minnesota

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2020
Publication Date: 5/12/2020
Citation: Cowger, C., Beccari, G., Dong, Y. 2020. Timing of susceptibility to Fusarium head blight in winter wheat. Plant Disease. https://doi.org/10.1094/PDIS-03-20-0527-RE.
DOI: https://doi.org/10.1094/PDIS-03-20-0527-RE

Interpretive Summary: How long wheat is susceptible to Fusarium head blight (FHB) has implications for risk forecasts, the timing of fungicide applications, and whether visible kernel damage is a good predictor of deoxynivalenol (DON) contamination. A field experiment was carried out for four years (2010-2013) in North Carolina to explore the impact of different infection timings on Fusarium head blight development in winter wheat. The trials used a susceptible wheat variety and a moderately resistant one with similar maturity, stature, and grain quality. Spores of the fungus Fusarium graminearum were sprayed on the plots to cause FHB. The nine infection timings were from 0 to 21 days after early flowering the first year, but from 0 to 13 days after early flowering in the following three years. The development of infections was tracked by sampling heads 5 to 6 times during grain-fill. The moderately resistant variety had at least a 2- to 3-day shorter window of susceptibility to damaging FHB infection than the susceptible variety. How long wheat is susceptible appears to be an important aspect of resistance to FHB. In 2012, the window of susceptibility for both varieties was apparently lengthened by cold snaps during flowering. While the majority of DON was in the bran portion of kernels in one year, our data suggest that later infections may lead to a higher percentage of DON in the non-bran fraction, from which refined flour is made.

Technical Abstract: The duration of wheat susceptibility to Fusarium infection has implications for risk forecasting, fungicide timing, and the likelihood that visible kernel damage may under-predict deoxynivalenol (DON) contamination. A field experiment was conducted to explore the impact of varying infection timings on Fusarium head blight development in winter wheat. Trials in four successive years (2010-2013) in North Carolina utilized one susceptible and one moderately resistant cultivar possessing similar maturity, stature, and grain quality. Inoculum was applied in the form of sprayed Fusarium graminearum conidia. In the first year, the nine infection timings were from 0 to 21 days after early anthesis (daa), while in the following three years, they ranged from 0 to 13 daa. Infection progression was compared among inoculation timings by sampling 5 to 6 times during grain-fill. Based on DON, kernel damage and infection, and fungal spread as assayed via q-PCR, the moderately resistant cultivar had at least a 2- to 3-day shorter window of susceptibility to damaging Fusarium head blight (FHB) infection than the susceptible cultivar. The results suggest that duration of susceptibility is an important component of cultivar resistance to FHB. In 2012, the window of susceptibility for both cultivars was apparently extended by cold snaps during anthesis. While the majority of DON was in the bran fraction of kernels after debranning samples in one year, our observations are also consistent with later infections leading to a higher percentage of DON in the non-bran fraction, as well as a higher ratio of DON to FDK.