1. OCCURRENCE OF FUSARIUM HEAD BLIGHT ON OATS IN BRAZIL AND EVALUATION OF DAMAGES José A. Martinelli Department of Fitossanidade Federal University of Rio Grande do Sul Brazil

2. How it looks like?

4. FHB on oats is a recent disease in Brazil and we believe it is a consequence of the no till system and the huge increase of inoculum.

5. However, there was not enough information about the losses that this disease may impose.

6. So, this work reports the potential loss it might cause on a number of genotypes under South American condition.

7. Layout: With fungicide With FHB Without fungicide Yield loss With fungicide Without FHB Without fungicide

8. Method: 15 genotypes tested Six plots each At flowering: 3 were treated and 3 untreated After, 150 panicles from each plot were marked with and without symptoms. In the Lab. each panicle was hand threshed having their healthy and diseased spikelets separated and weighted.

9. Main results: Effect of fungicide on panicle´s weight. Effect of FHB on panicles´ weight of treated plants. Potential Yield (PY). PY= weight of healthy spikelets/number of healthy spikelets*total number of spikelets (PY=WHS/NHS*TNS) Observed Yield (OY). OY = weight of healthy plus diseased spikelets (OY=HS+DS) Yield Loss (YL). YL = PY - OY

13. Concluding remarks FHB can cause a significant yield loss on oats. This effect is clearer on treated plots, probably due to the absence of other diseases, such as crown rust and leaf blight. So far, no resistance was found in the genotypes tested.

14. Many thanks, particularly to Prof. Marcelo Pacheco for this presentation. JAM is a member of the Oat Research Team, since 1992 and works mainly with crown rust.