OCCURRENCE OF FUSARIUM HEAD BLIGHT ON OATS IN BRAZIL AND

EVALUATION OF DAMAGES

José A. MartinelliDepartment of Fitossanidade

Federal University of Rio Grande do SulBrazil

How it looks like?

How it looks like?

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.

However, there was not enough information about the losses that this

disease may impose.

So, this work reports the potential loss it might cause on a number

of genotypes under South American condition.

Layout:

With fungicide

With FHB

Without fungicide

Yield loss

With fungicide

Without FHB

Without fungicide

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.

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

Table 1. Effect of fungicide on the weight of panicles.

Treatment Weight of panicles (g)*

With fungicide 2.299 a

Without fungicide 2.149 b

C.V. = 10,77%

* Tukey at 5% of probability.

TABLE 2. Potential Yield, Observed Yield and Yield Loss of FHB

(g/panicle) on oats, with and without fungicide.

Fungicide Treatment

Potential Yield

Observed Yield

Yield Loss

% of YL*

With

2 .154 a 2.092 a 0 .061 a 2 .83

Without

2 .004 b 1.938 b 0 .066 a 3 .29

% redu ction 6.96 7.63

C.V. (%) 11 .80 12 .19 24 .54

Mea ns we re compare d by Tuke y a t 5% of probability. * In re lation to the Pote ntia l Yie ld.

TABLE 3. Effect of FHB on panicles´s weight of treated plants.

Treatment Weight of panicle (g) *

% of reduction

Without FHB

2.507 a

With FHB

2.092 b 16.5

C.V. =10.04%

* Tukey at 5% of probability.

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.

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.