Acta agriculturae Slovenica, 87 - 2, september 2006 str. 381 - 391 
Agrovoc descriptors: bread, breadmaking, quality, baking, mildews, doughs, 
stability, keeping quality 
 
Agris category code: Q03, Q04 
 
COBISS Code 1.01 
 
Effect of powdery mildew attack on quality parameters  
and experimental bread baking of wheat 
 
Vesna SAMOBOR
1
, Marija VUKOBRATOVIĆ
2
 and Marijan JOŠT
3 
 
Received: August 16, 2006; accepted: August 28, 2006. 
Delo je prispelo 16. avgusta 2006; sprejeto 28. avgusta 2006. 
 
ABSTRACT 
 
The research of powdery mildew impact on bread making quality of wheat was conducted on 
seven divergent wheat cultivars/lines, in factorial treatment designs (T
0 
- untreated and T
1
 - 
with fungicide Duett treated variants) at Križevci, Croatia. Test weight, grain protein content, 
wet gluten, sedimentation value and rheological parameters, as well as experimental bread 
baking were examined during two years (2000 and 2001). 
 
Two years average test weight and grain protein content readings are significantly lower at 
untreated (T
0
) variants (diff. = 1.01 kg/hl** and 0.5 %** respectively). In wet gluten content 
there was no significant difference between the two variants, while average sedimentation 
value was significantly higher at untreated (T
0
) variant (diff. = 2.6 ml**). Farinographic 
indicators of quality (dough development and stability, resistance, degree of softening) as well 
as indicators of extensograph (energy and resistance) were also better at untreated (T
0
) 
variants.  
 
Dough yield, one of test-baking parameters, was bigger in treated (T
1
) variants, while the 
volume contribution was higher in untreated (T
0
) variants. Contrary to expectations, untreated 
resistant, moderately infected, or even susceptible variants had better quality parameters, 
offering speculation about eventual negative side-effect of applied fungicide Duett 
(epoxiconazole 12.5% + carbendazim 12.5%). Due to an interaction between numbers of 
different factors the speculation should be additionally checked and revised.  
 
Key words: wheat, powdery mildew, bread baking quality. 
 
IZVLEČEK 
  
VPLIV OKUŽBE S PEPELASTO PLESNIJO PŠENICE NA DEJAVNIKE KAKOVOSTI IN 
REZULTATE POSKUSNE PEKE KRUHA  
   
V Križevcih (Hrvaška), je dve leti (2000 in 2001) potekal poskus s sedmimi sortami/linijami 
pšenice v faktorskem poskusu (T
0 
– netretirana in T
1
 – s fungicidom Duett tretirana varianta) 
za raziskavo vpliva okužbe s pepelasto plesnijo na kazalce pekovske kakovosti pšenice 
                                                 
1
  Dr. Sc.   -  College of Agriculture Križevci, M. Demerca 1, 48260 Križevci, Croatia 
2
  B. Sc.agr., lecturer 
3
  Dr. Sc.,  Prof. 
 

Acta agriculturae Slovenica, 87 - 2, september 2006 
 
382 
(hektolitrska masa, vsebnost beljakovin in  vlažnega glutena, sedimentacijska vrednost, 
reološki parametri in rezultati poskusne peke kruha). Povprečna hektolitrska masa in 
vsebnost beljakovin sta bili značilno nižji pri netretiranih (T
0
) variantah (razlike = 1,01 kg/hl** 
in 0,5 %**). Glede na vsebnost vlažnega glutena ni bilo značilnih razlik med proučevanimi 
variantami, medtem ko je bila ugotovljena povprečna vrednost sedimentacije značilno višja pri 
netretiranih (T
0
) variantah (razlika = 2,6** ml). Farinografski pokazatelji kakovosti (razvoj 
testa, stabilnost, odpor, stopnja mehčanja) kot tudi pokazatelji ekstenzografa (energija in 
odpor) so bili ugodnejši pri netretiranih variantah. Pri poskusni pripravi kruha in peki je bil 
nastanek testa večji pri tretiranih (T
1
) variantah, medtem, ko je bil volumen kruha večji pri 
netretiranih (T
0
) variantah. V nasprotju s pričakovanji so imele na pepelasto plesen odporne, 
delno občutljive in občutljive pšenice boljše parametre kakovosti, kar omogoča sklepanje o 
možnem stranskem negativnem učinku fungicida Duett (epoxiconazol 12.5% + carbendazim 
12,5%). Zaradi kompleksnih interakcij številnih dejavnikov vključenih v uravnavanje teh 
mehanizmov, bi bilo potrebno ta rezultat še dodatno raziskati in preveriti. 
 
 Ključne besede: pšenica, pepelasta plesen, pekarska kakovost. 
 
 
 
1 INTRODUCTION 
 
Improved agronomic practices in wheat production, primarily higher population 
density and higher nitrogen application, created favorable conditions for pathogen 
development and higher crop sensitivity to diseases. Powdery mildew of wheat 
(Erysiphe graminis D.C. f.sp. tritici E. Marchal; synonym = Blumeria graminis D.C. 
f.sp. tritici March.) is a common disease in northwest region of Croatia. Its negative 
impact on grain yield is well documented. Depending on severity and time of attack 
powdery mildew reduce supply of photosynthesis and nitrogen re-translocation from 
leaves, negatively affects development of root system and leaf assimilation on area, 
affects all three yield components, and finally the grain yield (Fried et al., 1976; 
Carver and Griffiths, 1981; Gair et al., 1983; Kišpatić, 1984; Bowen et al., 1991; 
Henry and Kettlewell, 1996; Cvjetković, 2003; Samobor et al., 2005; etc.). According 
to time and severity of disease attack, the extent of yield losses can be predicted 
mathematically (Large 1954, Large and Doling 1962, 1963, Johnson et al., 1979).  
 
Strong attack of powdery mildew has negative impact on test weight and thousand 
kernel weight (Bowen et al., 1991, Samobor et al., 2005). There are a few data 
available about mildew impact on other bread making quality parameters, and some 
information are even conflicting. Flour yield is related to test weight.  Everts et al. 
(2001) report reduced flour yield of soft wheat cv. Saluda in the presence of powdery 
mildew infection. Lower amount of grain protein and resulting increase quality of soft 
wheat cv. Chancellor was reported by Johnson et al. (1979). More recently, increased 
level of grain protein and lower bread making quality of bread wheat was reported 
(Gooding et al., 1994), and also in cool, wet weather pre-maturity α-amylase activity 
can be reduced as a result of faster grain drying and faster crop senescence. 
 
As a result of mutations and gene recombination during sexual phase of reproduction 
in fungus Erysiphe graminis the number of virulent physiological races/pathotypes 
are increasing permanently. The physiological race/pathotype is a genotype of 
pathogen that attacks only certain group of cultivars (Niks et al., 1993); or the 
race/pathotype is defined as a segregant of pathogen, that provokes different reactions 
within host genotypes (Fehr, 1987). But reports about race/pathotype related effect of 

SAMOBOR, V. et al: Effect of powdery mildew attack on quality parameters … 
 
 
 
383
disease attack on wheat quality was not found. In Croatia, the identification of 
races/pathotypes started in1960’s. At the beginning only 18 virulent races/pathotypes 
were determined (Špehar, 1968), while in 1990’s number of races reported for regions 
of northwest Croatia and Slovenia increased to 61 (Korić, 1991 and 1994). Races 46, 
51, 75 and 85 with 6-10 virulent genes were reported as the most common and the 
most virulent. Today 48 genes for resistance to powdery mildew located on 32 loci 
and 16 different chromosomes are determined (Xiu-Quiang and Röder, 2004) but 
there were no reports about its pleiotropic effect on bread making quality.   
 
The purpose of this research was to determine the effects of powdery mildew 
(Erysiphe graminis D.C. f.sp. tritici) attack on parameters of wheat (Triticum 
aestivum ssp. vulgare) bread-making quality.  
 
 
2   MATERIALS AND METHODS 
 
Based on earlier investigations (Samobor and Jošt, 1999; Samobor et al. 2005) seven 
divergent wheat cultivars/lines were selected  (Tab. 1) and tested during two years (2000-
2001) at Križevci (46
0
 01' N – 16
0
 32' E), Croatia. The two factorial randomized block design 
were used including untreated -T
0
 and with fungicide Duett treated -T
1
 variants. Fungicide 
treatment at T
1
 variants were performed once in 2000, and twice in 2001: at steam elongation 
and before heading (Feekes-Large scale 6-8 and 10.1). Only the two very susceptible 
cultivars (Žitarka and Široka) were treated three times in 2001. The final reading of disease 
attack was done at heading (Feekes-Large scale 11). 
 
The intensity of disease attack was measured on Brooks scale (1-5) and height of infection on 
Saari-Prescott scale (0-9). Besides the powdery mildew attack, test weight, grain protein 
content, wet gluten content, sedimentation value, rheological parameters and experimental 
baking were determined on both untreated, infected (T
0
) and treated, protected  (T
1
) variants. 
The readings for each year, and two years average are presented in tables. 
 
Table 1.  Origin and some characteristic of selected cultivars/lines 
 
No. Cultivar/line Origin HMW glutens Remark 
1     KS92WGRC21 USA N    7+9   5+10 Resistant, good quality 
2  Divana Croatia 2*  7+9   5+10 Tolerant, very good quality 
3     4572.07 New Zealand N    7+9   5+10 Tolerant, acceptable quality 
4     Droria Romania N   7+8   5+10 Susceptible, good quality 
5  C00223 Argentina  1    7+9   5+10 Susceptible, good  quality 
6  Žitarka Croatia 1    7+8   2+12 Susceptible, accept. quality 
7     Široka Croatia 1    7+9   2+12 Very susceptible, low quality
 
 
3   RESULTS AND DISCUSSION 
 
The bread-making quality of wheat is a complex character that can be defined by 
many parameters; all of them are in interaction with the environmental factors 
(genotype vs. macro and micro nutrients availability, climate, severity of diseases 
attack, crop yield, etc.).   
 
In the year 2001, due to more humid climatic conditions (795.0 mm rainfalls), the 
powdery mildew attack was a little stronger, while the year 2000 was rather dry 
(565.9 mm rainfalls) with low disease severity.  

Acta agriculturae Slovenica, 87 - 2, september 2006 
 
384 
A) Intensity of disease attack 
0
1
2
3
4
5
Brooks scale (0-5)
T0 T1
B) Height of attack
0
2
4
6
8
KS92WGRC21
4572.07
DIVANA
C00223
DRORIA
ŽITARKA
ŠIROKA
Saari-Prescott (0-9)
 
Fig. 1.  Powdery mildew attack: intensity (Brooks) and height (Saari-Prescott) for 
seven cultivars/lines grown at Križevci, in 2001 
 
The powdery mildew attack for seven divergent cultivars/lines grown in 2001 was 
shown in Fig.1. Only line KS92WGRC21 was completely resistant in both years of 
research. Other entries could be classified as tolerant (Divana and 4572.07), 
susceptible (Žitarka, C00223, Droria) and very susceptible (Široka). Differences 
between untreated (T
0
) and with fungicide treated (T
1
) variants were highly 
significant. (Tab.2) 
 
Test weight and grain protein content are common and at elevators widely used 
parameters of wheat grain quality. Treated variants (T
1
) had significantly higher 
average test weight and grain protein content, but in wet gluten content there was no 
significant difference between the two variants (T
1
 and T
0
). (Tab.2)  However, 
sedimentation value, as the more valuable parameter of wheat bread baking quality, 
had opposite readings.  
 

SAMOBOR, V. et al: Effect of powdery mildew attack on quality parameters … 
 
 
 
385
Table 2.  Differences in average readings of powdery mildew (E. graminis ssp. 
tritici) attack and quality parameters between T
0  
and T
1  
of seven wheat 
cultivars/lines, grown at Križevci in two years (2000 and 2001) 
 
No.   Parameter Treatment ** 2000 2001 Average  Difference ***
  Powdery mildew attack  T
1 
1 , 1 1 , 1 1 , 1 
1 
  (Brooks, Saari-Prescott)* T
0 
2 , 3 3 , 6 3 , 5 
>   2**, 4 ** 
T
1 
82.50 79.78 81.14 
2    Test weight  (kg/hl) 
T
0 
81.64 78.62 80.13 
>    - 1.01 ** 
T
1 
12.43 13.99 13.21 
3   Grain protein content (%) 
T
0 
12.10 13.66 12.88 
>    - 0.33 ** 
T
1 
23.99 26.39 25.19 
4   Wet gluten content (%) 
T
0 
24.00 26.14 25.07 
>    - 0.1     
T
1 
45.93 43.09 44.51 
5   Sedimentation value (ml) T
0 
48.20 45.94 47.07 
>      2.6 ** 
* 
Attack intensity (Brooksu 1-5), height of infection (Saari-Prescott 0-9) 
** T
1
 = treated with fungicide Duett, T
0
 = untreated 
*** 
Significant difference at  p=0.05 (*)  and  p=0.01 (**) 
 
Significantly higher average value was in untreated (T
0
) variant (diff. = 2.6** ml). 
While grain protein content tells us about amount of proteins, sedimentation value 
tells us more about protein quality, and this fact can explain the sudden changes. This 
is confirmed by farinographic indicators of quality. Only average water absorption 
was higher in treated variant (T
1
), because it depends upon the amount of protein. 
While all other indicators, except of course - degree of softening which is negatively 
correlated with bread making quality, had higher values in untreated (T
0
) variants 
(dough development time, stability, resistance and quality numbe r ) . T w o o f 
extensigraphic parameters (energy and resistance) were also better in untreated (T
0
) 
variants, while extensibility is higher in treated (T
1
) variant. (Tab.3; Figs. 2 and 3). 
 
Amylolitic activity measured by Hagberg-Pertten falling-number or by amylograph 
was generally slightly higher in treated (T
1
) variant. As amylolitic activity should not 
be too high or too low the impact on quality would depend upon characteristic of 
particular genotype. In treated (T
1
) variant, genotype with too low amylolitic activity 
would have improved this quality parameter, and opposite. 
 
Finally, test baking gives the best illustration of flour quality. While treated variants 
(T
1
) had on average slightly higher dough yield (results of higher water absorption 
due to higher protein content) in the bread yield there were no differences between 
variants and in the volume yield on average untreated (T
0
) variant was superior. 
(Tab.3; Fig.4) 
 
 

Acta agriculturae Slovenica, 87 - 2, september 2006 
 
386 
 
 

SAMOBOR, V. et al: Effect of powdery mildew attack on quality parameters … 
 
 
 
387
 
 
 
 
 
 
 
 

Acta agriculturae Slovenica, 87 - 2, september 2006 
 
388 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fig.4. Bread loaf cross-section of treated (T
1
) and untreated (T
0
) variant  of cv. 
Divana and cv. Široka, grown in 2001. 
 

SAMOBOR, V. et al: Effect of powdery mildew attack on quality parameters … 
 
 
 
389
Table 3. Difference between T
0  
and T
1  
in  rheologycal and test bread baking 
parameters for seven cultivars/lines tested at Križevci, Croatia, in two years 
(2000 and 2001) 
 
No. Parameter Treatment * 2000 2001 Average 
readings 
Difference 
1         Farinograph  
T
1
         64.3  62.6  63.5 
 1.1 Water absorption (%)
T
0 
64.3 61.2  62.8 
>      0.7 
T
1 
3.36  2.36      2.88 
1.2 Dough development (min)
T
0 
4.20   2.64     3.42 
>     -0.54 
T
1 
0.50  0.64     0.57 
1.3 Stability (min)
T
0 
 1.10  1.57     1.34 
>     -0.77 
T
1 
 3.86  3.00     3.43 
1.4 Resistance (min)
T
0 
 5.29  4.10     4.70 
>      -1.27 
T
1 
 91  99    94.3 
1.5 Degree of softening (FU)
T
0 
 76  69    72.9 
>      21.4 
T
1 
58.1 55.1    56.6 
1.6 Quality number
T
0 
62.0 62.5    62.3 
>      -5.7 
2         Extensograph  (135 mn) 
T
1 
 70.39 76.17     73.28 
2.1 A   Energy   (sqcm)
T
0 
 59.97  91.00    75.49 
>     -2.21 
T
1 
 165.71 158.29 162.00 
2.2 B   Extensibility   (min)
T
0 
 157.14 163.14 160.14 
>       1.86 
T
1 
 237.14 261.43 249.29 
2.3   C   Resistance  (EU)
T
0 
 209.29 295.00 252.15 
>      -2.86 
T
1 
 325.71 367.86 346.79 
2.4 D   Max. resistance   (EU)
T
0 
 277.14 427.86 352.50 
>      -5.71 
T
1 
 1.47  1.71       1.59 
2.5 Proportion C/B    (EU/min)
T
0 
 1.34  1.84       1.59 
>        0.0 
3          α-amylase activity 
T
1 
329 262 296 
3.1 Falling number (Hagberg-Perten)
T
0 
337 299 318 
>       22 
4         Bread parameters  
T
1 
164.8  166.8   165.8 
4.1 A)  Dough yield (g)  at 14% v.b.
T
0 
 164.7 158.5  161.6 
>       4.2 
T
1 
 155.4  157.3  156.4 
4.2 B)  Bread yield (g)  at 14% v.b.
T
0 
 155.5 156.6  156.1 
>       0.3 
T
1 
 416.2 430.5  423.4 
4.3 C)  Volume yield (cm
3
) at 14% v.b. 
T
0 
 431.5 426.8  429.2 
>      -5.8 
T
1 
     0.89     0.93      0.91 
4.4 D)  Bread shape: h/d 
T
0 
    0.94      0.89      0.92 
>       0.0 
*T
1
 = with fungicide Duett treated, and T
0
 = untreated variant 
 
There have been numerous reports about negative effects of powdery mildew attack 
on grain protein content and test weight of wheat. Our results also verify earlier 
discoveries. We were also expecting similar impact of powdery mildew on other 
quality parameters of wheat but to our surprise our investigations generally detected 

Acta agriculturae Slovenica, 87 - 2, september 2006 
 
390 
better quality parameters in untreated (T
0
) variants. Since very divergent genotypes 
were included in investigation, from resistant to very susceptible wheat, and also from 
excellent to poor quality genotypes, the results generally could be taken as 
representative for wheat. As, in both years, completely resistant wheat line 
KS92WGRC21 had better quality parameters in untreated variant, the speculation 
could be made about negative side effect of the used fungicide (Duett) on quality 
parameters. Even the untreated variants of genotypes susceptible to powdery mildew 
had better quality performances and that corroborated our speculations. However, due 
to very complex polygenic mechanism of resistance as well as some complex and 
polygenic mechanism of bread quality these speculations should be additionally 
checked and revised.  
 
 
4      CONCLUSIONS 
 
The more or less infected wheat (T
0 
variant) that was untreated with fungicide Duett 
displayed generally better bread baking quality parameters (except test weight, grain 
protein content and dough yield) in comparison with treated (T
1
) variant. There are 
certain speculations about the possible negative side effect of applied fungicide Duett 
based on obtained readings. For validity these speculations should be additionally 
checked. 
 
 
5       ACKNOWLEDGEMENTS 
 
The reported investigations were a part of the scientific project “Breeding high quality 
wheat for sustainable agriculture” (4-01-176) with the financial help from the 
Croatian Ministry of Science and Technology in the period 1998-2001. Rheological 
analyses and experimental test bakings were conducted at The Faculty of Food 
Technology and Biotechnology, Zagreb University. Many valuable advices were 
received from Dorian Weipert, Detmold, Germany. We express gratitude for their 
support. 
 
6     REFERENCES 
 
Bowen, K.L., Everts, K.L. and Leath, S. 1991. Reduction in yield of winter wheat in North 
Carolina due to powdery mildew and leaf rust. Phytopathology, 81:503-511.  
Carver, T.L.V. and Griffiths, E. 1981. Relationship between powdery mildew infection, green 
leaf ares and grain yield of barley. Annals of Applied Biology, 99:255-266.  
Cvjetković, B. 2003. Pepelnica pšenice. Glasilo biljne zaštite. III (5):288-291. 
Everts, K.L., Leath, S. and Finney, P.L.. 2001. Impact of Powdery Mildew and Leaf Rust on 
Milling and Baking Quality of Soft Red Winter Wheat. Plant Disease, 85(4):423-
429. 
Fehr, W.R. 1987. Principles of cultivar development – Theory and technique. Macmillian 
Publishing Co. New York, 1:536. 

SAMOBOR, V. et al: Effect of powdery mildew attack on quality parameters … 
 
 
 
391
Fried, P.M., MacKenzie, D.R. and Nelson, R.R. 1976. Critical point model to estimate yield 
loss caused by powdery mildew on Chancellor wheat. Proc. Am. Phytopatol. Soc. 
3:304-305.  
Gair, R., Jenkins, J.E.E. and Lester, E. 1983. Cereal pests and diseases. (Third edition), 
Farming Press Ltd. p. 259. 
Gooding, M.J., Smith, S.P., Davies, W.P. and Kettlewell, P.S. 1994. Effects of late-season 
applications of propioconazole and tridemorph on disease, senescence, grain 
development and the bread-making quality of winter wheat. Crop Protection, 
13:362-370. 
Henry, R.J. and Kettlewell P.S. 1996. Cereal grain quality. Chapman & Hall, London, p.488. 
Johnson, J.W., Baenziger, P.S., Yamazaki, W.T. and Smith, R.T. 1979. Effects of powdery 
mildew on yield and quality of isogenic lines of ‘Chancellor’ wheat. Crop Sci. 
19(3):349-352. 
Kišpatić, J. 1984. Sadašnje stanje suzbijanja pepelnice strnih žita. Glasnik zaštite bilja. VII 
(5):163-165. 
Korić, B. 1991. Zastupljenost patotipova Erysiphe graminis f.sp. tritici u zapadnom dijelu 
Jugoslavije od 1968. do 1990. godine. Agronomski glasnik, 4-5:241-253. 
Korić, B. 1994. Occurence and frequency of the patotypes of Blumeria graminis 
D.C.f.sp.tritici March in Croatia from 1988 to 1992. Fragmenta phytomedica et 
herbologica, 22(1-2):5-12. 
Large, E.C. 1954. Growth stages in cereals: illustration of the Feekes scale. Plant Pathol., 
3:128-129. 
Large, E.C. and Doling, D.A. 1962. The measurement of cereal mildew and its effect on yield. 
Plant Pathology. 11:47-54.  
Large, E.C. and Doling, D.A. 1963. Effect of mildew on yield of winter wheat, Plant 
Pathology, 12:128-130. 
Samobor, V. and Jošt, M. 1999. Search for gene donors of resistance to powdery mildew (E. 
graminis D.C. f.sp. tritici Marchal) in winter wheat genotypes (T. aestivum ssp. 
vulgare). Agriculture, 5(2):23-29. 
Samobor, V., Vukobratović, M. and Jošt, M. 2005. Effect of powdery mildew (Erysiphe 
graminis D.C. f.sp. tritici Marchal) attack on yield and physical parameters of wheat 
(Triticum aestivum ssp. vulgare) grain quality. Agriculture, 11(2):30-37.  
Saari, E.E. and Prescott J.M. 1975. A scale for appraising for fliiar intensity of wheat 
diseases. Plant Diseases Reporter, 59:377-380.  
Špehar, V. 1968. Utvrđivanje proširenosti i dominantnosti fizioloških rasa pepelnice 
(Erysiphe graminis f.sp. tritici) u Hrvatskoj. Izvještaj o znanstvenom radu za god. 
1967, p. 1-5.  
Xiu-Quiang, H. and Röder, M.S. 2004. Molecular mapping of powdery mildew resistance 
genes in wheat: A review. Euphytica, 137(2):203-223.