Journal of Plant Pathology - Sipav.org

Journal of Plant Pathology (2011), 93 (1, Supplement), S1.19-S1.26 S1.23
In the endosphere, the arbuscular mycorrhizal fungi (AMF) may
play an important role in host plant disease resistance. The objective
of the present study was to test if inoculation of maize plants
with the arbuscular mycorrhizal fungus, Glomus intraradices, alters
the interaction among plants, indigenous microbial communities
in the rhizo- and endosphere of maize, and WCR root feeding
and development. The experiment was carried out in a greenhouse,
in pots containing Chernozem soil. The maize cultivar used
was the commercial line KWS13. Four different treatments were
established: (i) control maize plants grown for eight weeks; (ii)
maize plants grown in soil inoculated with G. intraradices before
sowing; (iii) maize plants subjected, after the 4th week of growing,
to WCR larval feeding; (iv) maize plants grown in soil inoculated
with G. intraradices before sowing and subjected after the 4th
week of growing, to WCR larval feeding. Eight weeks after sowing,
the plants were harvested in order to (i) evaluate the larval
feeding effect on the dry biomass of the roots; (ii) investigate the
AMF communities in the maize roots by PCR-RFLP; (iii) analyse
the fungal and bacterial composition in the rhizosphere and in the
endosphere of maize by DGGE (denaturing gradient gel electrophoresis).
In parallel, the larvae, which had fed for four weeks
on the roots were extracted from soil of treatments III and IV, to
evaluate the larval stage and the developmental level of the 3 rd instar
larvae. Plant root biomass measurements showed that G. intraradices
did not affect significantly larval feeding of the roots.
Analysis of the total number of larvae and of the composition of
larval instars revealed that G. intraradices did not influence the total
number of WCR larvae but reduced significantly their development
for the weight of the 3 rd larval stage was significantly lower
in Glomus-treated plants in comparison with the controls
(P=0.02). RFLP analysis of AMF populations showed that the soil
inoculation with G. intraradices reduced the AMF evenness in
maize roots almost exclusively to the RFLP type 11 (G. intraradices).
ITS- and 16S-DGGE analysis showed a specific shift
in both bacterial and fungal composition in the roots of plant colonized
with G. intraradices. The additional dominant bands in the
ITS-DGGE profile were identified by sequencing as G. intraradices.
In conclusion, this work showed that G. intraradices
significantly reduced larval development. Furthermore, the shift
of bacterial communities in the endosphere of G. intraradices-inoculated
plants, suggests that other microorganisms may be involved
in decreasing the developmental level of larvae. However,
the colonization of maize plants with G. intraradices should be
further studied as an option to control WCR larvae in the framework
of integrated pest management strategies.
HEALTH PROTECTION OF STRAWBERRY IN MON-
TENEGRO. N. Latinovic 1 , J. Latinovic 1 , S. Hrncic 1 and D.
Sukovic 2 . 1 University of Montenegro, Biotechnical Faculty, Mihaila
Lalica 1, 20 000 Podgorica, Montenegro. 2 PI Centre for Ecotoxicological
Research of Montenegro, 20 000 Podgorica, Montenegro.
E-mail: nlatin@ac.me
During the last three years, strawberry became an important
crop in Montenegrin agriculture with more than 1,500,000 plants
planted. During 2010, four strawberry fields were monitored,
taking into account problems caused by harmful organisms that
jeopardize crop health. The most important diseases were strawberry
leaf spot (Mycosphaerella fragariae (Tul.) Lindau) and grey
mold (Botrytis cinerea Pers.), while the presence of aphids was
detected in only one location. Weeds did not cause significant
problems because of plastic mulching along the rows, which
made mechanical weeding necessary only between rows. Fungicides
for strawberry leaf spot control were azoxystrobin
(Quadris), difenilconazole (Score 250) and copper-based products
whereas for grey mould they were fenhexamid (Teldor 500),
vinclozolin (Ronilan) and cyprodinyl+fludioxonil (Switch). Strawberry
fruits were analised for the presence of pesticide residues by
GC-MS and/or LC-MS/MS following acetonitrole extraction/partitioning
and clean-up by dispersive SPE-Quechers-method, DIN
EN 15662:2009-02. Results showed that there were no detectable
pesticide residues or they were below the maximum residue level
(EU-MRLS; Regulation No. 369/2005), indicating that strawberries
grown in the surveyed localites of Montenegro were safe for
human consumption with respect to fungicides.
SENSITIVITY OF SIMULATED SURFACE WETNESS DU-
RATION TO METEOROLOGICAL VARIATIONS IN
THREE DIFFERENT REGIONS OF THE GRAND-DUCHY
OF LUXEMBOURG. A. Mahtour 1 , M. El Jarroudi 1 , L. Hoffmann
2 and B. Tychon 1 . 1 University of Liège, 185 Avenue de Longwy,
6700 Arlon, Belgique. 2 Centre de Recherche Public-Gabriel
Lippmann, Département Environnement et Agro-biotechnologies,
41 Rue du Brill, 4422 Belvaux, Luxembourg. E-mail: meljarroudi
@ulg.ac.be
Leaf surface wetness duration (SWD) is an important factor
influencing the occurrence of winter wheat diseases. Thus, SWD
is extremely important for the management of crop protection activities.
In order to understand the SWD variability and its influence
on winter wheat diseases, the objective of this study was to
(i) determine the sensitivity of our model on varying input plant
parameters and (ii) evaluate the influence of simulated SWD on
meteorological variations in three different climatic regions
(Everlange, Obercorn, Schimpach) of the Grand-Duchy of Luxembourg.
Hourly weather data for the three sites were obtained
from the ASTA (Administration des Services Techniques de l’Agriculture)
automatic weather station network. The simulation of
surface wetness duration was made with the Surface Wetness Energy
Balance (SWEB) simulation model. The agrometeorological
inputs of the model are air temperature (°C), relative humidity
(%), precipitation (mm), wind speed (m/s) and radiation above
the canopy (W/m 2 ); the output is represented by the fraction (%)
of the leaf surface covered by water (the percentage of wet leaf
surface, W). The W parameter is a continuous variable and, was
used for comparing estimates of the wet area of a canopy at any
given time. The estimated number of wet hours per day (N n
),
changes in net radiation, wind speed, temperature, rainfall rate
and relative humidity were also taken into account. Each of these
measured variables was increased and decreased by 10% (where
RH was truncated at 100% if necessary). The model was rerun
and the difference in wet hours predicted by the default model
(the model without any change in any of the variables), N ndef
, and
the adjusted model (the model after one variable or parameter
had been changed), N nnew
, was calculated. The absolute values of
these differences were averaged over monthly periods, and referred
to as the sensitivity S +
and S -
, for positive and negative
changes, respectively, to the variables:
Since S +
and S -
were very similar, only mean values are given
here. In this work, an agrometeorological model known as the
Surface Wetness Energy Balance (SWEB) was applied for the
simulation of SWD. The model was previously applied in another
study for winter wheat cultivars and was adapted for use with
agrometeorological data available from standard meteorological
monitoring stations. Based on weather data and simulated SWD
data, sensitivity analyses were performed to compare the effects
of relative humidity, air temperature, wind speed and net radia-