MANEJO INTEGRADO DE ENFERMEDADES EN CEBADA (Hordeum vulgare L.) Y EVALUACIÓN DE FUNGICIDAS PARA EL CONTROL DE Ramularia collo-cygni - INTEGRATED DISEASE MANAGEMENT IN BARLEY (Hordeum vulgare L.) AND EVALUATION OF FUNGICIDES FOR THE CONTROL OF Ramularia collo-cygni

Abstract

The current management of diseases in barley in Argentina lies on the use on seed coated and foliar fungicides. In addition to causing a high impact on the environment, it generates selection pressure on pathogens causing resistance to fungicides. Integrated disease management (IDM) proposes strategies that include field rotation, host genetic resistance, chemical control among others. Barley varieties in Argentina are susceptible to Ramularia Leaf Spot (RLS, Ramularia collo-cygni). This is a pathogen with high risk of generating resistance to fungicides and it is only controlled with very few active ingredients. The objective was to evaluate the control efficiency (CE) of fungicides registered for RLS in a context of IDM strategies for the other diseases. A field trial was performed in microplots with four replicates (DBCA) in the EEA Balcarce with various IDM strategies: 1- Andreia variety, intermediate resistance to net bltoch (Drechslera teres), 2- Late sowing (22/07) avoiding low temperatures that favor the development of scald (Rhynchosporium commune ), 3- Helath seed analysis: the presence of pathogens (blotter test) was determined, 4- Field selection: no history of barley avoiding source of inoculum (barley debris), 5- Chemical control for the RLS: six fungicide treatments reported for this disease with carboxamides and / or prothioconazole and a multisite, applied in flag leaf and a control without fungicides (SF). No presence of D. teres was observed in the seed samples analyzed, so no seed coated fungicide was used. No diseases present except for SN were observed. The CE of the RLS was high for all proposed fungcides treatments that varied between 70 and 100% where it was achieved on average 1000 kg/ha more than the control (3700 kg/ha) (p< 0.05). - El manejo actual de enfermedades en cebada en Argentina radica especialmente en el uso de fungicidas en semilla y foliares. Además de provocar un alto impacto al medio ambiente, genera presión de selección sobre los patógenos provocando resistencia a los fungicidas. El manejo integrado de enfermedades (MIE) propone estrategias que incluyen rotación de lote resistencia genética, control químico entre otras. Las variedades de cebada en Argentina son susceptibles al salpicado necrótico (SN, Ramularia collo-cygni). Este hongo patógeno de alto riesgo de generación de resistencia a fungicidas es controlado con muy pocos ingredientes activos. El objetivo fue evaluar la eficiencia de control (EC) de fungicidas registrados para el SN en un contexto de MIE de las demás enfermedades. Se implantó un ensayo en microparcelas con cuatro repeticiones (DBCA) en la EEA Balcarce con diversas estrategias MIE: 1- Variedad Andreia, comportamiento intermedio a mancha en red (Drechslera teres), 2- Siembra tardía (22/07) evitando temperaturas bajas que favorecen el desarrollo de escaldadura (Rhynchosporium commune), 3- Análisis sanitario de semilla: se determinó presencia de patógenos (blotter test), 4- Selección de lote: sin historia de cebada evitando fuente de inóculo (rastrojo), 5- Control químico para el SN: seis tratamientos de fungicidas reportados para esta enfermedad con carboxamidas y/o protioconazol y un multisitio, aplicados en hoja bandera y un testigo sin fungicidas (SF). No se observó presencia de D. teres en las muestras de semillas analizadas por lo que no se utilizó curasemilla. No se observaron enfermedades presentes a excepción del SN. La EC del SN fue alta para todos los tratamientos de control químico planteados que varió entre 70 y 100% donde se logró en promedio 1000 kg/ha más que el testigo (3700 kg/ha) (p< 0.05).

Full text

Integrated disease management in barley (Hordeum vulgare L.) and evaluation
of fungicides for the control of Ramularia collo-cygni
1INTA Manfredi, 2 Fitopatología, FAUBA. erreguerena.ignacio@inta.gob.ar
It is possible to implement MIE
strategies to reduce the occurrence
of diseases thus reducing the
number of fungicide applications
per season in barley crop. It will be
important to continue and expand
this type of studies to provide
information for sustainable
production.
Conclusions
Materials and Methods
Introduction
Integrated disease management (IDM) proposes
strategies such as cultural measures, genetic resistance
and chemical control among others. Barley varieties in
Argentina are all susceptible to Ramularia Leaf Spot
(RLS, Ramularia collo-cygni).
Results
-No presence of D. teres f sp
teres in the seeds analysed was
observed.
-RLS was the only disease
observed.
-The CE of the proposed
treatments was high and varied
between 70-100% achieving 1 t/
ha (average) more than the SF
control (3700 kg/ha, P<0.05)
(Figure 1).
-
Erreguerena IA1., Carmona MA2.
The objective was to evaluate the control efficiency
(CE) of fungicides registered for RLS in a context of
IDM of other diseases affecting the crop.
Trial in microplots (10 m2) with four replicates (DBCA) in
the EEA Balcarce with several IDM strategies:
1- Andreia variety, intermediate behavior to net spot
blotch (Drechslera teres f sp teres)  Resistance.
2- Late sowing date (22/07) avoiding low temperatures
that favor scald (Rhynchosporium commune) 
Evasion/Regulation.
3- Seed health - Blotter test x freezing  Exclusion.
4- Field without inoculum source (debris)  Evasion.
5- Chemical control of RLS: six treatments with
fungicides applied in flag leaf stage and control without
fungicide (SF) (Table 1)  Protection/Therapy.
Treatments Active ingredients Dose (cc/ha)
1 prothioconazole + trifloxistrobin 700
Adyuvant 250
2prothioconazol + trifloxistrobin +
bixafen 700
Adyuvant 250
3fluxapyroxad + epoxyconazol +
piraclostrobin 1200
4 isopyrazam + azoxistrobin 500
5clorotalonil + (prothioconazol +
trifloxistrobin) 1500 + 700
6chlorothalonil + (fluxapyroxad +
epoxiconazole + piraclostrobin) 1500 + 1200
7 no fungicide 0
Figura 1. RLS control efficiency (Abbot,1925) and yield).
Table 1. Description of chemical
protection treatments
0
1000
2000
3000
4000
5000
6000
0
20
40
60
80
100
120 Yield Control Eff iciency
Yield (t /ha )
Contr ol effic ien cy (%)
R2=0.93, CV=41.4
R2=0.51, CV=19