Late blight on potato in Flanders, Belgium: field trials and characteristics of the Phytophthora infestans population

Commercial fungicides were tested in the field for efficacy on foliar late blight caused by Phytophthora infestans. The fungicide treatments for late blight control were conducted at either 7- or 10-day intervals. The effect of the fungicide treatments on epidemic development, tuber rot and blight incidence and tuber yields were determined. Last summer late blight development was arrested in July and at the beginning of August due to high temperatures and lasting drought. Foliar disease severity significantly affected potato tuber yields. Lowest tuber yield was noted in plots with high late blight infection levels (nontreated control and an experimental mixture of organic acids (Vi-Care, 1 l/ha)) while highest yields were recorded in plots with low late blight infection. Late blight infection on leaf level was not significantly correlated with % tubers that showed late blight symptoms. No fungicide scheme completely arrested epidemic development under the environmental conditions of the trial. The effect of propamocarb hydrochloride + chlorothalonil (Tattoo C, 2.5 kg/ha) was less suppressive for P. infestans than the other fungicides tested for both interval systems. However, fenamidone + mancozeb (Sereno, 1.5 kg/ha), zoxamide + mancozeb (Unikat Pro, 1.8 kg/ha), dimethomorph + mancozeb (Acrobat, 2 kg/ha), cyazofamide + heptamethyltrisiloxane (Ranman 200 ml A/ha + 150 ml B/ha) and cymoxanil + famoxadone (Tanos, 0.6 kg/ha) controlled P. infestans most effectively for both interval systems. Also the other fungicides controlled foliar late blight sufficiently. Only small differences were observed between the different treatments. A total of 51 isolates of P. infestans were collected from disease outbreaks in commercial potato crops and private gardens in 2003. Isolates were recovered successfully from single lesions of diseased potato foliage. Not from all isolates pure cultures were obtained due to contaminations with Fusarium species and bacteria. The structure of the population was analysed phenotypically. Characteristics of the isolates included in vitro growth rate, mating type, in vitro sensitivity to the phenylamide fungicide metalaxyl-M and allozyme genotype at glucose-6-phosphate isomerase (Gpi) and peptidase (Pep) loci

Evaluación de la efectividad de distintos ingredientes activos en el control preventivo de alternaría (Alternaria alternata) en un huerto de tomate industrial de la región del Maule

37 p.El tomate industrial es uno de los cultivos hortícolas más importantes a nivel nacional, siendo ampliamente afectado por diversas enfermedades, destacando las de origen fúngico. El estudio de éstas resulta relevante pues provocan daños a nivel del fruto generando importantes pérdidas económicas al productor. Alternaria alternata constituye una de las enfermedades más importantes pues se encuentra presente en gran parte de nuestro país. Para el control de esta enfermedad resulta fundamental el control químico, ya sea curativo o preventivo.En el presente ensayo se evaluaron, a nivel de campo, diferentes ingredientes activos y mezclas con distintos modos de acción con el objetivo de determinar la mejor opción presente en el mercado para el control de este patógeno. El ensayo se realizó en un huerto de tomate industrial y se consideró un diseño de bloques completamente al azar (DBA) con 10 tratamientos y cuatro repeticiones, incluyendo al testigo. Se realizaron cuatro aplicaciones iniciando en post cuaja y cuatro mediciones. La primera medición se realizó al inicio del ensayo y tres mediciones consecutivas cada siete días, iniciando desde la última aplicación de fungicidas. Se evaluó incidencia en plantas y severidad en frutos.Los resultados indican que los ingredientes activos azoxystrobin, azoxystrobin + zoxamida presentaron mejor control en la incidencia de la enfermedad en plantas. Mientras que en control de la severidad, los ingredientes azoxystrobin, azoxystrobin + zoxamida, difenoconazole y mancozeb sobresalieron estadísticamente del resto en el control de los frutos. Palabras claves: Alternaria alternata, azoxystrobin, azoxystrobin + zoxamida, difenoconazole y mancozeb./ABSTRACT: Industrial tomato is one of the most important horticultural crops nationwide, which is widely affected by various diseases, especially the ones who have a fungal origin. Studying them becomes relevant because they cause damages to the fruit, which generates significant economic losses. Particularly, Alternaria alternata is one of the most critical diseases because it is found in different regions of Chile. For controlling this specific disease, the chemical control becomes a fundamental part, whether it is curative or preventive. In this trial, various active ingredients and mixtures were evaluated at field level with different modes of action, in order to determine which one is the best option current available on the market for controlling this pathogen.The trial was conducted in an industrial tomato orchard and a design randomized block (DBA) was implemented, with ten treatments and four repetitions. First of all, four applications were done, beginning in post setting fruit, and also four measuring were made. The first measuring was performed at the beginning of the trial and then three consecutive measuring every seven days were made, starting since the last fungicide application. Besides, incidence and severity in fruit plants were evaluated and controlled.The results indicate that the active ingredients azoxystrobin, zoxamide + azoxystrobin showed better control in the incidence of the disease in the plants. On the other hand, in controlling severity, the ingredients azoxystrobin, azoxystrobin + zoxamide, difenoconazole and mancozeb, statistically excelled among the others in controlling the fruit.Key words:: Alternaria alternata, azoxystrobin, azoxystrobin + zoxamida, difenoconazole y mancoze

Resistance Assessment for Oxathiapiprolin in Phytophthora capsici and the Detection of a Point Mutation (G769W) in PcORP1 that Confers Resistance

The potential for oxathiapiprolin resistance in Phytophthora capsici was evaluated. The baseline sensitivities of 175 isolates to oxathiapiprolin were initially determinated and found to conform to a unimodal curve with a mean EC50 value of 5.61×10-4 μg/ml. Twelve stable oxathiapiprolin-resistant mutants were generated by fungicide adaption in two sensitive isolates, LP3 and HNJZ10. The fitness of the LP3-mutants was found to be similar to or better than that of the parental isolate LP3, while the HNJZ10-mutants were found to have lost the capacity to produce zoospores. Taken together these results suggest that the risk of P. capsici developing resistance to oxathiapiprolin is moderate. Comparison of the PcORP1 genes in the LP3-mutants and wild-type parental isolate, which encode the target protein of oxathiapiprolin, revealed that a heterozygous mutation caused the amino acid substitution G769W. Transformation and expression of the mutated PcORP1-769W allele in the sensitive wild-type isolate BYA5 confirmed that the mutation in PcORP1 was responsible for the observed oxathiapiprolin resistance. Finally diagnostic tests including As-PCR and CAPs were developed to detect the oxathiapiprolin resistance resulting from the G769W point mutation in field populations of P. capsici

Evaluación de la efectividad de diferentes ingredientes activos en el control del agente causal de pudrición gris (Botrytis cinerea) en tomate industrial

32 p.Se realizo un estudio en plantas de tomate (Solanum lycopersicum) para evaluar la efectividad de diferentes ingredientes activos en el control del agente causal de pudrición gris (Botrytis cinerea). El ensayo fue llevado a cabo en el invernadero de la Facultad de Ciencias Agrarias de la Universidad de Talca (Región del Maule, Chile) durante la temporada 2012-2013. El diseño experimental fue completamente al azar, con 8 tratamientos con 4 repeticiones cada tratamiento y cada repetición con 4 plantas. Los ensayos no fueron inoculados directamente con el hongo Botrytis cinerea, sino que se estimularon las condiciones predisponente para que se estableciera de manera propia, así posteriormente observar el efecto de los fungicidas sobre las plantas enfermas, los cuales fueron aplicados en dos oportunidades en un periodo de 14 días. Los tratamientos evaluados corresponden a la aplicación de azoxystrobin (IMPULSO), difenoconazole (DOMINIO), pyrimetanil (BONNUS), azoxystrobin + pyrimetanil (IMPULSO + BONNUS), azoxystrobin + zoxamida (IMPULSO + ZOXAMIDA), azoxystrobin + difenoconazole (IMPULSO + DOMINIO), azoxystrobin + clorotalonilo (IMPULSO + HORTYL) y un tratamiento testigo sin presencia de fungicida. Las evaluaciones se realizaron 7 días posterior a la segunda aplicación de fungicida y se evaluó la incidencia en los tratamientos, en el cual azoxystrobin (T2) presento óptimo control, obteniendo diferencias significativas con el testigo. En cuanto a severidad azoxystrobin + difenoconazole (T7) y azoxystrobin + clorotalonilo (T8) presentaron diferencias significativas en relación al testigo con un control adecuado del hongo patógeno. Palabras claves: Solanum lycopersicum, fungicidas, Botrytis cinerea, incidencia y severidad/ABSTRACT:A study was carried out in tomato plants (Solanum lycopersicum) to evaluate the effectiveness of different active ingredients in controlling the causal agent of gray mold (Botrytis cinerea). The study was conducted in the greenhouse of the Faculty of Agricultural Sciences, University of Talca (Maule region, Chile) during the season 2012-2013. The experimental design was completely randomized, with 8 treatments, with 4 replicates each treatment and each replicate with 4 plants. The trials were not directly inoculated with the fungus Botrytis cinerea, but were stimulated predisposing conditions for the establishment of their own way, for then observe the effect of fungicides on diseased plants, which were applied twice in a period 14 days. The treatments correspond to the application of azoxystrobin (IMPULSO), difenoconazole (DOMINIO), pyrimethanil (BONNUS), azoxystrobin + pyrimethanil (IMPULSO + BONNUS), azoxystrobin + zoxamide (IMPULSO + ZOXAMIDA), azoxystrobin + difenoconazole (IMPULSO + DOMINIO) azoxystrobin + chlorothalonil (IMPULSO + HORTYL) and a control treatment without the presence of fungicide. Evaluations were made 7 days after the second application of fungicide and assessed the incidence in treatments, where azoxystrobin (T2) presented optimal control, obtaining significant differences with the control treatment. Regarding severity azoxystrobin + difenoconazole (T7) and azoxystrobin + chlorothalonil (T8) showed significant differences from control treatment with appropriate control of the pathogenic fungus. Keywords: Solanum lycopersicum, fungicides, Botrytis cinerea, incidence and severity

OSTANKI FITOFARMACEVTSKIH SREDSTEV V JABOLKIH, CVETAČI, ŽITIH, GROZDJU, SOLATI, GRAHU, PAPRIKI, KROMPIRJU IN JAGODAH SLOVENSKEGA POREKLA V LETU 2006

In the year 2006, 181 apple, cauliflower, cereal, grape, lettuce, pea, pepper, potato and strawberry samples from Slovene producers were analysed for plant protection product residues. The samples were analysed for the presence of 86 different active compounds using four analytical methods. In nine samples (5.0 %) exceeded maximum residue levels (MRLs) were determined which is comparable with the results of the monitoring of plant protection product residues in products of plant origin in the European union, Norway, Iceland and Liechtenstein in 2005 (4.9 %).V letu 2006 smo na ostanke pesticidov analizirali 181 vzorcev jabolk, cvetače, žit, grozdja, solate, graha, paprike, krompirja in jagod slovenskih tržnih pridelovalcev. Vse vzorce smo analizirali s štirimi analitskimi metodami na prisotnost 86 različnih aktivnih spojin. V devetih vzorcih (5,0 %) smo določili presežene maksimalno dovoljene količine ostankov, kar je primerljivo z rezultati monitoringa ostankov pesticidov v rastlinskih proizvodih v Evropski skupnosti, Norveški, Islandiji in Lihtenštajnu v letu 2005 (4,9 %)

Avaliação da potencial contaminação das águas superficiais e subterrâneas por agrotoxicos em áreas de produção de uva para exportação no Vale do São Francisco.

O sistema produtivo de uva irrigado do Vale do São Francisco é caracterizado pela ampla utilização de agroquímicos. Por meio da lixiviação e do escoamento superficial da água, os agrotóxicos podem ser transportados, prejudicando a qualidade das águas subterrâneas e superficiais. As propriedades físico-químicas dos agroquímicos bem como as características dos solos são determinantes para essa movimentação. Portanto, o conhecimento destes atributos, bem como adequação do manejo dos solos a estas propriedades, pode ajudar a minimizar o impacto ambiental. Em vista disso e para avaliar a qualidade dos corpos hídricos da região, foi realizado um estudo do potencial de contaminação dos agrotóxicos aplicados no cultivo de uva para exportação no Vale do São Francisco, empregando-se para estas análises os índices de GUS e GOSS. Como resultado, obteve-se uma lista discriminando quais apresentam maior risco de contaminação para os recursos naturais. No geral, constatou-se que os agrotóxicos utilizados oferecem baixo potencial de contaminação das águas subterrâneas e médio a alto potencial de contaminação das águas superficiais

Epidemiology and integrated control of Potato Late Blight in Europe

Phytophthora infestans, the causal agent of late blight, is a major threat to potato production in northwestern Europe. Before 1980, the worldwide population of P. infestans outside Mexico appeared to be asexual and to consist of a single clonal lineage of A1 mating type characterized by a single genotype. It is widely believed that new strains migrated into Europe in 1976 and that this led to subsequent population changes including the introduction of the A2 mating type. The population characteristics of recently collected isolates in NW Europe show a diverse population including both mating types, sexual reproduction and oospores, although differences are observed between regions. Although it is difficult to find direct evidence that new strains are more aggressive, there are several indications from experiments and field epidemics that the aggressiveness of P. infestans has increased in the past 20 years. The relative importance of the different primary inoculum sources and specific measures for reducing their role, such as covering dumps with plastic and preventing seed tubers from becoming infected, is described for the different regions. In NW Europe, varieties with greater resistance tend not to be grown on a large scale. From the grower’s perspective, the savings in fungicide input that can be achieved with these varieties are not compensated by the higher (perceived) risk of blight. Fungicides play a crucial role in the integrated control of late blight. The spray strategies in NW Europe and a table of the specific attributes of the most important fungicides in Europe are presented. The development and use of decision support systems (DSSs) in NW Europe are described. In The Netherlands, it is estimated that almost 40% of potato growers use recommendations based on commercially available DSS. In the Nordic countries, a new DSS concept with a fixed 7-day spray interval and a variable dose rate is being tested. In the UK, commercially available DSSs are used for c. 8% of the area. The validity of Smith Periods for the new population of P. infestans in the UK is currently being evaluated

Editable chemical structure files (SK2 and MDL mol) of pesticide active ingredients

This Dataset contains a long list of online, freely available sk2 and MDL mol files of a number of pesticide active ingredients for use by anyone interested (students, teachers, researchers, etc.)