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La Podredumbre de raíces y corona (PRC) del espárrago (Asparagus officinalis L.), de etiologíacompleja, incluyendo varias especies de Fusarium, y la Fusariosis vascular (FV) del tomate (Solanumlycopersicum L.) ocasionada por Fusarium oxysporum f. sp. lycopersici (Fol), están presentes en lamayoría de las zonas de cultivo del mundo y causan graves pérdidas económicas. Su control es difícildebido a la prolongada supervivencia de los patógenos en el suelo y su fácil diseminación con elmaterial de propagación. Además, los cultivares de espárrago suelen tener escasa resistencia, que esdifícil de implementar por la amplia diversidad genética dentro de las especies de Fusariumpatogénicas de espárrago y, aunque los cultivares de tomate resistentes a la Fusariosis han estadodisponibles desde hace décadas y proporcionan un cierto grado de control, la aparición y desarrollo denuevas razas patogénicas supone un problema constante. De hecho, no existen variedades de tomatecomercialmente aceptables con una resistencia suficiente. Para el manejo de estas enfermedades haypocas opciones de control químico disponibles. Una alternativa sostenible y ecológica es el uso deenmiendas orgánicas de suelo, que pueden reducir el impacto de hongos de suelo fitopatógenos(Lazarovits, 2001; Noble y Coventry, 2005; Bonanomi et al., 2007; Melero-Vara et al., 2011). Estetrabajo se ha realizado en el marco de una agricultura ecológica, utilizándose residuos orgánicos de laindustria agrícola y pesquera de la zona (gallinaza, pellet comercial de gallinaza, compost de alpeorujoy emulsión de pescado) como enmiendas orgánicas de suelo en ambos patosistemas Fusariumspp./espárrago y Fusarium oxysporum f. sp. lycopersici / tomate.El primer objetivo de la presente Tesis Doctoral fue evaluar la eficacia de la temperatura yperiodo de incubación del sustrato en combinación con las enmiendas orgánicas gallinaza, pellet degallinaza y compost de alpeorujo, en el control de la PRC del espárrago causada, en España, porFusarium oxysporum (Fo), F. proliferatum (Fp) y F. solani (Fs). Para ello se determinó la viabilidad delos propágulos de los aislados de Fusarium spp. en un sustrato artificialmente infestado y enmendadoque se incubó a 30 ó 35ºC durante diferentes periodos (15, 30 y 45 días). Por lo general, la viabilidadde los inóculos estuvo considerablemente afectada por la temperatura y el periodo de incubación,produciéndose una mayor reducción de aquélla cuando se combinó con la aplicación de enmiendasorgánicas. La mayor reducción de la viabilidad se produjo con los periodos de incubación más largos(45 días) y a 35ºC se alcanzaron mayores pérdidas de viabilidad que a 30ºC, siendo el pellet degallinaza la enmienda orgánica más efectiva en reducir la viabilidad de Fo y Fs. Sin embargo, laviabilidad de los propágulos de Fp fue generalmente similar a las del testigo infestado sin aporte deenmienda, sobre todo cuando la incubación fue a 30ºC. Tras la incubación, fueron trasplantadasplántulas de espárrago del cv. Grande a macetas con los sustratos infestados por las distintas especiesde Fusarium, y a los tres meses se determinó la severidad de las lesiones en el sistema radical y elpeso fresco de las plantas. Los resultados mostraron disminuciones muy significativas de la severidadde síntomas radicales. El inóculo de Fp causó una menor severidad de síntomas de raíz que losaislados Fo y Fs. En el tratamiento con pellet de gallinaza, la disminución de la severidad de síntomasfue mayor, especialmente a 30ºC (a los 30 y 45 días en el caso de Fo, y a los 15 días en el caso deFs), así como con gallinaza al 2% (con Fo y Fs a las dos temperaturas de incubación y, generalmente,durante periodos de 30 y 45 días), y con compost de alpeorujo (por lo general con 15-30 días deincubación). Los incrementos del peso fresco de las plantas de espárrago fueron, generalmente,..., Fusarium crown and root rot (FCRR) of asparagus (Asparagus officinalis L.), with a complexetiology including several Fusarium spp., and Fusarium wilt (FW) of tomato (Solanum lycopersicum L.),caused by Fusarium oxysporum f. sp. lycopersici (Fol), occur in most growing areas of the world andcan cause serious economic losses. Its control is difficult due to the long survival of pathogens in thesoil and their easy spreading by propagation material. In addition, asparagus cultivars available oftenhave low resistance levels and, due to the wide genetic diversity within species of Fusarium pathogenicof asparagus, implementation of resistance is difficult to develop. On the other hand, tomato cultivarsresistant to Fusarium have been available for decades and provide a certain degree of control, but theemergence and development of new pathogenic races is a constant problem. In fact, commerciallyacceptable varieties of tomato with complete resistance are not frequent. Therefore, there are fewchemical control options available for the management of these diseases. A sustainable andenvironmentally friendly alternative is the use of organic soil amendments that can greatly reduce theimpact of soilborne plant pathogens (Lazarovits, 2001; Noble y Coventry, 2005; Bonanomi et al., 2007;Melero-Vara et al., 2011). This work has been conducted in the framework of organic farming sinceorganic by-products from agricultural and fishing industries in the area (poultry manure, commercialpellet of poultry manure, olive residue compost and fish emulsion) have been tested as organic soilamendments aiming disease control for the pathosystems Fusarium spp./asparagus and Fusariumoxysporum f. sp. lycopersici / tomato.The first objective of this Thesis was to evaluate the effectiveness of temperature and incubationperiod in combination with several organic amendments (poultry manure, commercial pellet of poultrymanure, olive residue compost) in substrate mixture, on the management of FCRR of asparaguscaused by Fusarium oxysporum (Fo), F. proliferatum (Fp) and F. solani (Fs), the most important inSpain. The propagule viability of Fusarium spp. isolates was determined on a substrate artificiallyinfested and amended which was incubated at 30 or 35ºC for periods of 15, 30 and 45 days. Overall,the viability of the inocula was significantly affected by temperature and incubation period, resulting in afurther reduction of the former when combined with the application of organic amendments. Thegreatest reduction in pathogens viability occurred with the largest incubation period (45 days) and largerloss of viability was achieved at 35ºC than at 30ºC, with pellet of poultry manure as the most effectiveorganic amendment in reducing the viability of Fo and Fs. However, the viability of propagules of Fp wasusually similar to that in infested and un-amended control, especially when incubation was at 30ºC. Afterincubation, seedlings of asparagus cv. Grande were transplanted into pots containing substratesinfested by the different species of Fusarium. After three months, the severity of symptoms in the rootsystem and fresh weight of the plants were assessed. Results showed highly significant decreases inthe root symptom severity. Fp inoculum caused a lower severity than Fo and Fs isolates. After substratetreatment with pellet of poultry manure, reduction of symptoms severity was higher particularly at 30ºC(by 30 and 45 days incubation of Fo-infested substrate, and by 15 days incubation of Fs-infestedsubstrate). Similarly, reductions in severity were observed with the higher poultry manure doses (in Foand Fs-infested substrate incubated at both temperatures and, usually, for 30 and 45 days), and oliveresidue compost (usually by 15-30 days incubation). Fresh weight increase of asparagus plants wereoverall, significantly high in Fo and Fs substrate infestations with any of the three organic amendmentstested.

Organic soil amendments play important roles in the reduction of plant diseases caused by soil-borne plant pathogens. This study examined the combined effects of concentrations of organic amendments, temperature and period of incubation in soil on the management of Fusarium wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici (Fol). In an experiment with substrate mixture, Fol reduction was higher when the soils were incubated at 35°C than at 30°C. Disease severity was proportionally reduced as the volume of amendment added increased. Furthermore, disease was significantly lower in substrates incubated for 30-days at both temperatures, as compared to substrates incubated for only 15-days. The most effective control was achieved with pelletised poultry manure (PPM). In experiments with natural sandy soil, the effects of amendments on Fol populations, measured by real-time quantitative PCR with TaqMan probes, were significant. The highest decreases in Fol DNA resulted when the soil was amended with 2% PPM and incubated at 35°C. The reductions in DNA concentrations was most likely related to the accumulations of high concentrations of NH3 (27.3-mM) in soils treated with 2% PPM and incubated at room temperature (RT; 23-±-2°C), or at 35°C. Severity of plants grown in soils incubated at RT decreased by over 40%, and more than 73% when incubated at 35°C, regardless of the rate of PPM. The results indicate that the management with PPM, when combined with heating or solarisation, is an effective control measure against Fusarium wilt of tomato. © 2014 Association of Applied Biologists., This study was funded by Agri-Food Canada Matching Investment Initiative, by a JAEPredoc-CSIC grant to A. Borrego-Benjumea and by projects INIA RTA 2006-00045 (Ministerio de Agricultura, Alimentación y Medio Ambiente, Spain) and P06-AGR-02313 (Consejería de Economía, Innovación y Ciencia, Junta de Andalucía).

Efficacy of organic amendments and incubation temperature on the control of Fusarium spp. from asparagus