A infecção de grãos de milho por Fusarium verticillioides, agente causal da podridão da espiga, pode resultar na produção de micotoxinas do grupo das fumonisinas. A resistência genética é a forma de controle mais eficiente dessa enfermidade. Assim, o objetivo do trabalho foi buscar fontes de resistência em linhagens de milho tropical à F. verticillioides e à produção de fumonisinas. Seis linhagens tropicais de milho, três, pré-classificadas como resistentes e três, pré-classificadas como suscetíveis à F. verticillioides, foram submetidas à inoculação do patógeno e posteriormente, avaliadas quanto à severidade da podridão de espiga, incidência de grãos sintomáticos e concentração de fumonisinas. Os resultados mostraram que as linhagens R1 e R3 apresentaram alta resistência à infecção do patógeno. No entanto, apenas a R3 foi resistente ao acúmulo de fumonisinas. Dessa forma, sugere-se que a ausência de relação entre intensidade da doença e níveis de fumonisinas seja fator inerente desse patossistema. Assim, não é possível assegurar que grãos assintomáticos quanto à infecção por F. verticillioides, estejam livres de contaminação por fumonisinas.

Maize infection by Fusarium verticillioides, the causal agent of Fusarium ear rot, can result in the production of mycotoxins of the fumonisin group. Genetic resistance is the most effective way to control this disease. Thus, the aim of this study was to evaluate tropical maize inbred lines as potential sources of resistance to F. verticillioides and production of fumonisins. Six maize inbred lines, three previously classified as resistant and three as susceptible to F. verticillioides, were inoculated with the pathogen and subsequently evaluated for ear rot severity, incidence of symptomatic grain and fumonisin concentration. Results showed that the lines R1 and R3 exhibited high resistance to the pathogen infection. However, only R3 was resistant to the accumulation of fumonisins. Therefore, it is suggested that absence of relationship between disease intensity and fumonisin production is inherent to this pathosystem. Thus, asymptomatic grains infected by F. verticillioides cannot be ensured to be free of contamination by fumonisins.

Citrus Variegated Chlorosis (CVC) caused by Xylella fastidiosa is one of the most important diseases for Brazilian citriculture. The CVC is a vascular disease with a long incubation period and symptoms similar to other disorders, and this factors difficult the CVC quantification in the field. Two methods of CVC assessment were compared in this study. The first method was based on a descriptive rating scale with four ratings, commonly used for the disease quantification. The second one was based on the incidence of symptomatic branches. The quantification of CVC through these two methods was carried out in a 10-year-old 'Natal' sweet orange orchard. The descriptive scale considered the symptoms of the entire plant. The disease incidence was evaluated in 36 branches in each plant. The assessments were conducted by three raters in 144 plants in July 2006 and July 2007 as well as in March and November 2008. The descriptive scale did not allow an accurate assessment and resulted in a moderate strength of agreement among the raters. On the other hand, the incidence quantification of CVC through the symptomatic branches showed high repeatability among the raters. We suggest the use of incidence of symptomatic branches as variable for CVC quantification.

O objetivo desse trabalho foi avaliar o efeito in vitro e in vivo dos sanificantes cloreto de benzalcônio (Fegatex®), biomassa cítrica (Ecolife40®) e ozônio no controle da podridão parda (Monilinia fructicola) e da podridão mole (Rhizopus stolonifer) em pêssegos das cultivares Aurora, Dourado e Flor da Prince. Cloreto de benzalcônio e biomassa cítrica, aplicados in vitro, ambos na concentração de 1000 mL L-1, inibiram totalmente o crescimento radial (micelial) de M. fructicola, porém nenhum deles foi eficiente no controle de R. stolonifer. Cloreto de benzalcônio aplicado de forma preventiva, na concentração de 3000 mL L-1, reduziu a podridão parda em frutos inoculados sem ferimentos. Quando aplicado de forma curativa em frutos não feridos esse produto foi eficiente em todas as concentrações testadas. Nenhum produto aplicado nos frutos de forma curativa foi eficiente no controle da podridão parda, quando a inoculação do fungo foi realizada através de ferimentos. Nenhum dos produtos foi eficiente no controle da podridão mole. O ozônio (0,1 mL L-1) não foi eficiente no controle das podridões parda e mole.

The purpose of this work was to study the in vitro and in vivo effects of the sanitizing products benzalkonium chloride (Fegatex®), citric biomass (Ecolife40®) and ozone gas on the control of brown rot (Monilinia fructicola) and soft rot (Rhizopus stolonifer) in peaches cultivars "Aurora", "Dourado" and "Flor da Prince". Benzalkonium chloride and citric biomass, both at 1000 mL L-1, completely inhibited the radial (mycelial) growth of M. fructicola, although none of them controlled R. stolonifer in vitro. The preventive use of benzalkonium chloride at 3000 mL L-1 reduced brown rot in non-injured peaches. Benzalkonium chloride applied as curative in non-injured peaches was effective against M. fructicola at all concentrations. None of the products tested curatively was effective in preventing the development of brown rot when the fungus was inoculated over fruit injuries. None of the products was effective in controlling soft rot. Ozone gas at 0,1 mL L-1 was not effective in controlling brown or soft rots in peaches.