Alex Queiroz Cysne

Ocorrência endofítica de Lasiodiplodia theobromae em tecidos de cajueiro e sua transmissão por propágulos

Lasiodiplodia theobromae, agent of gummosis and black branch dieback of cashew, is the most important disease of cashew crop in semi-arid regions of northeastern Brazil. This pathogen is a well known fungus in many host plants as capable of colonizing their tissues without showing disease symptoms. This feature ensures great epidemiologic importance as considering tactics for disease avoidance. The occurrence of cashew gummosis in geographically isolated areas reinforces the seed and scion borne pathogen hypothesis. The objectives of this study were to determine the ability of L. theobromae to survive in cashew tissues without showing symptoms and to evaluate plant propagating materials (seed and scion) as source of primary inoculum. The presence of the fungus at different distances from the canker throughout the stem in both ascendant and descendent direction was determined by plating infected tissue samples. In another study, transplanting materials were produced by using rootstocks from seeds sampled either from healthy and gummosis-infected plants and grafted with scions also from healthy and gummosis-infected plants, making a four set of treatments. These plants were transplanted into a commercial cashew farm located in Pio IX, County, Piaui State, highly conducive for disease outbreak. L. theobromae was isolated from up to 80 cm distance from canker in both directions. Greater gummosis incidence was observed in plots initiated by rootstock and scion originated from diseased plants. These findings showed the endophytic behavior of L. theobromae in cashew tissues and the importance of rootstock seed as a source of primary inoculum.

Interação enxerto e porta-enxerto na incidência da resinose do cajueiro

A expansao do cajueiro-anao-precoce no Brasil vem promovendo baixa diversidade genetica dos genotipos usados como enxerto e porta-enxerto, ensejando vulnerabilidade da cultura as vicissitudes bioticas como a resinose (Lasiodiplodia theobromae), principal doenca do cajueiro no semiarido nordestino. Estima-se que cerca de meio milhao de mudas de cajueiro-anao-precoce sejam produzidas anualmente, sendo a grande maioria delas produzida de propagulos enxertados sobre plântulas oriundas de sementes do clone CCP 06. A principal estrategia de manejo da resinose e o plantio de clones resistentes. Entretanto, entre os aspectos que contribuem para sucessivas epidemias da resinose, destaca-se a falta de estudos de interacoes genotipicas entre enxerto e porta-enxerto. Este estudo objetivou avaliar o efeito de combinacoes de clones de cajueiro-anao-precoce usados como enxerto e porta-enxerto na incidencia da resinose. Sementes de plantas de polinizacao aberta de seis clones selecionados foram usadas para producao de porta-enxerto. Os clones comerciais CCP 76 (suscetivel) e BRS 226 (resistente) foram usados como enxertos. O experimento foi realizado obedecendo ao delineamento de blocos ao acaso, no esquema fatorial 2 x 6, com quatro repeticoes e nove plantas por parcela do tipo quadrada, sob condicoes de elevada pressao da doenca, em Pio IX-PI. Tres anos apos o plantio definitivo, a incidencia (I) e a severidade (S) (escala de 0 a 4) da resinose foram superiores no clone CCP 76 (I = 97% e S=2,10) em relacao ao BRS 226 (I = 33% e S=0,36), independentemente do porta-enxerto. O clone CP 06 como porta-enxerto foi o unico que reduziu a incidencia e a severidade da resinose, independentemente do genotipo do enxerto. Este clone foi capaz de reduzir a severidade da resinose do clone CCP 76 (S=2,10) como enxerto em quase 30%.

Flutuação populacional de Rhynchophorus palmarum (L.) (Coleoptera: Curculionidae) em palmeiras oleíferas no Amazonas

The borers are one of the main pests of palms due to their direct and indirect damages which may result in plant death. The population survey of this insect is important in order to properly handle its control. This study aimed to monitor the population dynamic of Rhynchophorus palmarum in commercial plantations of Elaeis guineensis Jacq. and E. oleifera (HBK) Cortes, in the Amazonas State. For capturing insects, baited traps containing pieces of sugarcane stalk and aggregation pheromone were distributed around the plantation, in the Experimental Station of Rio Urubu, Rio Preto da Eva, AM, Brazil. The data were evaluated for the annual (2005 to 2009) incidence of insects, monthly incidence and frequency of capture. Comparing the years, it was found that the largest amount of insects collected was in 2005, being observed a reduction in captured insects by 2007, then the amount of captured insects increased in 2008 and 2009. For months within a given year no difference was found on the population dynamic of this insect (P > 0,05). Approximately 40% of the collections exceeded four insects, being observed similar behavior in the capture frequency of years studied.

Método de avaliação da resistência de clones de cajueiro à resinose

ABSTRACT Gummosis, caused by Lasiodiplodia theobromae , is an importantdisease of cashew plants in Brazil. Genetic resistance is a promisingcontrol method, however, the selection of resistant genotypes underfield conditions is both expensive and time consuming. This work wasdeveloped in order to define a method for the early selection of clonesresistant to gummosis by testing different methodologies for inoculumproduction and pathogen inoculation. The evaluated techniques includedbevel, spore suspension injection and toothpick methods in two cashewclones with different reactions to gummosis: BRS 226 – resistant and CP76 – susceptible. The effect of water stress induced by increasing the Cardoso, J.E.; Cysne, A.Q.; Costa, J.V.T.A.; Viana, F.M.P. Screening method for selection of cashew clone resistant to gummosis . SummaPhytopathologica, v.36, n.4, p.329-333, 2010. Keywords: Lasiodiplodia theobromae , inoculation method, inoculum production. Palavras-chave adicionais: Lasiodiplodia theobromae

Fungos associados a sementes híbridas interespecíficas de dendê em função da assepsia e do beneficiamento.

A micofauna de sementes hibridas de dende (cv. BRS Manicore) foi identificada e quantificada, levando em consideracao as diferentes etapas de beneficiamento e o efeito do hipoclorito de sodio no pre-tratamento para teste de sanidade destas sementes. Foi realizada a identificacao dos fungos nas etapas de despolpe, secagem e armazenamento, com e sem assepsia com hipoclorito de sodio.