Escala diagramática de dano de Aceria guerreronis Keifer (Acari: Eriophyidae) em coqueiro / Diagrammatic scale of Aceria guerreronis Keifer (Acari: Eriophyidae) damage in coconut

Aceria guerreronis Keifer é importante praga do coqueiro no mundo. Dada a falta de métodos padronizados para a quantificação dos danos causados por esse eriofiídeo, uma escala diagramática com níveis de 1, 2, 4, 8, 16, 32, 48 e 70% de danos foi elaborada e testada para precisão e reprodutibilidade das estimativas. Para validar a escala, frutos com diferentes níveis de dano foram previamente avaliados com o programa Assess e submetidos à avaliação por 10 avaliadores inexperientes com e sem a escala (1ª avaliação) e sete dias após (2ª avaliação) com os mesmos avaliadores, empregandose as fotos digitalizadas dos mesmos frutos com seqüência diferente. A acurácia e a precisão de cada avaliador foram determinadas por regressão linear simples entre o dano observado e estimado. Sem a utilização da escala, sete de 10 avaliadores superestimaram o nível de dano, sendo pouco precisos. No entanto, avaliadores utilizando a escala obtiveram melhores níveis de acurácia e precisão. Osavaliadores apresentaram níveis mais elevados de reprodutibilidade das estimativas com a utilização da escala comparada às avaliações sem a escala. A escala foi utilizada para determinar a relação entre a infestação e o dano causado por A. guerreronis. A relação entre infestação e níveis de dano apresentou elevada precisão (R2 = 99,87%, P < 0,0001) pela equação lny = 4,948 - 0,121 x + 1,789 lnx. Portanto,os resultados comprovam que é possível estimar a população de A. guerreronis nos frutos de coco infestados com a utilização da escala diagramática.

Aceria guerreronis Keifer is an important pest of coconut worldwide. Due to the lack of standardized methods to quantify damage of this eryophyid, a diagrammatic scale with indices of 1, 2, 4, 8, 16, 32, 48 and 70% of damage caused by A. guerreronis was elaborated and tested to accuracy, precision and reproduction of the estimations. To validate the scale, fruits with different levels of damage were previously measured with the program Assess and submitted to 10 inexperienced evaluators with or without the scale (1ª evaluation) and seven days after (2ª evaluation) with the same evaluators, using digitized pictures of the same fruits in a different sequence. The accuracy and precision of each evaluator was determined through linear regression between observed and estimated damage. Without using the scale, evaluators were less precise as seven out of 10 overestimated the damage, while evaluators provided with the scale were much more accurate. Also, evaluations with the aid of the scale were much more reproducible than without the scale. The scale was used to determine the relationship between infestation and damage levels caused by A. guerrerronis. The relationshipbetween infestation and damage fi tted by the equation lny = 4.948 - 0.121x + 1.789 lnx (R2 = 99.87%, P < 0.0001). Therefore, these fi ndings show that it is possible to estimate A. guerreronis population density on infested coconut fruits by using the diagrammatic scale.

Antagonism of Yeasts to Xanthomonas Campestris PV. Campestris on Cabbage Phylloplane in field

Twenty yeast isolates, obtained from cabbage phylloplane, were evaluated for antagonistic activity against Xanthomonas campestris pv. campestris, in field. Plants of cabbage ev. Midori were pulverized simultaneously with suspensions of antagonists and pathogen. After 10 days, plants were evaluated through percentage of foliar area with lesions. Percentage of disease severity reduction (DSR per cent) was also calculated. Yeast isolates LR32, LR42 and LR19 showed, respectively, 72, 75 and 79 (per cent) of DSR. These antagonists were tested in seven different application periods in relation to pathogen inoculation (T1=4 d before; T2=simultaneously; T3=4 d after; T4=4 d before + simultaneously; T5=4 d after + simultaneously; T6=4 d before + 4 d after; T7=4 d before + simultaneously + 4 d after). The highest DSRs were showed by LR42 (71 per cent), LR42 (67 per cent), LR35 (69 per cent) and LR19 (68 per cent) in the treatments T7, T4, T5, and T6, which significantly differed from the others. The same yeast antagonists were also tested for back rot control using different cabbage cultivars (Fuyutoyo, Master-325, Matsukaze, Midori, Sekai I and Red Winner). The DSRs varied from 58 to 61 (per cent), and there was no significant difference among cultivars

Biocontrole pós-colheita da podridäo de Lasiodiplodia em frutos de manga por leveduras saprofíticas / Postharvest biocontrol of Lasiodiploidia rot of mango fruits by saprophytic yeasts

Among eigtheen yeast isolates studied as potential agents for biocontrol of stem-end rot on mango fruits caused by Lasiodiplodia theobromae, five were selected for testing in relation to three pathogen concentrations (1x10ü, 1x10 elevada à quarta and 1x10 elevada à quinta conidia/ml). The isolate LM-5 (Candida maritima) showed high control level at all pathogen concentrations. When tested against five pathogen isolates, LM-5 again demonstrated high control efficiency, and at in vitro test, highlyinhibited L.theobromae spore germination. The isolate LM-5 demonstrated great potential as agent for postharvest biocontrol of mango rot

Bacillus subtilis as a potential biocontrol agent of the northern leaf blight of corn

Quatro isolados de Bacillus subtilis (AP-3, AP-420, IF-36 e IF-82) foram estudados como agentes potenciais para o biocotrole da queima das folhas do milho, causada por Exserohilum turcicum. Em condiçöes de casa-de-vegetaçäo os isolados bacterianos demonstraram boa eficiência para o biocontrole. Considerando a média de 3 períodos de aplicaçäo, o isolado AP-420 foi o mais eficiente. A aplicaçäo dos antagonistas simultaneamente com a inoculaçäo de E. turcicum apresentou os melhores resultados. Em condiçöes de laboratório as bactérias produziram metabólitos extracelulares, näo-voláteis e difusíveis que inibiram o crescimento micelial e a germinaçäo de conídios de E. turcicum