RESUMO: A deriva dos herbicidas carfentrazone-ethyl e glyphosate pode afetar o crescimento inicial do eucalipto. Este trabalho objetivou avaliar o efeito da deriva de carfentrazone-ethyl e glyphosate sobre a fotossíntese, a morfoanatomia foliar e o crescimento inicial de dois clones de Eucalyptus grandis. Foram realizados dois ensaios em esquema fatorial 2 x 4, sendo o fator 1 representado por dois clones de E. grandis, e o fator 2, por quatro subdoses dos herbicidas (testemunha, 86,4 g e.a. ha-1 de glyphosate, 3,0 g e.a. ha-1 de carfentrazone-ethyl e a mistura de 86,4 g e.a. ha-1 de glyphosate + 3,0 g e.a. ha-1 de carfentrazone-ethyl). A aplicação dos herbicidas foi feita simulando deriva no terço inferior da copa das mudas. As avaliações foram realizadas 23 dias após aplicação. Os dois clones apresentaram alterações morfoanatômicas, como erosão de ceras epicuticulares, degeneração de células epidérmicas e parenquimáticas, sobretudo quando expostas à subdose de carfentrazone-ethyl ou de sua mistura com glyphosate. O clone CLR 383 foi o mais afetado pelos herbicidas testados e apresentou maior injúria, menor crescimento inicial, menor massa seca e maior redução na taxa fotossintética quando tratado com a mistura, seguida das subdoses de carfentrazone-ethyl e glyphosate, respectivamente. O crescimento inicial em altura, a massa seca e a fotossíntese do clone CLR 384 não foram afetados pela subdose isolada de carfentrazone-ethyl. Os resultados deste trabalho permitem concluir que os dois herbicidas, aplicados de forma isolada ou em mistura, reduzem o crescimento inicial, a massa seca e a fotossíntese em plantas de eucalipto.

ABSTRACT: Drift of the herbicides carfentrazone-ethyl and glyphosate may affect the initial growth of eucalyptus. This study aimed to assess the effect of carfentrazone-ethyl and glyphosate drift on photosynthesis, leaf morphoanatomy, and initial growth of two clones of Eucalyptus grandis. Two experiments were carried out in a 2 x 4 factorial scheme, in which factor 1 was represented by two clones of E. grandis and factor 2 by four herbicide underdoses (control, 86.4 g a.e. ha-1 of glyphosate, 3.0 g a.e. ha-1 of carfentrazone-ethyl, and the mixture of 86.4 g a.e. ha-1 of glyphosate + 3.0 g a.e. ha-1 of carfentrazone-ethyl). Herbicide application was carried out by simulating the drift in the lower third of seedling canopy. Assessments were performed 23 days after herbicide application. Both clones presented morphoanatomical changes such as erosion of epicuticular waxes and degeneration of epidermal and parenchymal cells, especially when exposed to carfentrazone-ethyl underdose or its mixture with glyphosate. The clone CLR 383 was the most affected by the tested herbicides and presented the highest injury, lowest initial growth, lowest dry matter, and highest reduction of photosynthetic rate when treated with herbicide mixture, followed by carfentrazone-ethyl and glyphosate underdoses. The initial growth, dry matter, and photosynthesis of the clone CLR 384 were not affected by the carfentrazone-ethyl underdose. Thus, both herbicides applied in isolation or in a mixture reduced the initial growth, dry matter, and photosynthesis of eucalyptus.

O glyphosate é o herbicida mais usado no controle de plantas daninhas em eucalipto, atuando diretamente na rota do ácido chiquímico, principal via de formação de compostos ligados aos mecanismos de defesa das plantas, como: lignina, ácido salicítico e fitoalexinas. Assim, o contato do glyphosate com as folhas do eucalipto pode levar a conseqüências importantes sobre a resistência a doenças. Objetivou-se neste estudo avaliar o envolvimento do glyphosate, via deriva, na severidade da ferrugem causada por Puccinia psidii em genótipos de eucalipto com diferentes níveis de resistência ao patógeno. Para isso, mudas de quatro clones - dois heterozigotos resistentes à ferrugem (UFV01 e UFV02) e dois homozigotos suscetíveis (UFV03 e UFV04) - foram submetidas às subdoses de 0 (testemunha); 28,8; 57,6; 86,4; e 115,2 g ha-1 de glyphosate, simulando deriva. Três dias após a aplicação do glyphosate, as plantas foram inoculadas com o isolado monopustular UFV1 de P. psidii, obtido de Eucalyptus grandis, na região de Itapetininga, SP. Aos 21 dias após a inoculação, foram avaliados a severidade de ferrugem, utilizando-se uma escala diagramática com quatro classes (S0 e S1 resistentes à ferrugem e S2 e S3 suscetíveis), o número de pústulas cm-2 de área foliar, a área foliar lesionada pela ferrugem, o número médio de urediniósporos cm-2 de área foliar, o número médio de urediniósporos/pústula e a porcentagem de intoxicação pelo glyphosate. O clone UFV04 foi o mais sensível ao glyphosate, enquanto o UFV01 apresentou maior tolerância ao herbicida. O glyphosate não alterou o nível de resistência à ferrugem nos genótipos resistentes (UFV01 e UFV02) que apresentaram ausência de pústulas nas folhas, tanto em plantas expostas à deriva quanto nas testemunhas. Para os demais clones, manteve-se a suscetibilidade à ferrugem, embora, com o aumento das doses de glyphosate, tenha se observado diminuição da severidade da doença. Conclui-se que o glyphosate não afetou a resistência do eucalipto a Puccinia psidii, ocorrendo diminuição da severidade da doença em plantas expostas ao glyphosate via deriva, e que existe tolerância diferencial entre os clones ao herbicida.

Glyphosate is the herbicide most applied on eucalyptus plantations for weed control, acting directly on the shikimic acid pathway, the main via for the formation of compounds connected with the natural defenses of the plant, such as lignin, salicytic acid and phytoalexins. Thus, glyphosate contact with the leaves of the plant through drift may have important consequences for disease resistance. The aim of our research was to evaluate glyphosate drift involvement with severity of rust caused by Puccinia psidii in genotypes with different levels of resistance to the pathogen, after inoculation in a controlled environment. Seedlings of four clones, two heterozygote clones resistant to rust (UFV01 and UFV02) and two homozygote clones susceptible to rust (UFV03 and UFV04) were submitted to sub-doses of 0 (control); 28.8, 57.6, 86.4 and 115.2 g ha-1 of glyphosate simulating drift. Three days after glyphosate application, the plants were inoculated with UFV01 isolated from P. psidii obtained from Eucalyptus grandis in the Itapetininga region. On day 21 after inoculation, the following parameters were evaluated: rust intensity, by means of a diagrammatic scale with four classes of severity (SO and S2 resistant to rust and S2 and S3 susceptible to rust), number of pustules per leaf area, area affected by rust, average number of urediniospores cm-2, glyphosate percentage intoxication, and average number of urediniospores/pustule. Clone UFV04 was found to be the most susceptible while UFV01 was the most tolerant to the herbicide. Drift did not change the level of resistance to rust with respect to the resistant genotypes (UFV01 and UFV02) which presented no pustule both in plants exposed to drift and control plants. Susceptibility was maintained for the other clones, with a higher pustule density and higher percentage of affected area becoming evident for clone UFV03. For some clones susceptible to rust, rust severity decreased with glyphosate dosage increase. It was concluded that glyphosate did not affect eucalyptus resistance to Puccinia psidii and that there is differential tolerance to the herbicide among the clones.

Extraction and isoenzyme analysis of four isolates of Arthrobotrys including A. musiformis, A. robusta and A. conoides were conducted. Among the 14 enzymes studied by starch gel electrophoresis, using morpholine-citrate as gel/electrode buffer, the following nine enzymes showed interpretable banding patterns: <!-- $MVD$:face("Symbol") --><FONT FACE="Symbol">a</font>-esterase, fumarase, hexokinase, isocitrate dehydrogenase, leucine aminopeptidase, malate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucomutase and phosphoglucoisomerase. All isolates studied displayed typical isoenzyme phenotypes for each species. Two isolates of A. conoides differed in their <!-- $MVD$:face("Symbol") --><FONT FACE="Symbol">a</font>-isoesterase banding patterns, but no differences were observed for the other enzymes. The assay was satisfactory for enzyme extraction and resolution of Arthrobotrys and could be used in future taxonomic and genetic studies of this organism