Paulo Roberto Kuhnem Junior

Modelo de ponto crítico para estimar danos de doenças foliares do trigo em patossistema múltiplo

A critical-point model to estimate damage caused by wheat leaf diseases in a multiple pathosystem Wheat leaf diseases cause damage by reducing photosynthetic activity in leaves. The objective was to obtain damage model equations for a wheat multiple pathosystem, by examining the relation between grain yield and the incidence of leaf diseases at different plant growth stages. The experiments were carried in Lages and Sao Jose do Cerrito, SC, during the 2005/06 and 2006/07 crop seasons with cultivars Onix and BRS Louro. The gradient of disease incidence was obtained by the number of fungicide applications (one, two, and three) and three different fungicide rates: azoxystrobin+cyproconazol (40+16, 60+24 and 80+32 g of a.i. ha -1

Época de aplicação e desempenho de fungicidas no controle da giberela em trigo

The chemical control of the wheat scab can be affected by time of application and fungicide. In the 2004 growing season, the fungicides were applied in the plant growth stage of beginning of flowering, half of complete flowering and beginning of soft dough stage. In the 2005 growing season, one only fungicides application was done in the beginning of the flowering with a larger number of fungicides. The applications were done with manual spray, with CO2 gas pressure in an outflow of 200L ha-1. The intensity of wheat scab was quantified by the incidence, severity and index of giberela. Grain yield, weight of a thousand grains and the incidence of Fusarium graminearum in the grains were also evaluated. The high porcentual of wheat scab control occurred when the application was done in the beginning of the flowering. The fungicides metconazol (0.09L i.a. ha-1), tebuconazol (0.15), trifloxystrobin+tebuconazol (0.075+0.15), azoxystrobin+ciproconazol (0.060+0.024) and pyraclostrobin+epoxiconazol (0.099+0.037) reduced significantly the intensity of giberela wheat, obtaining average control of 46% on incidence, 46.6% on severity and 71.2% on index of giberela wheat. These fungicides showed grain yield average of 23.4%, but a low efficiency on F. graminearum infection control in grains.

Survey, survival and control of Alternaria alternata in wheat seeds

The fungus Alternaria alternata was quantified in 75 wheat seed samples collected from three different regions of southern Brazil for Cropping and Use Value (CUV) I, II and III. Fungal presence was evaluated in two hundred disinfested seeds per sample before sowing in a potato-dextrose-agar medium + antibiotic (PDA+A). Fungus survival was evaluated every 45 days for 180 days for three seed batches from six wheat cultivars stored in propylene bags in a storehouse, with air temperature varying between 18 to 22 °C and relative air humidity around 60%. The efficacy of carboxin+thiram, difenoconazol, thiram, triadimenol, triticonazol and triticonazol + iprodione fungicides to control A. alternata was determined. A. alternata was detected in all the samples with an incidences of 39.6 %, 38.8% and 35.9% for the CUV I, CUV II and CUV III regions, respectively. The highest mean incidence of the fungus was found in the CUV I region, the coolest and most humid, and was significantly different from the other two regions. The average reduction in A. alternata viability in the wheat cultivar seeds was 49.5% during the 180 days of storage (inter-harvest period), demonstrating that infected seeds are the primary inoculum source for the fungus. The triticonazol + iprodione fungicide mixture efficiently controls A. alternata.

Ferrugem em framboesa no estado de Santa Catarina

Folhas e frutos de framboesa (Rubus idaeus L.) da cultivar Batum coletados de plantas do pomar do Centro de Ciencias Agroveterinarias, CAV, municipio de Lages-SC, apresentando pustulas de ferrugem, foram encaminhados para analise no Laboratorio de Fitopatologia do CAV. A diagnose indireta indicou a presenca de pustulas com uma massa de esporos de cor amarela na face abaxial das folhas e superficie dos frutos. No exame ao microscopio, observou-se uredia e urediniosporos pequenos, obovados ou elipsoides, medindo 12,5-17,5 x 15,0-30,0 µm sobre a epiderme da folha e frutos, sem a presenca de telias. Suspensao de urediniosporos (50.000 esporos mL-1) em agua esterilizada foi pulverizada em folhas destacadas da mesma cultivar, mantidas por 24 h no escuro e 12 h de fotoperiodo em câmara umida a 20oC. Folhas-controle foram pulverizadas com agua esterilizada. Apos 10 dias detectaram-se uredias contendo urediniosporos na face abaxial das folhas, cujas caracteristicas morfologicas e mensuracao dos urediniosporos, sintomas e patogenicidade permitiram a identificacao do agente causal como sendo Pucciniastrum americanum (Farl.) Arthur pela primeira vez no Estado de Santa Catarina.RESUMO - Folhas e frutos de framboesa (Rubus idaeus L.) da cultivar Batum coletados de plantas do pomar do Centro de Ciencias Agroveterinarias, CAV, municipio de Lages-SC, apresentando pustulas de ferrugem, foram encaminhados para analise no Laboratorio de Fitopatologia do CAV. A diagnose indireta indicou a presenca de pustulas com uma massa de esporos de cor amarela na face abaxial das folhas e superficie dos frutos. No exame ao microscopio, observou-se uredia e urediniosporos pequenos, obovados ou elipsoides, medindo 12,5-17,5 x 15,0-30,0 µm sobre a epiderme da folha e frutos, sem a presenca de telias. Suspensao de urediniosporos (50.000 esporos mL -1 ) em agua esterilizada foi pulverizada em folhas destacadas da mesma cultivar, mantidas por 24 h no escuro e 12 h de fotoperiodo em câmara umida a 20oC. Folhas-controle foram pulverizadas com agua esterilizada. Apos 10 dias, detectaram-se uredias contendo urediniosporos na face abaxial das folhas, cujas caracteristicas morfologicas e mensuracao dos urediniosporos, sintomas e patogenicidade permitiram a identificacao do agente causal como sendo Pucciniastrum americanum (Farl.) Arthur pela primeira vez no Estado de Santa Catarina. Termos para Indexacao: diagnose, fungo, ocorrencia, Pucciniastrum americanum, Rubus idaeus.Leaves and fruits of red raspberry (Rubus idaeus L.) of the cultivar Batum collected from the Agriculture and Life Science College - CAV orchard in Lages, SC, presenting rust pustules were analyzed in the CAV Plant Pathology Laboratory. Indirect diagnosis indicated in the abaxial side of the infected leaves and fruits surface pustules filled with masses of yellow spores. Under microscope exam, uredia and small, obovate or elliptical and averaged 12,5-17,5 x 15,0-30,0 µm urediniospores become evident in leaves and fruit surface. Telia were not observed. Urediniopores (50.000 esporos mL-1) were suspended in sterile water and sprayed onto same cultivar leaves that were maintained in a darkened mist chamber at 20oC for 24 h and transferred to a 20oC and 12 h light cycle chamber. Control leaves received sterile water only. After 10 days, sporulating uredia with urediniospores were produced on abaxial leaves and according to morphological characteristic of urediniopores, symptoms and pathogenicity, this is the first report of Pucciniastrum americanum (Farl.) Arthur in Santa Catarina State, Brazil.

Red raspberry rust in Santa Catarina state

Folhas e frutos de framboesa (Rubus idaeus L.) da cultivar Batum coletados de plantas do pomar do Centro de Ciencias Agroveterinarias, CAV, municipio de Lages-SC, apresentando pustulas de ferrugem, foram encaminhados para analise no Laboratorio de Fitopatologia do CAV. A diagnose indireta indicou a presenca de pustulas com uma massa de esporos de cor amarela na face abaxial das folhas e superficie dos frutos. No exame ao microscopio, observou-se uredia e urediniosporos pequenos, obovados ou elipsoides, medindo 12,5-17,5 x 15,0-30,0 µm sobre a epiderme da folha e frutos, sem a presenca de telias. Suspensao de urediniosporos (50.000 esporos mL-1) em agua esterilizada foi pulverizada em folhas destacadas da mesma cultivar, mantidas por 24 h no escuro e 12 h de fotoperiodo em câmara umida a 20oC. Folhas-controle foram pulverizadas com agua esterilizada. Apos 10 dias detectaram-se uredias contendo urediniosporos na face abaxial das folhas, cujas caracteristicas morfologicas e mensuracao dos urediniosporos, sintomas e patogenicidade permitiram a identificacao do agente causal como sendo Pucciniastrum americanum (Farl.) Arthur pela primeira vez no Estado de Santa Catarina.RESUMO - Folhas e frutos de framboesa (Rubus idaeus L.) da cultivar Batum coletados de plantas do pomar do Centro de Ciencias Agroveterinarias, CAV, municipio de Lages-SC, apresentando pustulas de ferrugem, foram encaminhados para analise no Laboratorio de Fitopatologia do CAV. A diagnose indireta indicou a presenca de pustulas com uma massa de esporos de cor amarela na face abaxial das folhas e superficie dos frutos. No exame ao microscopio, observou-se uredia e urediniosporos pequenos, obovados ou elipsoides, medindo 12,5-17,5 x 15,0-30,0 µm sobre a epiderme da folha e frutos, sem a presenca de telias. Suspensao de urediniosporos (50.000 esporos mL -1 ) em agua esterilizada foi pulverizada em folhas destacadas da mesma cultivar, mantidas por 24 h no escuro e 12 h de fotoperiodo em câmara umida a 20oC. Folhas-controle foram pulverizadas com agua esterilizada. Apos 10 dias, detectaram-se uredias contendo urediniosporos na face abaxial das folhas, cujas caracteristicas morfologicas e mensuracao dos urediniosporos, sintomas e patogenicidade permitiram a identificacao do agente causal como sendo Pucciniastrum americanum (Farl.) Arthur pela primeira vez no Estado de Santa Catarina. Termos para Indexacao: diagnose, fungo, ocorrencia, Pucciniastrum americanum, Rubus idaeus.Leaves and fruits of red raspberry (Rubus idaeus L.) of the cultivar Batum collected from the Agriculture and Life Science College - CAV orchard in Lages, SC, presenting rust pustules were analyzed in the CAV Plant Pathology Laboratory. Indirect diagnosis indicated in the abaxial side of the infected leaves and fruits surface pustules filled with masses of yellow spores. Under microscope exam, uredia and small, obovate or elliptical and averaged 12,5-17,5 x 15,0-30,0 µm urediniospores become evident in leaves and fruit surface. Telia were not observed. Urediniopores (50.000 esporos mL-1) were suspended in sterile water and sprayed onto same cultivar leaves that were maintained in a darkened mist chamber at 20oC for 24 h and transferred to a 20oC and 12 h light cycle chamber. Control leaves received sterile water only. After 10 days, sporulating uredia with urediniospores were produced on abaxial leaves and according to morphological characteristic of urediniopores, symptoms and pathogenicity, this is the first report of Pucciniastrum americanum (Farl.) Arthur in Santa Catarina State, Brazil.