Maristella Dalla Pria

Quantificação de componentes monocíclicos da antracnose do feijoeiro

Monocyclic components of anthracnose caused by Colletotrichum lindemuthianum were quantified on two bean (Phaseolus vulgaris) cultivars Rosinha and Carioca, in growth chambers. Incubation period and disease severity were assessed, at temperatures of 6, 10, 14, 17, 21, 25, 29 and 33 oC. Anthracnose did not develop at temperatures of 6 and 33 oC. The severity was highest at 17 oC and the shortest incubation periods occurred at 29 oC for the cv. Rosinha and 25 oC for the cv. Carioca. Beta function was fitted to data of disease severity at different temperatures. The effect of the leaf wetness duration (5, 6, 12, 18, 24, 30, 36, 42, 48 and 54 h) in disease severity was assessed as well. There was no increment in anthracnose severity of the bean for periods of wetness superior to 24 h. The variations of anthracnose in relation to the number of hours of leaf wetness were explained by the Richards model. The Beta-Richards function explained the combined effect of the temperature and leaf wetness duration in the severity of anthracnose, for both varieties.

Avaliação de inseticidas no controle de Myzus persicae (sulz.) (homoptera: aphididae) na cultura da alface

A field trial was carried out at Universidade Estadual de Ponta Grossa, State of Parana, Brazil, in 1999, to evaluate the efficiency of insecticides in controlling Myzus persicae (Sulz) on lettuce cv. Veronica. The experimental design was of completely randomized blocks with six treatments and four replications. The treatments consisted of thiamethoxam (50; 75 and 100 g i.a/ha) imidacloprid (140 g i.a/ha); pymetrozine (150 g i.a/ha) and control. The treatments were applied to seedlings grown in polyestyrene trays one day before the transplanting. The fitotoxicity, the number of aphids/plant, the percentage of plants with aphids and the efficiency of the insecticides were evaluated. Thiamethoxan at doses of 50; 75 and 100 g i.a/ha was efficient to control M. persicae from transplanting till 43 days after showing equal or higher efficiency than 98.6%, similar to imidacloprid. The pymetrozine was efficient to control M. persicae until 21 days after transplanting. Effects of fitotoxicity on lettuce plants were not observed. Higher fresh weight was observed in treated plants in comparison to the one of the control.

Épocas de colheita de umbelas e comprimento da haste floral no rendimento e no potencial fisiológico de sementes de cebola

The Parana State (Brazil) contributes significantly to the Brazilian onion production. However, this State imports all needed onion seeds. The effect of umbels harvest period, and harvesting with or without the seed stalk were evaluated. Treatments resulted from the combination of three harvesting periods (with green capsules, at the beginning of capsule opening and with 10% opened capsules), combined with umbels on 15 cm long stalks or without stalks, arranged in a factorial scheme 3x2. The experimental design was a randomized blocks, with four replications. The bulbs of Crioula cultivar proceeded from EPAGRI, Santa Catarina State, and were planted on July/2002, in Imbituva, Parana State, under protected cultivation. At flowering, four umbels per plot were marked to future use in the evaluations. The number of total of fertile flowers (capsules) and unfertile flowers were counted on each harvested umbel. Seeds were detached from capsules and the number of seeds per capsule obtained, besides the yield per umbel, weight of 100 seeds, germination and vigor of the seeds. Harvesting umbels with the seed stalk had no effect on the seed yield and on seed physiological potential. The harvesting period presented significant effect on the amount and quality of the harvested seeds. The best harvesting period was at the beginning of capsule opening or when 10% of capsules were opened, resulting in higher number of seeds/umbel, higher seed yield/umbel and higher seed weight per capsule. The average yield was 2.9 g/umbel besides higher vigor (90.25%) and germinability (85.25%). Harvesting at the beginning of capsule opening helps to avoid the lost of seeds by thresh or diseases.

Quantificação de componentes monocíclicos da mancha angular do feijoeiro

Monocyclic components of angular leaf spot, were quantified on two bean (Phaseolus vulgaris) cultivars Rosinha and Carioca in growth chambers. Incubation period, disease severity and lesion growth rate were assessed, at temperatures of 6, 10, 14, 17, 21, 25, 29 and 33 oC. No angular leaf spot symptoms occurred at 6 and 29 oC. Severity for angular leaf spot was high between temperatures of 20 and 25 oC, and the incubation period for both varieties tested was favoured at a temperature of 25 oC. This temperature also provided the greatest lesion growth rate and these data were adjusted by a first grade equation in function of the temperature. The effect of the leaf wetness duration (5, 6, 12, 18, 24, 30, 36, 42, 48 and 54 h) in the severity of disease symptoms was studied as well. Severity for the angular leaf spot increased with the wetness duration period to the maximum of 54 h tested. The variations of angular leaf spot in relation to the number of hours of leaf wetness were explained by the Richards model. The Beta-Richards function explained the combined effects of the temperature and leaf wetness duration in the severity of angular leaf spot, for both varieties.