ABSTRACT
The occurrence of powdery mildew (Microsphaera diffusa) in soybean (Glycine max L.) has increased in the last harvests. In order to study the efficiency of powdery mildew control due to the application of alternative products and conventional fungicide, trials were conducted in Ponta Grossa, PR, Brazil, during the 2013/2014 and 2014/2015 growing seasons. The design used was randomized blocks with four replications. The treatments for the experiments were: 1 - control; 2 - acibenzolar-S-methyl (Bion 500 WG®); 3 - calcium (Max Fruit®); 4 - Micronutrients: copper, manganese and zinc (Wert Plus®); 5 - Micronutrients: manganese, zinc and molybdenum (V6®); 6 - NK fertilizer (Hight Roots®); 7 - Ascophyllum nodosum (Acadian®) and 8 - fungicide (azoxystrobin + cyproconazole) (Priori XTRA®) with the addition of the adjuvant. Four applications of alternative products (phenological stages V3, V6, R1 and R5.1) and two of fungicide (phenological stages R1 and R5.1) were carried out. The parameters evaluated were powdery mildew severity and productivity. The severity data made it possible to calculate the area under the disease progress curve (AUDPG). Alternative products didn't reduce powdery mildew in the two harvests. The conventional fungicide treatment was the only one that controlled powdery mildew and didn't reduce the productivity in both experiments.
Subject(s)
Pesticides , Glycine max , Fungicides, Industrial , Erysiphe/pathogenicityABSTRACT
In recent years coffee productivity has been harmed by diseases caused by Colletotrichum gloeosporioides (Cg), for example, anthracnose, dieback and blister spot. Therefore, it has become necessary to develop alternative measures to control these diseases, since there are no fungicides registered in Brazil for their control. The aims of this work were: to evaluate the effect of potassium phosphite on the germination, fungal appressorium formation and mycelial growth of Cg and to verify this action in the reduction of disease severity of anthracnose in coffee leaves. The treatments used in an in vitro experiment were: potassium phosphite at doses of 1.25, 2.50, 5.0 and 10.0 mL.L-1, Acibenzolar-S-methyl at dose 0.1g.L-1 and Chlorothalonil fungicide at dose 2.0 g.L-1. In an in vivo experiment, beyond the treatments used in the in vitro experiment, we used a control sprayed with water without inoculation and another inoculated with Cg. Potassium phosphite at doses of 5.0 mL.L-1 and 10.0 mL.L-1 and the Chlorotalonil fungicide showed greater inhibition of conidial germination, greater inhibition of appressorium formation and further reduction of mycelial growth of the pathogen. In the in vivo experiment, Potassium phosphite at a dose of 10.0 mL.L-1 provided a greater reduction in disease severity, around 62.5%. This work demonstrated the potential of potassium phosphite in the management of diseases caused by fungi from the Colletotrichum complex in coffee plants.
Nos últimos anos a produtividade de café tem sido prejudicada por doenças causadas por Colletotrichum gloeosporioides (Cg), como por exemplo, antracnose, seca de ponteiros e mancha manteigosa. Portanto torna-se necessário desenvolver medidas alternativas de controle para essas doenças, visto que não existem fungicidas registrados no Brasil para seu controle. O presente trabalho teve como objetivos: avaliar o efeito do fosfito de potássio na germinação, formação de apressórios e no crescimento micelial de Cge verificar a ação do mesmo na redução da severidade da antracnose em folhas de cafeeiro. Os tratamentos utilizados no experimento in vitro foram: fosfito de potássio nas doses de 1,25; 2,50; 5,0 e 10,0 mL.L-1; acibenzolar-S-metil 0,1g.L-1; fungicida clorotalonil 2,0 g.L-1. Já in vivo, além dos tratamentos anteriores, foi utilizada uma testemunha pulverizada com água sem inoculação e outra inoculada com Cg.O fosfito de potássio nas doses de 5,0 mL.L-1 e 10,0 mL.L-1 e o fungicida clorotalonil proporcionaram maior inibição da germinação de conídios, maior inibição da formação de apressórios e maior redução do índice de velocidade de crescimento micelial do patógeno. No experimento in vivo, o fosfito de potássio na dose de 10,0mL.L-1 proporcionou maior redução na severidade da antracnose, em torno de 62,5 %.Este trabalho demonstrou o potencial do fosfito de potássio no manejo de doenças causadas por fungos do complexo Colletotrichum em cafeeiro.
Subject(s)
Phosphites , Colletotrichum , Coffea , FungiABSTRACT
Objetivou-se, neste trabalho, avaliar o efeito da aplicação de indutores na resistência de duas cultivares de soja à mosca-branca Bemisia tabaci biótipo B. O experimento foi conduzido no Departamento de Entomologia - UFLA. As sementes de soja, cultivar IAC-19 e MONSOY-8001, foram previamente tratadas com o fungicida captan. Foram testados os seguintes tratamentos: T1- irrigação no solo, ao redor das plantas de cada vaso, de 250 mL de solução de ácido silícico a 1 por cento; T2- pulverização das plantas, até o ponto de escorrimento, com solução a 0,3 por cento de acibenzolar-s-methyl; T3- pulverização das plantas, até o ponto de escorrimento, com calda a 0,24 por cento de pyraclostrobin+epoxiconazole e T4- testemunha. As plantas foram infestadas com 100 adultos da mosca-branca por vaso que liberados oito dias após a aplicação dos tratamentos. Avaliaram-se o número de ovos na face abaxial de cada folha, que foi marcada para posterior avaliação de ninfas; teores de taninos e de lignina; peso seco das raízes e da parte aérea. Não houve diferença para número de ovos e ninfas entre as cultivares de soja, porém, a viabilidade média de B. tabaci foi menor a cultivar IAC-19. O cultivar de soja IAC-19 demonstrou moderada resistência ao biótipo B de B. tabaci. A aplicação de silício ou acibenzolar-s-methyl induz um aumento no teor de lignina na cultivar de soja IAC-19.
The objective of this paper was to evaluate the effect of the application of inducers on the resistance of two soybean cultivars to the whitefly B. tabaci Biotype B. The experiment was carried out at the Entomology Department - UFLA. The soybean seeds of cultivars IAC-19 and MONSOY-8001 were previously treated with Captan fungicide. The following treatments were tested: T1- irrigating the soil around the plants of each pot with 250 mL of solution of 1 percent silicic acid; T2- spraying of the plants, to the 'point of dripping', with a solution of 0.3 percent acibenzolar-s-methyl; T3- spraying of the plants, to the 'point of dripping', with a solution of 0.24 percent pyraclostrobin+epoxiconazole, and T4- control. The plants were infested with 100 adult whiteflies that were released eight days after applying the treatments. The number of eggs on the abaxial face of each leaf, which was marked for further evaluation of nymphs, tannin and lignin contents, dry weight of the aerial parts and roots, was evaluated. There was no difference for the number of eggs and nymphs among the soybean cultivars. Nevertheless, the average survival rate of B. tabaci was lower on cultivar IAC-19. The application of silicon or acibenzolar-s-methyl induces an increase in lignin content in the soybean cultivar IAC-19.