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Title: Control of milk weed (Euphorbia heterophylla) with Helminthosporium sp.
Authors: YORINORI, J. T.
Date Issued: 1989
Citation: In: INTERNATIONAL SYMPOSIUM BIOLOGICAL CONTROL OF WEEDS, 7., 1988. Rome. Proceedings... Rome: Institute Sperimentale per la Patologia Vegetale/MAF, 1989. p. 571-576.
Description: In the 1980/81 crop season the National Soybean Research Center of EMBRAPA, Brazil, initiated a biological control program for milk weed, Euphorbia heterophylla. It is estimated that ca. 200.000 ha of cropland, mainly soybeans, is infested, demanding an expenditure of ca. US$ 3.7 million worth in chemicals for 1987/88 season. A naturally-occurring Helminthosporium species was found to be virulent on most populations of the weed. The majority of the populations are uniformly susceptible, some are uniformly immune and others are mixed-susceptible, immune and plants with varying degrees of infection. Germination of spores in mixtures with herbicides bentazon, sethoxydin and surfactant was unaffected, but was severely affected by fomesafen and the surfactant energic at the recommended rates. Germination was not affected when in mixtures with Bacillus thuringiensis, Baculovirus anticarsia and carbaryl. Dried spores kept for 14 monts in sealed test tubes were slow to germinate in water but reached 83% after 24 h. When spores were dry-formulated in lactose and stored for six months under laboratory conditions, germination reached 93% after 4 h incubation, and 99% after 24 h. Time of field application (8:00, 12:00 and 16:00), with temperatures varying from 23.8, 27,7 and 32.3oC, respectively, did not interfere with degree of infection, indicating that the fungus can be applied at any time of the day. Field application was adversely affected by low relative humidity but timely application under adequate conditions ...
Thesagro: Controle Biológico
Euphorbia Heterophylla
NAL Thesaurus: Brazil
biological control
Keywords: Planta daninha
Helminthosporium sp
Language: Ingles
Type of Material: Separatas
Access: openAccess
Appears in Collections:Artigo em anais de congresso (CNPSO)

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