Fusarium wilt of cotton: Population diversity and implications for management

Fusarium wilt of cotton, caused by the fungus Fusarium oxysporum Schlechtend. f. sp. vasinfectum (Atk.) Snyd. & Hans, was first identified in 1892 in cotton growing in sandy acid soils in Alabama (8). Although the disease was soon discovered in other major cotton-producing areas, it did not become global until the end of the next century. After its original discovery, Fusarium wilt of cotton was reported in Egypt (1902) (30), India (1908) (60), Tanzania (1954) (110), California (1959) (33), Sudan (1960) (44), Israel (1970) (27), Brazil (1978) (5), China (1981) (17), and Australia (1993) (56). In addition to a worldwide distribution, Fusarium wilt occurs in all four of the domesticated cottons, Gossypium arboretum L., G. barbadense L., G. herbaceum L., and G. hirsutum L. (4,30). Disease losses in cotton are highly variable within a country or region. In severely infested fields planted with susceptible cultivars, yield losses can be high. In California, complete crop losses in individual fields have been observed (R. M. Davis, unpublished). Disease loss estimates prepared by the National Cotton Disease Council indicate losses of over 109,000 bales (227 kg or 500 lb) in the United States in 2004 (12)

The declining quality of late-Holocene ombrotrophic communities and the loss of Sphagnum austinii (Sull. ex Aust.) on raised bogs in Wales

The modern floristic composition of the principal raised bogs of Wales is significantly altered compared with their histories of development from the early to mid Holocene. This paper uses pollen and plant macrofossil records from two raised bogs together with previously published data from a further two sites to explore the key factors contributing to the present condition of Welsh ombrotrophic plant communities. Results show Betula and Molinia invasion is a recent feature of bog development in Wales. Previous Holocene 'dry-phases' were characterized by Ericaceae and Pinus establishment, supporting recent experimental evidence that Betula and Molinia encroachment is primarily a response to nitrogen (N) loading rather than desiccation on intact bogs. Several of the bogs featured in this study also show severe signs of structural damage, not only from peat cutting but, in the case of Cors Caron, from channel processes in the adjacent River Teifi. Radiocarbon dating and inter-site comparisons of peat accumulation rates show that Rhos Goch Common in particular has been heavily impacted by peripheral peat cutting, leading to dewatering, significant subsidence of its peat dome and the spread of hummock and high dry ridge communities. Finally, the decline and local extinction of Sphagnum austinii in bogs across Europe represents one of the most significant changes in ombrotrophic community composition in the late Holocene. Co-registered pollen and macrofossil evidence from Cors Caron demonstrates that increases in landuse intensity over the last 2000 years are temporally associated with reductions in the abundance of S. austinii and ultimately its local disappearance from the palaeoecological record

Biologia e ecologia de Anthodioctes moratoi Urban (Hymenoptera, Megachilidae, Anthidiini) em matas contínuas e fragmentos na Amazônia Central, Brasil Biology and ecology of Anthodioctes moratoi Urban (Hymenoptera, Megachilidae, Anthidiini) in continuous forests and forest fragments in Central Amazonia, Brazil

<abstract language="eng">Anthodioctes moratoi Urban, 1999 was described based on specimens collected in tlhe state of Amazonas during a study of the ecology of trap-nesting bees and wasps. Sampling was done between 1988 and 1990 north of Manaus, in areas of the "Forest Fragment Biological Dynamics Project". Wooden trap-nests were set in different heights inside continuous forests, forest fragments of different sizes, natural gaps inside continuous forest, and in cleared areas between forest fragments. A total of 61 nests were collected from which 33 males and 46 females emerged. The majority of nests was collected in continuous forests, at 15 m height, in holes 4.8 mm in diameter. No nest was collected in cleared areas. There was no correlation, neither between number of nests and monthly precipitation, nor between the monthly number of nests constructed in the two consecutive years. No nest was constructed between January and June 1989. Overall, this coincided with the period of least activity of other trap-nesting bees in the studied areas. The nests consisted of a linear series of brood cells with walls made of resinous material mixed with small wood chips. The average length of the provisioned cell was 13,4 mm. Half of this length was occupied by a pollen mass. The number of provisioned cells varied between two and nine. In 52% of the nests there was brood mortality in at least one cell. The phorid fly Phalacrotophora (Omapanta) sp. was the only nest associate, emerged, from just one cell