Fungal Colonization of Alfalfa Stubble Following Harvest

Two-year-old stands of alfalfa cultivars Saranac and Vernal, planted in Central Iowa, were sampled 0, 15, and 30 days after the first harvest in 1995 to identify fungi colonizing the stubble left after harvest and evaluate the role of harvest-induced wounds as infection sites for potential crown-rotting fungi. Analysis of variance was conducted to determine if sampling date and cultivar significantly affected incidence of the fungi. All stems were infected with at least one fungal species at every sampling dare. The fungal genera most frequently isolated were Alternaria, Colletotrichum, Fusarium, Phoma, and Rhizoctonia. Fusarium acuminatum was the most frequently isolated Fusarium species. Other species included F. sambucinum and F. sporotrichioides, but not F. oxysporum or F. solani. Incidence of Colletotrichum decreased significantly over time, while the incidence of Alternaria increased significantly. Cultivar had a significant effect on Colletotrichum incidence, but not on incidence of other fungi. Potential crown rot pathogens were present on the stems at harvest, and their incidence generally did not increase significantly over time. These results do not provide evidence that wounds made by harvest equipment were important infection sites. Potential crown-rotting fungi were present in the stems at harvest; senescence of stem tissue after harvest may be important in the movement of fungi into the crowns

The Effect of Nitrogen Fertiliser and Season on the \u3cem\u3ein Situ\u3c/em\u3e Degradability of Irish Perennial Ryegrass in Cattle

In light of increasing environmental and economic pressure on agriculture to utilise resources more efficiently, protein feeding and its effects are fundamentally important. As grazed grass is the predominant feed in Irish dairy and beef cattle production systems, it is necessary to establish protein values for different grass varieties and cultivars fed. It is also important to investigate the extent of ruminal nitrogen (N) degradability for these grasses since this characteristic greatly influences environmentally damaging urinary N excretion