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The maize endophyte Acremonium zeae is antagonistic to kernel rotting and mycotoxin producing fungi Aspergillus flavus and Fusarium verticillioides in cultural tests for antagonism, and interferes with A. flavus infection and aflatoxin contamination of preharvest maize kernels. Chemical studies of an organic extract from maize kernel fermentations of Acremonium zeae (NRRL 13540), which displayed significant antifungal activity against Aspergillus flavus and F. verticillioides, revealed that the metabolites accounting for this activity were two newly reported antibiotics pyrrocidines A and B. Pyrrocidines were detected in fermentation extracts for 12 NRRL cultures of Acremonium zeae isolated from maize kernels harvested in Illinois (4/4 cultures), North Carolina (5/5), Georgia (1/2) and unrecorded locations within the USA (2/2). Pyrrocidine B was detected by LCMSMS in whole symptomatic maize kernels removed at harvest from ears of a commercial hybrid that were wound-inoculated in the milk stage with A. zeae (NRRL 13540) or (NRRL 13541). The pyrrocidines were first reported from the fermentation broth of an unidentified filamentous fungus LL-Cyan426, isolated from a mixed Douglas Fir hardwood forest on Crane Island Preserve, Washington, in 1993. Pyrrocidine A exhibited potent activity against most Gram-positive bacteria, including drug-resistant strains, and was also active against the yeast Candida albicans. In an evaluation of cultural antagonism between 13 isolates of A. zeae in pairings with A. flavus (NRRL 6541) and F. verticillioides (NRRL 25457), A. zeae (NRRL 6415) and (NRRL 34556) produced the strongest reaction, inhibiting both organisms at a distance while continuing to grow through the resulting clear zone at an unchanged rate. Maximum colony diameters for A. zeae (NRRL 6415) and (NRRL 13540), on potato dextrose agar after 14 d, were attained within the range of 25-30 degrees C, with less growth recorded at 15 degrees and 37.5 degrees and no growth at 5 degrees. Potential interactions between A. zeae and other maize endophytes are considered and the significance of these interactions relative to the aflatoxin and fumonisin contamination of preharvest maize is presented. This is the first report of natural products from Acremonium zeae.

Tall fescue (Festuca arundinacea, Shreb.) is the predominant cool-season, perennial grass in the eastern half of the United States, and the majority is infected with the endemic endophyte (E+) Neotyphodium coenophialum, resulting in millions of dollars in revenues lost to the beef industry. Endophyte-free (E-) tall fescue was initially tapped as a "silver bullet" for the solution to fescue toxicosis, but drought intolerance and overgrazing have often resulted in nearly complete stand losses in 3 to 4 yr. Recently, the discovery of new endophytes that do not produce ergot alkaloids has resulted in the development of novel-endophyte-infected (NE+), stress-tolerant tall fescue plants. These NE+ tall fescue plants combine the plant persistence advantages of E+ (infected) tall fescue with the animal performance advantages of an E- tall fescue. Controlled studies from several locations in the southern United States have shown that the three commercially available cultivars of NE+ tall fescue persist as well as E+ tall fescues. Stocker cattle performance trials from five states have shown that the ADG in cattle grazing NE+ tall fescue was 47% greater than in cattle grazing E+ tall fescue and that cattle show no signs of fescue toxicosis. Economic evaluations of establishment cost and improved animal performance indicate that a stand of NE+ tall fescue would require 7 yr to pay off and begin to return profit to the enterprise if calves grazing E+ pasture are not discounted in price for fescue toxicosis at marketing. Average discounts at marketing for cattle showing signs of fescue toxicosis are $7.49/45.4 kg of BW. Assuming E+ cattle are discounted at sale and the quality of cattle is not decreased by the use of NE+ tall fescue, a stand of NE+ tall fescue would require 3 yr to pay the expense of establishment and begin to return profit to the enterprise.