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May 9, 2002

Report from Jimmy Henning, Extension Forage Specialist
Department of Agronomy
University of Kentucky College of Agriculture

Twelve horse farms and one hay farm are being monitored for several soil, pasture and environmental parameters thought to be related to the MRLS outbreak of 2001. Forage samples are analyzed for fungal mycotoxins, alkaloids associated with tall fescue, cyanide and minerals. Soil samples are checked for populations of yeasts and molds.

As of May 8, all sentinel farms have had 5 or 6 cycles of sampling completed. MRLS symptoms have been noted on some monitoring farms and preliminary followups are consistent with exposure to eastern tent caterpillars or proximity to wild cherry trees.

Sample results are summarized below:

Fungal mycotoxins: 174 samples have been submitted with 174 results returned. All data are below detectable limits or very low. Small amounts of Fusarium mycotoxins including zearalenone (500 ppb), T-2 toxin and deoxynivalenol (DON) have been found by ELISA techniques in some samples. In some cases, DON has been detected in fields associated with MRLS in 2002 and from pasture samples taken in proximity to wild cherry trees. However, levels of DON detected in these fields are low. These fields will be followed closely to permit more informative interpretation of the data.

Alkaloids associated with tall fescue: 442 samples submitted, 320 results returned. Loline and ergot-type alkaloid values are rising. In all but a few cases, alkaloid levels are low and are not a concern. In a few fields, levels of ergovaline in tall fescue are high enough (>600 ppb) to warrant concern if this tall fescue formed the primary diet for mares in the last 60 days of gestation.

Cyanide associated with white clover: 170 submitted, 138 returned. Levels vary by field and are within ranges reported for white clover. Present values are higher than early spring.

Forage mineral content (including nitrate): 167 submitted, 139 returned. All samples are within normal ranges.

Soil microbial counts: 267 samples submitted, 230 returned. Counts for yeasts and molds are variable but within a normally expected range. Total populations are similar to values reported earlier but are rising in some fields. Fungi from the Aspergillus, Fusarium and Penicillium genera have been found in quantity on a few of the late April samples. Strains from these genera have been known to produce toxins. However, all mycotoxin values in forage are below detectable limits or very low.

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