Hi fellow horse owners and equine enthusiasts:
This certainly has been an unusual summer – weather wise. I want to alert you to a condition that your horses may experience due to the high humidity levels and continuous rainfall. I have been receiving a large number of emails asking about the cause of equine slobbers in horses. Equine slobbers is caused by a fungus called Rhizoctonia that grows on clover and alfalfa. The fungus produces a toxin called slaframine. While the toxin normally only causes horses to drool, when rhizoctonia levels are high – like they have been in some pastures this summer – it can cause more serious effects such as increased urination, feed refusal, and difficulty breathing. Several farms have reported seeing these symptoms in horses grazing pastures with high concentrations of clover. The rhizoctonia can be seen growing on the undersides of the clover leaves. It looks like tiny brown tar colored spots. You may need to remove horses from pastures containing high levels of rhizoctonia if you are seeing any of the more serious side effects. If you have any questions, you can contact me at firstname.lastname@example.org.
Donna Foulk – PSU Equine Natural Resources Educator
This email was sent on behalf of the College of Agricultural Sciences, The Pennsylvania State University, Ag Administration Building, University Park, PA 16802.
A fact sheet accompanied this email with several strategies listed to reduce drooling caused by Rhizoctonia:
• Remove horses from infected pastures
• Mow pastures until the brown fungal spots are no longer present on the leaves
• Increase the concentration of grass by over seeding pastures and applying nitrogen fertilizer in spring and fall.
• Rest and rotate pastures to allow the grass to remain tall and competitive with the clover.
• Broad leaf herbicides, labeled for pasture use, can be used to remove existing clover plants from pastures.