16/07/2026
To continue from the previous post re grassland.
The harbouring of diseases.
Yes, you are completely right. (Thankyou Al’)
Leaving an overgrown paddock to rot over winter creates a perfect storm for pasture diseases, fungal spores, and bacteria.When tall, dead grass collapses into a wet mat on the soil surface, it forms a humid microclimate with zero air circulation. This environment harbors several specific pathogens that threaten both the pasture and the horses.
1. Grass Rust (Puccinia / Uromyces Fungi)What happens: Rust thrives in late summer and autumn when dews are heavy and grass is weak or under-managed. It appears as dusty, bright orange or yellow pustules on the grass leaves.
The winter transition:
In late autumn, these fungi switch to producing black, cold-hardy overwintering spores that live directly in the dead thatch and soil.The impact: While rust itself is not directly toxic to horses, it destroys the palatability of the grass, ruins turf density, and ensures the paddock will be heavily infected again the following spring.
2. Mold, Mildew, and Mycotoxins
What happens: As the tall stalks die and damp winter conditions set in, the grass rots instead of curing like properly baled hay. White, grey, or pink molds develop throughout the thick mat of dead material.
The impact on horses: When horses put their noses down into the grass to search for the sweet regrowth at the base, they inhale millions of these mold spores. This is a prime trigger for Equine Asthma (historically called Heaves or Recurrent Airway Obstruction).
Mycotoxin risks: Certain molds living on decaying pasture litter release dangerous mycotoxins. When horses ingest these while scavenging, it can cause digestive upset, low-grade colic, or a suppressed immune system.
3. Microscopic Pasture Litter Hazards
Facial Eczema (Pithomyces chartarum): This fungus grows specifically on the dead, decaying grass litter at the base of overgrown pastures. It produces toxic spores that can cause liver damage and severe skin photosensitivity if ingested by livestock.
Soil-Borne Bacteria: When grass turns into a mushy, rotten mat, it traps soil moisture. Horses walking through it scrape their heels on the coarse, dead stalks, allowing soil bacteria to enter the skin. This leads to painful winter skin conditions like mud fever and rain scald.
Summary for Your Liveries
Overgrown, un-topped grass does not turn into clean, healthy "standing hay". Instead, it acts like a dirty, wet sponge that blankets the ground, suffocates next year's good grass roots, and creates a breeding ground for mold spores and fungal pathogens that damage equine lungs.
