Feeding your horse poor quality, hard-to-digest hay has been implicated in equine impaction colics but other plants can cause blockages, too.
Mesquite
Mesquite (Prosopis glandulosa beans are very high in sugar and starch and may cause obstructions of the small and large intestine.
Persimmons
Ripe persimmons (Diospyros virginaia) may contribute to impaction colics. The plant fibers form a hardened mass in the digestive tract of your horse that may disrupt or block the small or large intestine. Pain and discomfort may not appear until several months after consumption.
Hawthorne
Cockspur hawthorn (Crataegus crusgalli) fruits may cause equine impaction colic or diarrhea.