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"Poisonous" does not mean deadly. Some manifestations of toxicity are subtle. The dose, as always, determines if a plant is safe source of nutrients or a toxic hazard.

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BRIEF: I need some information on Fiddleneck...

I need some help locating information on the plant, fiddleneck. We just purchased a home with acreage for our horses in Northern California. The local Veterinarian stopped by our home and told us our pasture was full of fiddleneck and it could be fatal to our horses. Using the internet, I was able to establish that the seeds were actually toxic; but when does the plant go to seed and how do we get rid of it?  Can we just mow the flower tops down? We have been pulling it up by hand as quickly as possible, but the horses are eating it. We nearly lost our 6 month old filly, 2 years ago to starthistle poisoning. We hand fed her a mush mixture of ground oats and alfalfa pellets for 3 months until she was able to find another way to eat on her own.


It could be that your horses may not get enough to hurt them, but you are wise to be concerned and take steps to get them off the fiddleneck. Fiddleneck (Amsinckia intermedia) contains some potent pyrrolizidine alkaloids that can cause severe liver damage. It may take a quite some time to kill or injure a horse, or it can happen quickly, depending on the dose. Of course this is the time of year it is a big problem because very often on disturbed sites (orchards, roadsides, fields disced last year, etc.) it can be the dominant plant in March-April. The whole plant is toxic, so you need to worry about more than the seeds. For controlling fiddleneck, you should ask a weed specialist at your Cooperative Extension office. I would guess mowing would help and seeding to desirable species can't hurt. Will this area be irrigated? If so, you can favor more desirable species very easily. Once irrigated perennial species are established, they can outcompete fiddleneck (and star thistle, etc.), but you need to watch the edges of the fields where the water doesn't reach. Fiddleneck finds its way into first cutting hay in California, since it volunteers and comes up with the late Winter, early Spring rains and matures along with the alfalfa. It is usually found around the edges of a hay field, especially in spots where the sprinklers don't quite reach. We all know that jaundice (vets call it icterus lately, but it is still a yellowing of the eyes and normally light membranes) is a symptom of liver damage. What you may not know that in the case of fiddleneck (or senecio or comfrey) poisoning, the first symptoms you see may be head pressing and walking around aimlessly (because of failure of the liver to detoxify ammonia) or a severe photosensitive skin problem (due to failure to conpletely process chlorophyll, usually on white horses or white parts of paints). I am very impressed that you were able to nurse a horse back to health after it suffered brain damage from yellow star thistle. I did not know that could be done. You must be a great healer.