You may want to remember that the seeds of some fruit is poisonous, even though the fruit itself isn't. I didn't know about crabapple (I know there are many different varieties), but I found that this lists the chewed seeds of crabapple as poisonous:
http://hsc.unm.edu/Pharmacy/poison/z...20Plants.shtml
This states that crabapple seeds - Major Toxicity: These plants may cause serious illness or death. If ingested, immediately call the Poison Control Center or your doctor.
http://www.plantsciences.ucdavis.edu...nt/Tox-SCI.htm