David Woods was looking at the early Irish chronicles and he noticed something very odd. There are clusters of entries recording large mast crops. Mast? In Ireland, that would be mostly acorns.. In these sparse annals that normally only record battles, deaths, and other major events, why record large acorn falls? The only typical use for mast / acorns is to feed pigs. But the chronicles ignore pigs. To make it even odder, there are no other entries in the Irish chronicles for any other specific crop. There are only a couple references to bread failure, but as Woods notes, this is still not a reference to a specific crop. Further, there is no antique precedent for recording mast crops. Woods notes that none of the antique chroniclers, most of whom did record natural disasters and bad omens (like a red moon or comet) recorded mast crops. So what is going on here?
Knowing that chroniclers decided what type of thing to record in the chronicles by reading earlier entries, Woods focused in on the earliest entries of large mast falls. The earliest entry in the Annals of Ulster comes in 576: “Scintilla lepre 7 habundantia nucum inaudita” (“a spark of leprosy and an unheard of abundance of nuts”). The conjunction of some type of skin illness with the large nut fall suggests that the chronicler may have misunderstood his source. It is likely that this early section of the Annals of Ulster was constructed retrospectively from older records. Woods (p. 498) suggests that “this entry had originally described an occurrence of a magna pestis glandularia in addition to a scintilla lepre, but the editor or copyist misunderstood the term glandularia.”
The Latin term glandularius is the root of our word for gland; etymologically, glandula means ‘little nuts’ because this is what they felt like when palpated. There is at least one other example of a plague record using glandulara as a descriptor. In c. 660 the Burgundian ‘Chronicle of Fredegar’ describes the 599 plague of Marseilles as a cladis glanduaria.
For Woods hypothesis to work, the copyist/chronicler must have mistaken pestis to mean a general calamity rather than a specific disease (or any disease for that matter). Later longer entries in the annals suggest that large mast crops could indeed be problematic by blocking streams and presumably causing flooding. The record of an “abundance of mast” in 672 fits with Woods theory that this “mistaken paraphrase” occurred when the ‘Iona Chronicle’, the parent of the Annals of Ulster, was compiled from older records in the 670s. A recent large mast crop could have prompted the chronicler’s paraphrase mistaking glandular plague with a glut of acorns.
When the plague first swept across Europe it took four years to arrive in Ireland. Plague was first reported at Pelusium in 541, Constantinople in 542 and reached Ireland in 545 (according to the Annals of Ulster). If we have a probable plague entry in Ireland we should find other plague records in Europe or the Mediterranean, and so we do. Bishop Maurius of Avenches dates an outbreak of “glandular” plague to 571. An outbreak was also recorded in Constantinople by Spanish visitor John of Biclaro in 573. The Irish record in 576 fits in. Given how sparse sixth century records are, this is about all we should expect for a wave of plague moving across Europe in the 570s.
David Woods (2003). Acorns, the Plague, and the ‘Iona Chronicle’ Peritia (17-18), 495-502.