Mewn meithrinfa yn ne Lloegr ym mis Chwefror 2012 y gwelwyd yr achos cyntaf o’r clefyd ym Mhrydain.  Ers hynny, mae wedi’i ddarganfod mewn coed ifanc mewn sawl meithrinfa ac erbyn hyn, fe’i cafwyd mewn mwy na 100 o feithrinfeydd a choedlannau, yn bennaf yn nwyrain Lloegr.  Credir i’r clefyd gyrraedd Prydain trwy blanhigion wedi’u mewnforio a chan sborau a chwythwyd gan y gwynt dros y môr i ddwyrain Lloegr o Ewrop.
The disease was first intercepted at a nursery in southern England in February 2012. Since then, it has been found to be in young ash trees plants in several plant nurseries and is now known to be in over 100 plant nursery and woodland sites, mainly in eastern England. It is thought to have reached the UK through the importation of infected plants and via its spores being blown into eastern England from Europe.