Forestry Commission head of analysts Roger Coppock told MPs: "We did start work on a pest risk analysis, but we were already dealing with other diseases and pests and the number of plant pathologists is very small.
Defra chief scientist Prof Ian Boyd told the committee: "We need more university courses to produce more people trained in plant pathology."
The Forestry Commission recommended in July 2011 that ash trees should only be imported from areas free of ash dieback, but an import ban was only imposed in October 2012. At least 136 of the 291 infected sites now identified in the UK resulted from imported trees.
Boyd said how much ash firewood is imported is unknown, prompting commitee chair Anne McIntosh to state: "It is quite staggering we don't have this information."
Food, Environment and Research Agency chief plant health officer Martin Ward said: "The regime is not working as well as it should, but a more precautionary regime is in the offing."
Boyd said developing strains of ash trees that are naturally resistant to Chalara "will take a decade or more before this has an impact. Even if we start to propagate now, even after a decade an ash tree is not very large."