The Environment Secretary acknowledged that taking a long term approach to Chalara fraxinea was now the most effective strategy.
The two new Essex sites confirmed with the chalara fungus are in the Frinton and South Woodham Ferrers areas.
The Forestry Commission announced on Monday that the tree disease chalara had been found in woodland in Kent and Essex.
The deadly chalara fungus is creeping its way across Britain and is threatening to wipe out ash trees it infects.
Chlara dieback of ash is caused by a fungus called Chalara fraxinea.
More than 150 Forestry Commission staff, and a Scottish government team, are working round the clock to look for signs of Chalara ash dieback.
The Chalara fraxinea fungus, which causes Chalara dieback - also known as ash dieback - has already killed 90% of ash trees in Denmark.
Chalara ash dieback was found in July in five young trees out of a batch of 100 supplied to Plants Ltd in Woodcock Lane, Chobham.
Chalara dieback of ash is caused by the Chalara fraxinea fungus.
Existing stocks of ash will be bought and planted in the East and South East of England where most of the Chalara outbreaks have taken place.
Prof Kowalski named the new fungal species Chalara fraxinea - but as the disease spread across the continent, he realised that something was not quite right.
Dieback, caused by the Chalara fraxinea fungus, was first recorded in eastern Europe in 1992 and spread over two decades to infect most of the continent.
According to the Forestry Commission, outbreaks of the disease, caused by the fungus Chalara fraxinea, have been found at 427 sites in across Great Britain and Northern Ireland.
Scientists say the infection in native trees has been caused by a fungus Chalara fraxinea, which is believed to have been carried on the wind from mainland Europe.
Chalara dieback of ash, caused by the fungus chalara fraxinea, was identified at the new Welsh sites during a "trace forward" inspection of young trees sourced from known infected nurseries.
There is now more and more data emerging to show that Chalara fraxinea is not a European native species and could have come from Asia - including a recent paper in the journal Mycotaxon.
Researchers said the affected trees in woodlands in Norfolk and Suffolk were likely to have become infected as a result of coming into contact with Chalara fraxinea spores that had been blown over from mainland Europe.
The disease - caused by the fungus Chalara fraxinea - has also been found in the wider environment in the south east of England and the east side of Scotland since it was first recorded in Britain in early 2012.
Dr John Morgan, head of the Forestry Commission's plant health service, said the work would help shed light on "the history and nature of the introduction of new pests like Chalara, and in helping to understand how we tackle the disease that's arrived and to understand what the risk of spreading is".
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