A campaign aimed at reducing the pressures on primaries says the decision is its first success.
Ms Morris admitted that more interference would be counter-productive in a letter to MPs who back the Time to Teach drive - led by literacy expert Sue Palmer.
She said: "We fully agree that further radical innovation and new programmes are not the key to further improvements.
"Rather, we are committed to embedding the existing strategy in every primary school across the country. We recognise that the introduction of the literacy and numeracy strategies asked a great deal of teachers and they deserve much credit for the major improvements that we have seen in the standards that pupils are achieving."
Ms Palmer said: "I welcome the Secretary of State's recognition that if she bombards teachers they do not have time to do their job.
"The Government needs to realise that tests and targets mean teachers are too busy coaching to teach properly."
Ms Morris's letter will come as a relief to primary staff who have been coping with wide-ranging reforms for more than a decade.
In the mid-90s, Sir Ron Dearing, said primary teachers were exhausted and negotiated a five-year moratorium on change. However, Labour's 1997 victory led to nationally-prescribed strategies to improve the teaching of the 3Rs.
The Government's focus will shift to secondary education with the overhaul of key stage 3 lessons and 14 to 19 education.
However, key stage 2 targets for 2004 will stand. By then, 85 per cent of pupils should reach the expected level in English and maths and 35 per cent of pupils should reach the higher level 5.