The ASTI's ban on its 17,000 members doing in-service training looks set to play havoc with two Leaving Certificate subjects in September.
The Department of Education has said it intends to introduce new syllabi in biology and home economics in September, but the ASTI ban looks like causing serious difficulties with this plan.
Yesterday Folens Publishing said it was not prepared to publish textbooks to accompany the new syllabi because of the commercial risk that they might not be relevant if teachers were not trained in the new syllabi.
The company is concerned about the cost of a large print run if the textbooks are not then used in the classroom.
If companies refuse to publish the material the Department's chances of introducing the changes will be severely hampered.
The problems caused by the ASTI ban were compounded by calls by the Joint Managerial Body (JMB) to postpone introducing the new syllabi for another year.
The JMB's general secretary, Mr George O,Callaghan, said schools needed "a breathing space" before they were introduced.
"It would be preferable if the timetable was put back a year seeing as teachers have not been properly trained," he said. The JMB represents hundreds of voluntary secondary schools.
The numbers taking home economics and biology are relatively high by Leaving Cert standards.
While the figures fluctuate from year to year, about 20,000 students normally take home economics, with about 30,000 taking biology.
The TUI has not instructed its members to stop going on in-service courses, but its agreement would not be enough to remove the commercial risk to publishers.
Meanwhile Mr O'Callaghan issued a statement saying the final term this year was likely to be very tough for schools.
"Schools face enhanced difficulties this term in attempting to balance the operation of the contingency arrangements and the management of the oral and practical examinations," he said.
"The workload of principals and deputy principals in our schools has increased enormously as a result of the operation of the contingency arrangements."