URBANDALE, Iowa — Gov. Terry Branstad said Thursday he is concerned current state revenue growth may not be strong enough to support a statewide summer reading initiative designed to make sure third graders meet proficiency standards that are a key educational building block.

State lawmakers grudgingly agreed last session to move back by one year— from spring 2017 to 2018 — the implementation of a new statewide literacy law after the governor did not include funding for the program in his two-year state budget plan and eroding state tax collections last spring further squeezed the funding priority list.

Now, as Branstad and legislators look to their fiscal 2018 budget prospects, the governor said finances are "stressed" and revenue growth is being hampered by farm prices below production costs and bird flu after-effects. That could spell more trouble for school districts hoping for state money to accompany a summer reading requirement.

"That will really depend upon the state's financial resources," Branstad said.

He pointed to the December meeting of the state Revenue Estimating Conference as a key determinant in how much tax money will be available to budget for next fiscal year or for a supplemental appropriation early in the session that might get the early literacy program back on track for next summer. The effort is designed to identify struggling readers starting in kindergarten and require schools to provide intensive assistance.

"We've been going through a challenging time," Branstad told reporters after meeting with teachers and administrators at an Urbandale elementary school and touring their successful reading program. "It does depend on what the budget situation is going to be like. It might be possible if all of a sudden revenues turn around and exceed expectations that we could pass early in the session a supplemental and move it up again. But that doesn't look very likely if you just look at what's happened to date. I think we have to be realistic about the financial circumstance.

"Due to the financial conditions that the state is facing, it may be a year later than we had hoped. But I'm very optimistic that we're going to be able to continue to make progress."

Evidence of that progress could come soon when the state Department of Education releases statewide test results in reading and math proficiency, the governor said.

"I understand that preliminary statewide results show the same share of third-grade reading proficiency last year to be pretty comparable with the year before at about 76.1 percent," he said.

Branstad also said he hopes to get results this fall from a pilot project this past summer that studied best practices. The $1.9 million research, conducted by the Iowa Reading Research Center under the auspices of the Iowa Department of Education, encompassed 120 schools in 44 school districts.

On Thursday, Olmsted Elementary School Principal Elyse Brimeyer said her school has seen positive results from a collaborative, responsive classroom approach that focuses on academic, social and emotional development that is wrapped around the students' individual needs.

Branstad said he was impressed and encouraged by what he saw but added that another key component is proactive parents who are reading to their children from an early age and then working with teachers to guide literacy development.

"What I'm encouraged about is that school districts are not waiting," he said. "Many school districts are already moving forward, and they already have programs."