The value of corn and other crops grown in Hawaii to produce new seed varieties for farmers has fallen to a 13-year low, according to a government estimate published Thursday.

Estimated spending by Hawaii’s seed crop industry declined 13% to roughly $106 million in the most recent season, wrapping up this month, the U.S. Department of Agriculture reported.

That’s down from $122 million in the prior season and a record $242 million in 2012.

Since 2012 Hawaii’s seed crop industry has been shrinking with the exception of two slight increases, in large part because of maturing research, industry consolidation and corn price decreases.

The last time the value of the industry was lower than this recent season was 2006 at $77 million.

Seed producers, mainly giant agribusiness companies, have had a presence in Hawaii since the 1960s to take advantage of the climate, in which corn can be raised to maturity three or four times in a year compared with only once a year on the mainland.

The industry in Hawaii began to boom around 2005, and a year later eclipsed sugar cane and pineapple as the state’s biggest crop by value.

Unlike food crops, however, the value of seeds is measured by the cost of production instead of crop sales because the seeds aren’t sold. Seed producers use what they grow for research and to start mass reproduction on big farms outside Hawaii.

Bennette Misalucha, director of the Hawaii Crop Improvement Association representing seed companies, said in a statement that cost efficiencies have allowed companies to produce more seed at lower costs, and that this also has contributed to the declining measure of industry value.

Corn accounted for 97%, or $102 million, of the industry value in the recent season. Other seed crops in Hawaii have included soybeans, wheat, sunflowers, rice, rapeseed and sorghum.

Many local agriculture leaders view the seed business as a good force that has kept workers employed and farmland productive amid declines in pineapple farming and the end of large-scale sugar cane production. Yet many environmentalists and natural food proponents detest the industry because much of the work involves genetic engineering. Such concerns have led to litigation as well as state and county initiatives to restrict or ban work with genetically modified organisms.

The USDA’s report provides a preliminary estimate based on farm surveys conducted with state Department of Agriculture assistance, and could be revised.

One big revision was made to last year’s report, which initially said there was a surge in seeds shipped out of the state. Last year’s report said shipments soared 67% to a record 12.7 million pounds. But the revision reported Thursday said last year’s shipments actually fell 30% to 5.3 million pounds.

In the most recent season, estimated seed shipments declined an additional 9% to 4.8 million pounds.

The season for growing seeds in Hawaii is year-round, though USDA said the main season runs from November to June.

Since 2017 four companies have made up Hawaii’s seed industry: Beck’s, DowDuPont, Hartung Brothers Inc. and Bayer. These seed producers used 2,530 acres of land in the recent season, down from 3,030 acres a year earlier and a peak of 6,910 acres in 2012.