Farmers unlock the power of endophytes

The perennial ryegrass on which much of New Zealand’s pastoral agriculture depends uses a fungus that grows within the plant, known as an “endophyte”, to protect itself from insect pests. However it can also have implications for animal health.

AgResearch scientists discovered a novel endophyte (AR37) which provides ryegrass with the insect protection advantages and plant persistence delivered by standard endophytes but has few adverse effects on animal health.

Since its first release in 2006, AR37 has been included in 11 ryegrass cultivars and its uptake by New Zealand farmers has been very strong.
Although it has been used in many locations throughout New Zealand, AR37 is especially valuable in areas affected by black beetle, mainly the North Island from the Central Plateau northwards, for which an assumed 3% annual re-grassing rate for dairy pastures would lead to 21,500 ha per year being re-grassed.

With an estimated benefit of 84 kg of milksolids per hectare more milk production, at a milk price of $6/kgMS, the cumulative net benefit to the dairy sector of re-grassing that area each year with AR37-containing ryegrass up to 2012, after subtracting the share of re-grassing costs attributable to AR37, is estimated to have been about $125 million.

Howard Lilly, who farms in Karaka says that their stock are doing well on pasture with the AR37 endophyte.

“The beef stock we had on it were coming off at 640kg on average after 15 months and the dairy heifers put on great condition,” he says.
“We needed the AR37 for persistence against black beetle and we wanted a modern high performance grass. We have had two years out of this pasture now and we are very happy with it.”

The AR37 endophyte was identified along with a number of other endophyte strains during the 1980s and early 1990s. Subsequent research found that AR37 did not produce the alkaloid compounds that were toxic to animals but it did produce an unique compound that conferred a wide range of tolerance to insect pests, including Argentine stem weevil, black beetle, root aphid, pasture mealy bug and porina.

AR37 also provided increased ryegrass tiller numbers, root mass and depth, persistence and higher yields at critical times of the year.