Hot and bothered – Where's your seed been stored?

Endophyte doesn’t just get heat stressed; it dies. And unless the seed is checked near the time you sow it, you won’t know the endophyte is gone until your new pasture is attacked by insect pests and fails to thrive. Jake Gardner says the new research proves even moderate heat and humidity is enough to kill endophyte surprisingly quickly.

In fact, a recent study found endophyte in seed stored at ambient temperature – 15 - 25°C, with 65% relative humidity – started dying after just three months. “In many areas of the North Island, those conditions would not be unusual in the lead up to autumn sowing, which is also a time where we see others storing seed at ambient temperatures,” he says. Compounding this risk is the fact that most ryegrass seed sold for autumn renewal is at least 12 months old, because the window between harvest and sowing is too brief to process it all.

That’s why Barenbrug has invested in a 400 tonne Waikato cool store, purpose-built to keep endophytic ryegrass seed safe until as close to sowing as possible. After all the work that goes into growing, harvesting and processing high quality seed, Jake says, the company was not prepared to compromise on stewardship for this final step. The new site complements Barenbrug’s existing cool storage in the South Island, where most seed is grown. “We believe our infrastructure is second to none when it comes to ensuring our seed arrives in perfect condition for sowing,” Jake says.

1 – Thant, Hampton, Rolston and Lawrie (2025). Seed packaging bag types – impact on endophyte viability and seed quality in perennial ryegrass during storage.