Seed testing is always important, but this year will really show its value, says Barry Little of 20/20 Seed Labs.
“Disease levels can be as high as 10 times normal this year,” says Little. “Around 20 per cent of seed we’re testing just isn’t suitable for seeding because of disease.”
Little says seed testing should be one of the normal crop inputs you include in the budget as you pencil out crops.
“It is a cost,” he says. “But the return on the investment is as good as on any other crop input.”
He recommends testing for vigour, thousand-kernel weight, and disease screening – which he calls the three critical seed tests – as well as germination.
“Depending on the crop, there could be any or all of six to 10 pathogens on the seed,” he says. “It’s important to know whether your seed is infected and with what. Then, you need to check which seed treatments control or just suppress that disease.”
This year, you really need control, rather than just suppression, and in some cases, you may need a different source of seed.
“Before this, we thought three per cent asochyta was a high level of infection. But this year, we’re seeing 30 per cent. Not even the best seed treatment will control that level of disease.”
Seed disease levels and germination can affect each other, says Little. Pulses may have good germination, despite high disease levels, but that’s not always the case with cereals.
“In a germ test, we may classify a seed as dead, due to disease,” he says. “Using a seed treatment that kills the pathogen might allow the seed to germinate. But, if the problem was frost or some other abiotic stress, nothing brings that dead seed back to life.
“So you need to know the issues with seed. Although there’s no guarantee, you may be able to revive 10 or 20 per cent of cereal seed with low germ because of fungal issues.”
Little always recommends using a seeding rate calculator, but especially this year. You can use seedling vigour to predict seedling mortality – for example, seed with an 80 per cent vigour score, put in 20 per cent – the difference between germination and vigour – to estimate seedling mortality.
Little has one recommendation that isn’t directly related to seed: Rotate everything. A disease that’s seed-borne can also be soil-borne, he says.
“And that can amplify any problem. Even with clean seed, soil-borne disease can be an issue, especially in pulses , which are more susceptible to disease than cereals. That’s the only blanket recommendation I make.”