Crickets go off the grass

Ever-ravenous crickets simply cannot stomach a new endophyte developed to protect grasses from them.

Farmers whose pastures are severely affected by black field crickets will welcome the news that a new endophyte protects host grasses from the pest.

After 15 years of research and development by Cropmark Seeds, the GrubOUT U2 endophyte was launched last autumn and is available in the company's ready-to-sow Barrier Combo permanent pasture mix.

Cropmark chief executive Glen Jarvis says research conducted on its behalf had shown crickets seemed particularly sensitive to loline alkaloids produced by the GrubOUT U2 endophyte in Barrier Combo.

"The research has clearly shown that crickets won't eat grass containing lolines," Jarvis says.

"There is a very strong feeding deterrence effect. This is a valuable trait for a pasture to have, given the fact that crickets can be a significant pasture pest in many parts of the country."

Black field crickets are found throughout the North Island and milder parts of the South Island, but they are generally only of serious economic importance in northern areas - Northland especially.

Damage to pastures can be considerable, affecting establishing seedlings and established pastures, resulting in reduced pasture production and even plant death.

AgResearch's website, Pestweb, says two crickets a square metre over 1ha will eat as much as a sheep.

In plague seasons as many as 20 to 40 crickets/m2 frequently occur and can cause losses of 30kg DM/ha/day.

In dairy pasture terms, an average density of 25 crickets/m2 can be responsible for 2000kg DM/ha/yr lost production.

The use of Barrier Combo pasture, which contains the endophyte, will provide a cost-effective, animal-safe tool against the damage crickets caused, resulting in potentially greater long-term pasture yield and persistence.

But it is not only crickets the endophyte affects.

It has already been reported that the endophyte, which is the only one to operate above and below ground, protects host grasses from grass grub, black beetle adults and larvae, porina caterpillar and Argentine stem weevil.

"Results in the field have been spectacular. In trials we have seen all other ryegrass/endophyte combinations wiped out by heavy infestations of grass grub and black beetle, whereas grasses containing the GrubOUT U2 have been unaffected," says Jarvis.

"The other exciting aspect is that the endophyte is safe to sheep, cattle and deer and does not cause grass staggers or heat stress.

"It has not yet been tested on horses or alpacas, and so Cropmark is stopping short of recommending it for them yet.

"While some of New Zealand's most serious insect pests don't like eating Barrier Combo because of the GrubOUT U2 endophyte it contains, livestock do.

"Experience throughout the country has shown that stock find it extremely palatable and will graze it preferentially over other ryegrass/endophyte combinations," Jarvis says.

For best establishment, the Barrier Combo pasture mix (which comes with medium and large-leafed white clovers) should be sown at a rate of 25kg/ha or more to a depth of no more than 1 to 2cm, into a well worked, firm seed bed when soil temperatures are 12C or more.

Sowing into existing pastures is not recommended because it dilutes the mix's effectiveness.

The seed is available through Ravensdown, Farmlands and other seed retailers.