Stick with high endophyte ryegrasses, farmers urged

Press, 7 February 1986, Page 14

Stick with high endophyte ryegrasses, farmers urged

Until a low endophyte ryegrass which resists Argentine stem weevil is identified or is engineered by plant breeders, fanners have been urged to stick with high endophyte cultivars, even in districts with a history of ryegrass staggers problems.

Following this philosophy, the Yates Company has releasd another high endophyte ryegrass cultivar, Yatsyn 1, to be marketed alongside Ellett. It is available in limited quantltes for sowing this autumn.

At field days on four sites in Canterbury recently, farmers were given the opportunity to see plots of Yatsyn 1 alongside Ellett, Nui and Ruanui. Other Yates ryegrasses under trial were also represented. The hot, harvesting weather unfortunately limited the number of farmers who took the chance to look. Because of promotion over a number of years most farmers will be aware of the story behind Ellett, the South Auckland ecotype (or locally adapted ryegrass) which was found to perform well in trials throughout New Zealand and marketed by Yates as an alternative to the, Grasslands cultivars. Ellett was a “find” which many plant breeders believe may have been the last of its type — the simple identification of a superior-pro-ducing ecotype already growing somewhere in New Zealand.

Although this work of selection and measurement still goes on at the Grasslands Division of the D.S.I.R. and several private research stations, the chances of finding a local ecotype which will outproduce and persist throughout the country — “shift and out-do” — must be getting smaller. At Yates’ Courtenay Research Station, near Darfield, the ryegrass researchers have 24,000

ecotypes as single plants, collected from around the country and especially from anywhere a superior grass was reported to be growing. These have been measured for years to identify the front-runners. Local ecotypes may well out-perform the nationally promoted varieties in their own regions. In Canterbury Mr Baden Powell has been a staunch advocate for “old pasture” ryegrass which has proved its persistence and production under rigorous conditions. There is a small trade in such seed, fostered by Mr Powell, and he is angry that the national certification scheme, which favours seed harvested from first-year ryegrass, works against the promotion of local ecotypes. These, by definition, have been down for years.

But the rye;

breeders are near unanimous that a local ecotype will not usually show the adaptability needed for national success. Ellett seems to have been an exception. The second tier of research effort involves crossbreeding the collected and known genotypes as a way of engineering a new superior ryegrass. A breeder at Courtenay, Mr Nick Cameron, has narrowed his 24,000 originals down to 5000 “elites" and has then combined many which have superior performance in some or all of the 34 characteristics he is interested in. The first few experimental cultivars with promise have then been trialled on 10 sites against Ellett and Nui, or both dryland and irrigated land. :rass Yatsyn 1 has consist-

ently cut more dry matter than Ellett by a few percentage points and both of them have produced more than low-endophyte Nui or high-endophyte Nui. Yatsyn’s superiority over Ellett is strongest in autumn when its recovery from summer drought is good. The trials have been going four years — enough, say Yates agronomists Ross Duder and Graham Kerr, to demonstrate persistence. High endophyte levels provide resistence against one of the two major insect pests of ryegrass, Argentine stem weevil. Until much more is known about the chemicals produced by the various fungi associated with grasses and their effects on stock and pests, Yates will promote the highendophyte cultivars because of their proven persistence, said Mr

David Lobb, a marketing manager

But the future holds promise of manufactured or inoculated ryegrasses which have insect resistance without the animal health side-effects. Selection and crossing at Courtenay is also aimed at resistance to grass grub, the other major insect pest of ryegrass. Already some genotypes with good resistance had been identified and combined. Perhaps in the future these could be married with stem weevilresistant types without the potential to cause staggers, said Dr Garth Janson, director of Yates Research, “We have found the grub-resistant types and the M.A.F. at Ruakura is working on the possible chemicals which confer the resistance,” he said.