Plant Breeding Mooted

Press, Volume CVI, Issue 31161, 10 September 1966, Page 8

Plant Breeding Mooted

Breeding of resistant grasses and clovers was mooted by Dr. H. C. Smith, director of the Crop Research Division of the Department of Scientific and Industrial Research, at a meeting in Christchurch last week on the porina and grass grub problem.

At the time the meeting was considering , whether research was on a big enough scale, was sufficiently coordinated and whether other approaches to the problem had been explored.

Dr. Smith said he thought that the Grasslands Division should put a major effort into breeding resistant grasses and clovers. There was quite an active lucerne breeding programme at Lincoln under Palmer, he said. It could be an opportune time for him to put his hybrid material into the Carew area so that selections could be made for resistance to these insect pests. But Dr. J. M. Hoy, director of the Entomology Division, cautioned against undue optimism about breeding pasture plants for resistance to these pests. The grass grub was a general feeder, he said. He did not think that it mattered to it whether it was a root of ryegrass or lucerne. If it was a deeper feeder there might be a case for breeding a plant the roots of which ran laterally below the

surface of the ground, but the grub would feed right up to the crown of the plant. It might be worthwhile looking at some chemical factors in plants that made them more attractive or otherwise to grubs. The sooner a start was made on such a programme like this the sooner something definite would be found out, said Dr. Smith.

Mr J. M. Kelsey, of the Entomology Division. Lincoln, mentioned that cocksfoot and browntop showed more resistance than other plants in that they could send down new roots.

Would rolling a paddock at night be any good for the control of porina, asked Mr J. F. N. Twose (North Canterbury Federated Farmers). Mr Kelsey said that this would not be any good as at any ground vibration they went down their tunnels right away. He said that some farmers at Fairton had put their dogs round the sheep at night in the hope that the treading action of the sheep would l?e helpful, but there had been no reduction as far

as their sampling had indicated. It had, however, been shown in other trials that there was a 49 per cent reduction with concentrations of cattle and a 32 per cent reduction with concentrations of sheep. Cultivation got rid of grubs, said Mr Kelsey. Grub numbers could be reduced from more than 63 to the square foot to under one with five grubbings if birds were following each cultivation.

There were, in Canterbury, Mr Kelsey said, eight different predators or parasites of porina and 18 different native parasites or predators of grass grub, but from the level of i damage that was being sus-l tained Dr. Hoy said that they I were not having as desirable' an effect as they would like. I