Plant Testing Problem

Press, Volume CVI, Issue 31167, 17 September 1966, Page 10

Plant Testing Problem

COME work has been done k on the selection of pasture plants for tolerance of or resistance to pasture pests, but one of the difficulties encountered has been to ensure that

there have been satisfactory populations of the pests concerned in the areas where the plants have been grown. Dr. K. F. O’Connor, officer-in-charge of the Lincoln sub-sta-tion of the Grasslands Division of the Department of Scientific and Industrial Research, said this week that it had been found in Ariki ryegrass they had a fairly conspicuous tolerance of or resistance to Argentine stem weevil because they had conducted their programme of testing single plant progenies at Lincoln under conditions of high stem weevil infestation. This testing had also been done at Gore, Palmerston North and Kaikohe in the normal pattern of plant testing in the Grasslands Division plant breeding programme. Progenies which failed to do well at all four locations were rejected and since Lincoln suffered in that J’ear from a very high level of stem weevil infestation plants specially susceptible to stem weevil had been eliminated on the grounds of poor performance at Lincoln. The net effect was a measurable improvement in the tolerance of or resistance to stem weevil in Ariki ryegrass. After this success an initial attempt had been made to select within Manawa, or short rotation ryegrass, for resistance to or tolerance of

stem weevil and grass grub attack. An area had been preserved from D.D.T. for several years with such a project in mind. Separate plants of many hundreds of Manawa ryegrass progenies had been set out at the normal 2ft spacing for selection under these conditions. Unfortunately for this programme it appeared as though the weevils and grubs had not done their job. Weevil infestations apparently declined during the year of testing and the ordinary inter-plant cultivation had apparently reduced the grass grub population. As a result there had been an inadequate test of plant tolerance or resistance to these pests. Dr. O’Connor said he had discussed this matter with Mr J. M. Kelsey, of the Entomology Division, and they had agreed that in order to renew this kind of testing as part of a plant breeding project there had to be suitable means of ensuring satisfactory pest populations in conditions under which selection could be practised. With this in mind the development of techniques of ensuring this would he attempted by the Entomology Division this coming season, with assistance from the Grasslands Division*