Publication Date
1993
Description
Damage threshold levels were established for adult Argentine stem weevil (Listronotus bonariensis (Kuschel)) feeding on Italian ryegrass (Lolium multiflorum Lam;) cv, Concord seedlings in a glasshouse pot trial. Population densities of 35-70/m1 reduced seedling survival by 34% and herbage yield after 28 days growth by 35%. A field trial was established In autumn 1991 by sowing Concord in early February, in late February and in March into areas previously treated with glyphosate herbicide, Insecticide application increased ryegrass tiller density by 36% from 2339/m' (April 1991) and herbage accumulation by 43% from 1.4 t DM/ha only up to the first grazing (approximately 6 weeks after sowing). No increases in tiller density and herbage accumulation due to insecticide treatments occuned after this period. Argentine stem weevil (Listronotus bonariensis (Kuschel)) populations were 8-20/m2 and were unlikely to fully account for the grass response to insecticide treatment. Other root· pruning insects occurred at combined densities of 33-63/m2, Plant nematode genera occurred at low densities. Populations of Pratylenchus occurred'at 122-652/g of root and were reduced 49% by insecticide treatment. Root feeding notches possibly caused by root aphids were very abundant on most seedling roots and were significantly less on insecticide treated plots. Collective control of the insects ·and plant pathogenic nematodes probably contributed to the seedling ryegrass response to insecticide treatment.
Citation
Prestidge, R A.; Watson, R N.; and Thom, E R., "Invertebrate Pests Associated with Italian Ryegrass in Northern New Zealand" (2024). IGC Proceedings (1993-2023). 18.
https://uknowledge.uky.edu/igc/1993/session22/18
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Invertebrate Pests Associated with Italian Ryegrass in Northern New Zealand
Damage threshold levels were established for adult Argentine stem weevil (Listronotus bonariensis (Kuschel)) feeding on Italian ryegrass (Lolium multiflorum Lam;) cv, Concord seedlings in a glasshouse pot trial. Population densities of 35-70/m1 reduced seedling survival by 34% and herbage yield after 28 days growth by 35%. A field trial was established In autumn 1991 by sowing Concord in early February, in late February and in March into areas previously treated with glyphosate herbicide, Insecticide application increased ryegrass tiller density by 36% from 2339/m' (April 1991) and herbage accumulation by 43% from 1.4 t DM/ha only up to the first grazing (approximately 6 weeks after sowing). No increases in tiller density and herbage accumulation due to insecticide treatments occuned after this period. Argentine stem weevil (Listronotus bonariensis (Kuschel)) populations were 8-20/m2 and were unlikely to fully account for the grass response to insecticide treatment. Other root· pruning insects occurred at combined densities of 33-63/m2, Plant nematode genera occurred at low densities. Populations of Pratylenchus occurred'at 122-652/g of root and were reduced 49% by insecticide treatment. Root feeding notches possibly caused by root aphids were very abundant on most seedling roots and were significantly less on insecticide treated plots. Collective control of the insects ·and plant pathogenic nematodes probably contributed to the seedling ryegrass response to insecticide treatment.
