Screening of weedicides for overspraying Eucalyptus, Pinus and Casuarina on clay soils irrigated with treated effluent.  D. W. Flinn, H. T. L. Stewart and P. J. O’Shaugnessy.  April 1980.  24 pp.  (unpubl.)

SUMMARY

A field experiment is described, which screened nine pre-emergence weedicides applied to Pinus radiata, Casuarina cunninghamiana, Eucalyptus globulus subsp. globulus, E. botryoides, E. grandis and E. camaldulensis following planting on a sandy clay soil, 33 km south-east of Melbourne. Each weedicide (nitrofen, propyzamide, oxyfluorfen, terbumeton plus terbuthylazine, simazine, propazine, chlorthal, dichlobenil and chlorthiamid) was applied to single row plots of each tree species. The application rate was varied logarithmically within each row plot of fifteen trees, and each combination of tree species and weedicide was replicated three times. The trees were fertilised and irrigated with treated municipal effluent.

On the basis of weed cover, and tree survival and growth at least 18 weeks after spraying, propyzamide was the most suitable weedicide for grass control. Effective rates had a minimum phytotoxicity to the tree species. Propazine and simazine, at low application rates, did not damage the tree species and effectively controlled a wide range of broadleaf weeds that recolonised the site. These results have application in irrigation forestry and urban situations where these tree species are extensively planted.

A tank mix of propyzamide and propazine is currently being evaluated for overspraying the species investigated.

Also published:

Flinn, D. W., Stewart, H. T. L. and O’Shaugnessy, P. J.  (1980)  Screening of weedicides for overspraying Eucalyptus, Pinus and Casuarina on clay soils irrigated with treated effluent.  Aust. For. 42 (4): 215-25.