Protection of direct-sown eucalypt seeds from destructive organisms.  II Screening of some commercial pesticides for use as protective seed coats of eucalypts.  F. G. Neumann and F. Y. Kassaby.  January 1982.  20 pp. (unpubl.)

SUMMARY

The results are presented of laboratory and field tests on the effects of 13 commercially available pesticide products on seed and germinants of Eucalyptus delagetensis R. T. Baker (Alpine ash), E. fastigata H. Deane & Maiden (cut-tail), E. nitens (H. Deane & Maiden) Maiden (shining gum), E. obliqua L’Hérit. (messmate stringybark) and E. regnans F. Muell. (mountain ash), and on the effectiveness of some of these pesticides as protectants of E. regnans seed, on an operational, low-elevation, ash-bed site near Powelltown, in the Upper Yarra Forest District. About two-thirds of the pesticides were moderately or severely phytotoxic, when applied with kaolin, or in undiluted form, to the seed testas of all five eucalypts. Symptoms of poisoning were: reduced germinative capacity of seed lots, and/or poor quality germinants (in terms of seedling length, root:shoot ratio and seedling oven-dry-weight).

Fungicides containing copper or thiram or high concentrations of mancozeb, carboxin or benomyl, appeared to be especially phytotoxic. The effects of some of the pesticidal treatments varied considerably between different eucalypt species, highlighting the importance of specifying the eucalypts that are tolerant to any pesticide prescribed for seed protection.

Commercial R and T Special Tomato Dust^† (a mixture of insecticides 2% DDT and 0.5% lindane, and fungicides 5% mancozeb and 40% sulphur), diluted 1:1 with kaolin, showed potential as an effective protectant of E. regnans seed in the field, over a total period of two months between late winter and early spring; whereas the other eucalypts tested were adversely affected, especially E. obliqua. Further field evaluation of new adhesives and of bulking agents, of Special Tomato Dust and of other commercial pesticides, is considered necessary, before current, interim, Forests Commission seed coating prescriptions can be improved.

^†Registered trade Name. Use of trade names is for the information and convenience of the reader. Such use does not constitute official endorsement or approval by the Forests Commission Victoria of any product to the exclusion of others that may be equally suitable.