TREATMENT OF EUCALYPTUS REGNANS SEED TO REDUCE LOSSES TO INSECTS AFTER SOWING

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Abstract
There is evidence to suggest that insects usually destroy the larger proportion of Eucalyptus regnans F. Muell. seed sown in the Florentine Valley in Tasmania. This paper describes experiments aimed at finding means of reducing these losses. The main seed destroying insect seems to be the Lygaeid bug, Euander lacertosas Erichson. The nymphs and winged adults, which are about 6 mm long, often occur in large numbers and are apparently capable of identifying seeds by smell. They feed on a variety of dry and imbided seeds. In a wide range of exploratory tests the seed of E. regnans was treated with insecticides, fungicides, solvents etc. by pelleting methods and momentary or prolonged immersion. Effects on viability were checked in the laboratory. With few exceptions, treated and untreated seed suffered heavy losses when exposed on trays in the field. Broadcast on representative seedbeds, germination of certain treated seeds was considerably better than that of untreated seeds, although complete protection from insects was not achieved. Seed treated with a 10% latex emulsion and stirred with an inert powder containing 2% D.D.T. and 0.1% T.M.T.D. produced two and a half times as many established seedlings as untreated seed. This method of pelleting has been used extensively and with good results throughout Tasmania.

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