An improved technique for early detection and control of theSirexwood wasp in radiata pine plantations

Abstract

Basal stem injection of Dicamba herbicide (20% 3,6-dichloro-2 methoxybenzoic acid) into the outer sapwood was tested as a technique for predisposing conveniently placed groups of Pinus radio/a trees to attack by the European tree-killing wood wasp Sirex noctilio. The trials included injection of Dicamba during spring and summer, injection of de-ionised water during spring and untreated controls, and were undertaken in unthinned plantations of two ages, 8 and 15 years.Sirex noctilio was attracted almost exclusively to the Dicamba-treated trees, which provided suitable breeding habitats for the pest and its introduced natural enemies, both wasp parasitoids and nematode parasites. Spring injection gave more satisfactory results than the summer injection. The trees in the older stand were more susceptible to attack, as were the trees in the smaller diameter classes in both stands. Infested treated trees contained an average of 275 wasps irrespective of tree age. Dicamba injections did not induce major attacks on any nearby untreated trees.The practical importance of these findings is that S. noctilio can now be readily detected, its populations periodically monitored, and control improved in plantations, by attracting the pest, and its lethal wasp parastoids, to strategically placed and widely distributed groups of Dicamba-treated 'trap' trees. Inoculation of the trees with the nematode parasite, De/aden us siricidicola, which infests S. noctilio larvae, will cause the infested females which subsequently emerge to be sterile and, as a result, the population is expected to fall.

Trapping Techniques for Siricids and their Parasitoids (Hymenoptera: Siricidae and Ibaliidae) in the Southeastern United States

“…A confounding issue is timing, as trees were treated with Dicamba in late September, which is in the early part of (or even before) the siricid ßight season. In the Southern Hemisphere, trap trees for detection of S. noctilio were created 2Ð3 mo before peak ßight period (Neumann et al 1982). In New York, injecting Dicamba into the tree stem 1 mo before peak ßight or at ßight season captured the greatest numbers of S. noctilio (Zylstra et al 2010).…”

“…is diglycolamine salt; 480 g/liter; Vanquish, Syngenta Crop Protection, Inc., Greensboro, NC) in a distilled water solution into a 6-to 7-cmdeep and 10-mm-diameter predrilled hole every 10 cm around the treeÕs circumference. Holes were Ϸ15 cm above ground level and drilled at a downward 45Њ angle (Neumann et al 1982, Neumann andMorey 1984). The number of drilled holes ranged from Þve to eight per tree and the absolute amount of the a.i.…”

Susceptibility and Response of Pines to Sirex noctilio

“…11 , 12 ). However, evidence continues to suggest that additional volatile compounds may be involved in signaling since girdled and/or herbicide-treated trap trees (Madden 1971 ;Morgan and Stewart 1972 ;Neumann et al 1982 ;Simpson 1976 ;Simpson and McQuilkin 1976 ) nearly always outperform artifi cial traps baited with the recommended mixed-pinene lure.…”

Influence of natural enemies on theSirexwood wasp in herbicide-treated trap trees of radiata pine in north-eastern Victoria

“…Fieldwork was carried out between October 1979 The herbicide treatments were carried out as part of an extensive experiment involving 14 336 trees to test whether S. noctilio, and any of the established parasitoids, could be preferentially attracted to them (Neumann et al 1982). An additional 30 Sirex-infested, 1 m long billets were similarly selected during winter 1981 from another 72 trap trees which had received dicamba injections on 14-15 January 1980 and which had become infested by S. noctilio during summerautumn 1981.…”