Travel grant: 9th Biennial Conference Australasian Plant Pathology Society

A review of findings presented at the 12th Congress of the International Association of Agricultural Medicine and Rural Health

A thesis submitted for the degree of Doctor of Philosophy in the School of Agricultural Science

OBJECTIVES OF VISIT: (i) To attend and present a paper and a poster at the Sixth International Verticillium Symposium, Dead Sea Israel. (ii) To have discussions with Israeli reseachers at the Volcani Institute on Alternaria leaf spot of cotton

The objectives of Dr Byrne's visit to Australia were: 1. For Dr Byrne to present a paper to the special whitefly workshop at the World Cotton Research Conference in Brisbane, February 1994 on "Resistance biochemistry of the cotton whitefly Bemisia tabaci". 2. To assist Dr Gunning to initiate some baseline toxicological and biochemical studies to assess the resistance potential of B. tabaci on Australian cotton crops. 3. To discuss colaborati.ve research on Helicoverpa resistance biochemistry between Dr Gunning and the Rothamsted Insecticide Resistance Group.

Aims: 1. To determine the rates, form and placement of fertiliser appropriate to alleviate potassium deficiency and premature senescence. 2. To further research the role of potassium in the resistance of cotton to Altemaria leaf spot.

Report on Overseas Travel, June-July 1994 Helen McFadden

The funds requested in the application were for Dr Christian to spend 6 weeks in the laboratory of Dr Art Mcintosh and Dr Carlo lgnoffo in Columbia Missouri, working on aspects of the project "Genetic Engineering of Heliothis Nuclear Polyhedrosis Viruses: Pre-commercial Development" Dr Christian and Ors Mcintosh and lgnoffo have an on-going collaboration looking at various aspects of the biology and ecology of Helicoverpa nuclear polyhedrosis viruses (HaNPV). As part of this collaboration Dr Christian had previously spent three months in Columbia in 1992 studying aspects of the in vitro production of HaNPVs and their in vivo activity against a variety North American noctuid species. The collaboration continued further when Dr Mcintosh undertaking a six month McMaster's Fellowship in 1992/93 in the Division of Entomology to develop new cell lines from Australian Helicoverpa species

In order to obtain information of its environmental fate under conditions of use in the Australian cotton industry, this major study was initiated in 1990-91. It represented the first case of a systematic analysis of the fate of endosulfan under Australian conditions. The experimental strategy used was to conduct random sampling of soil throughout the year on several fields used for cotton growing. From analysis of these soil samples for endosulfan residues, it would be possible to discover the rate of breakdown and to estimate half-lives (the time to reduce the concentration in soil to half its current value) and to identify the chemical products. This would allow an assessment of whether endosulfan was likely to cause long-term problems related to its accumulation in soil and its potential threat to the environment.,

During this trip I was able to liaise successfully with the following colleagues concerned with resistance and its management: Drs Rick Roush (Cornell), Alan Devonshire (Rothamsted), Chris Curtis (London School of Hygiene and Tropical Medicine) and Alan McCaffery (Reading University). Outcomes of the discussions were: (1) I received affinnation that the likely nature of the pyrethroid resistance recently detected in St George, was an esterase-mediated mechanism, as suggested by Dr Robin Gunning. I established contacts relevant to the new project on the esterase resistance in Helicoverpa armigera. Clones for the para gene for kdr resistance and for esterases were made available. (2) I was given up-to-date information on pyrethroid resistance studies in H.. armigera in India and Thailand, and Heliothis virescens in the USA. It appears that kdr type resistance is not common in Asian populations of resistant H. armigera as was first thought. In particular, the dominant form of pyrethroid resistance in India is metabolism Endosulfan resistance has been detected in Pakistan H. armigera. (3) I discussed different aspects of resistance management to transgenic plants. As a result, I have become concerned about the directions being taken in models overseas that seem biased towards seed mixtures as the preferred control strategy. This bias arises more from social/political constraints in the USA cotton industry than because it necessarily is the only viable option to manage Bt plants. However, seed mixtures do seem to be the 'best' biological option in potato crops for the control of Colorado potato beetle because this insect is not very mobile