Previous research at Narrabri Agricultural Research Station and elsewhere has shown that mite populations increase more slowly on okra leaf cotton genotypes than on normal leaf genotypes (Bailey et al., 1978; Thomson, Reid and Fitt, 1984; Wilson and Pitt, 1987). Experimentally this difference has resulted in far lower yield reductions on Siokra than DP90 when artificial mite infestations were initiated in each variety at the same time. This paper summarizes the findings of experiments designed to determine the underlying cause of the resistance to mites found in the okra leaf genotypes and also reports some more recent findings

The cornerstone of most pest management programs world-wide is the "Economic Threshold" concept which is based on the principle of controlling a pest only if it is economically prudent to do so i.e. the cost of control is less than the value of yield loss caused by the pest. To implement this concept effectively three key criteria must be met. Firstly it must be possible to estimate the abundance of the pest accurately, secondly a rapid curative control must exist, such as an insecticide or miticide, and finally the relationship between the abundance of the pest and reductions in the economic value of the crop must be known. All of these criteria are now met for mites on cotton in Australia.

At the last ACGRA conference in 1990, it was reported that the Heliothis ID project had been running for approximately six months and species specific antibodies had not yet been obtained. Here we report the production of suitable species-specific antibodies, the design of a prototype kit, some successes and problems encountered in field trials and current work being undertaken to develop the kit to a commercial standard.

Helicoverpa punctigera (Wallengren) and H. armigera (Hubner) have a number of characteristics which make them highly successful pests of numerous crops in Australia, including cotton (Fitt 1989). They are highly mobile, have a broad host range and can increase in numbers rapidly when conditions are favourable. Current pest management relies on regular sampling and application of pesticides when thresholds are exceeded. It seems unlikely that the need for regular crop checking can ever be abandoned, but here we discuss prospects for predicting changes in Helicoverpa abundance which may assist pest managers in the future

Nutgrass (Cyperus rotundus L.), a plant native to India, is known as the world's worst weed . It is a member of the family Cyperaceae, which contains approximately 3000 species, of which about 220 species are important weeds . Nutgrass is cold sensitive , only growing during the warmer months and will not survive in the colder parts of Australia. It is adapted to most soil types and soil moisture regimes

In 1990, a C.R. & D.C. co-operation with the funded research project was begun, Industry Hail Scheme Insurers, to investigate and evaluate the hail response of cotton varieties currently grown in the Australian cotton industry. While the research will increase our understanding of the cotton plant's response to hail damage and may also identify better management practices to maximise recovery potential, the information collected will also enable the current loss assessment procedures to be updated as necessary.

As the Cotton Breeder for Deltapine Australia this presentation will concentrate on the breeding program and aim to cover the following *The performance of Deltapine Varieties in 1991 /92 *The specific factors Deltapine is breeding for in Australia *The future

The performance of CSIRO varieties and new lines are evaluated each year in a series of regional trials, known as the Australian Cotton Cultivar Trial (ACCT). CSIRO and the QDPI have been running these trials since the 1974/75 season. Currently the ACCT comprises thirteen sites representing all the major cotton growing areas. This wide testing provides a good estimate of overall performance while also enabling assessment of whether particular genotypes perform relatively better at some environments than others.

The CSIRO breeding programs aim to produce varieties for all the different growing situations in Australia. Situations where special varieties are very important are for cooler growing areas and for Verticillium wilt infected soils. This paper will discuss our short season varieties and Sicala V 1 which, although not early maturing, is adapted to the cooler and Verticillium prone areas. A discussion of our varieties developed for the mainstream production areas can be found in the paper by Norm Thomson

Last season there were four (Siokra 1-4, Siokra L22, Sicala 33 and CS 189) CSIRO mainstream varieties being grown commercially in most districts. In addition the new variety CS 50 was trialled in most areas as was Sicala 34, the higher strength replacement for Sicala 33. In some districts, our three special purpose varieties (Sicala Vl, CS 7S and Siokra S324) were a.lso grown. Peter Reid will discuss their performance in his article.