You are all aware that currently there are three varieties available commercially: Siokra 1-2, Sicala 3-1 and DP90 (Deltapine - Acala) . Among these three, Siokra with its okra leaf, is very distinct from the other two with their normal shaped leaves. Siokra is also distinguished by it's vigour in genninarion and establishment, it's heavy production of fruiting forms and it's small, storm resistant bolls. Although Siokra doesn't usually flower any earlier than Sicala or DP90 its crop matures earlier, and it's okra leaves confer some resistance to pests especially mites. It is also practically immune to Bacterial Blight which causes severe damage in susceptible varieties. Siokra yields well under a range of planting dates and sowing conditions but does tend to lodge with a heavy crop leaving it vulnerable to boll rots and perhaps Alternaria, while it also at times suffers "premature senescence" with earlier than expected "cut-out" of either sections or the whole of the crop.

The Siratac system when it was originally conceived had no database system included in the workings of the system. On beginning to use the system however data which was accruing on individual management units could be seen to be of use to the industry as a whole. Staff of the CSIRO then set about constructing a database to allow access to the data stored on individual management units. Since the development of this database it has been used by researchers and Siratac staff for a number of uses which include:

SIRATAC users have the option early in the season of using standard thresholds or dynamic thresholds which vary between the standard level and an upper limit. Thresholds are increased if the crop is early and there will be no yield loss. If the crop is late, or if a yield loss would occur> then thresholds are reduced to base level. Dynamic thresholds aim to maintain yield and quality while avoiding unacceptable harvest delays and normally reduce the number of early season sprays by one or two. However, early crop protection is still a controversial subject within the cotton industry, and most growers do not use the dynamic option within SIRATAC.

To understand, and predict, Heliothis dynamics on cotton, along with changes in resistance levels, we must understand their dynamics on other hosts and the patterns of movement from these to cotton. The level of complexity is too great to consider conceptually and so a simulation model is necessary.

The aim of the present work is to assess the usefulness of pteridines in determining the age of adults of P. scutigera. Major practical results are outlined in the following sections - detailed procedures and data will appear elsewhere.

One such form is biological control, which relies on the use of natural pathogens and parasites to control the pest species. A group of pathogens that have been used for the biological control of several insect pests are the nuclear polyhedrosis viruses (NPVs). Five features of NPVs give them great potential for use as biological control agents

BACILLUS THURINGIENSIS use as an insecticide for 25 years despite formidable competition from conventional insecticides is largely due to its safety and compatibility. mainly with natural control but also with chemical insecticides. For example. a chemical ovicide is frequently used in conjunction with Bt for early-season Heliothis control. This combination is particularly useful in districts where a mite problem. could be induced by the use of a broad spectrum. insecticide which would destroy the natural mite predators. In Thailand,. its use against cabbage moth larvae is essential because of resistance to all alternative insecticides.

The study reported here concentrated. On these sap-suokinq bugs, which were reputed to damage seedling and early-squaring cotton

Biological control represents one alternative to insecticides. The Cotton Research Council (CRC) has funded a project to study native egg parasites of Heliothis. This work is part of a program aimed at using egg parasites to control Heliothis on cotton

My objective has been to construct life tables describing Heliothis egg and larval survival on the major crops of the Darling Downs over several seasons.