Stinkbugs are emerging pests in cotton. In conventional cotton the use of broad-spectrum insecticides to kill Helicoverpa spp. effectively controlled the stinkbugs, but with the introduction of transgenic Bt cotton the use of broad-spectrum insecticides to control Helicoverpa spp. has been reduced. Further reduction of insecticides is expected with the increasing adoption of Bollgard II and IPM will aggravate the stinkbug problem. Little was known about their damage, thresholds, IPM tools, etc. This project addressed these issues.

In Australia there are six different types of stinkbugs- green vegetable bug (GVB), Nezara viridula (Linnaeus), red banded shield bug (RBSB), Piezodorus hybneri (Gmelin), green stink bug (GSB), Plautia affinis (Dallas), brown stink bug (BSTB), Dictyotus caenosus (Westwood), harlequin bug (HRLQB), Tectocoris diopthalmus (Thunberg), cotton stainer bug (CSB), Dysdercus sidae (Montrouzier).

Stinkbugs move to cotton from wild winter or spring crop (early mungbean) hosts when these hosts dry off or are harvested after Christmas at boll setting stage and pass at least one generation causing considerable damage to cotton. All stinkbugs cause similar damage. Damage is characterised by black spots, warty growths inside boll walls, brown coloured lint and tight lock. The damage caused by stinkbugs cannot be distinguished from the damage cause by mirids at the boll stage. The most damaging stinkbug is GVB, causing damage 2, 3 and 4 times more than GSB, RBSB/CSB and HRLQB respectively. BSTB caused negligible damage. Fourth and fifth instar nymphs and adult GVB cause equivalent damage. Third instars cause half the damage caused by 4th and 5th instar nymphs and adults. First instars do not feed and 2nd instar nymphs cause negligible damage. Bolls up to 20 days old suffer significant damage from GVB but compared to older bolls, the preferred age is 10 days or less. Bolls up to 7 days can shed due to GVB feeding. Bolls older than 25 days suffer very negligible damage and therefore do not need protection at that stage.

The most efficient method to monitor stinkbug is beat sheet sampling. In the field, distribution of stinkbugs is patchy; therefore thorough inspections at least once in a week throughout a crop are necessary. Stinkbugs are most visible during the early to mid morning when they move to the top of the crop to bask in the sun, making crop inspections easier at this time.

Once stinkbugs number reach the threshold level, control option should be selected in the light of the IPM strategy. The threshold for GVB is 1 bug (adult, 4th and 5th instar nymphs)/m with beat sheet or 0.5 bugs/m with visual counting. When calculating threshold, 3rd instar are equivalent to 0.5, and 1st or 2nd instars, clumped around the egg remnants, are equivalent to 1 4th or 5th instar nymph or adult. The thresholds for GSB, RBSB/CSB and HRLQB are 2, 3 and 4/m with beat sheet and 1, 1.5 and 2/m with visual counting respectively. As well as the insect threshold, a damage threshold can be used for management decision. US guidelines suggest a damage threshold of 20% damage to small bolls (14 days old). At least 100 bolls from a management unit should be selected randomly to assess damage and the presence of warts or stained lint deems a boll to be damaged.

For managing stinkbugs, soybean strip or bulk can be used as a trap crop. Since soybean is a preferred host of whitefly, it can be replaced with mungbean where whitefly is an issue. Since stinkbugs preferred podding stage of soybean/mungbean, the trap crop should be planted in such a way that they start podding in early January when stinkbugs move to cotton from wild hosts.

Salt mixture is an effective and profitable IPM option to manage stinkbugs. Salt at 10 g/L water mixed with reduced rate (1/2 to ¼ of full rate) chemical increase chemical efficacy by 40 % compared to low rate of chemical alone. Salt mixture increased palatability of the chemical. Mixing salt with chemicals should be approached cautiously. Chemicals that are registered for Helicoverpa, mites, whitefly and aphids should not be mixed at the low rate with salt if one of these pests is present in the field. The stinkbug spray at lower rate may have resistance implications for those pests. In terms of the IRMS, a low-rate application is counted the same as a full-rate application. If there is a maximum of three applications allowed then three low-rate applications is equivalent to three full-rate applications.

There are a number of issues that were considered before TANDOU LIMITED began trailing UNR (ultra narrow row cotton). The first was to understand the concept and visualise its best fit for our operation.

Electromagnetic (EM) surveys in combination with computer models, like Sodium-SaLF, and chloride mass balance models have been used to estimate deep drainage under irrigated soils with high clay content (Wills and Black 1996; Triantafilis et al. 1998; Zischke and Gordon 2000). In addition to these surveys and models we can also add field lysimeters. These have been used in southeast Queensland and northwest NSW to monitor nutrients that leach below the root zone of cotton crops (Zischke and Gordon 2000). This form of evaluating nutrient leaching is accurate, however, it is also expensive and requires a lot of time to install. They are a permanent fixture in the field to be studied and cannot be readily relocated to monitor multiple locations across a field.

Rising energy costs are no surprise to farmers. Peak oil and an exponentially expanding world population are maintaining strong upward pressure on the price of energy.Cotton is sensitive to energy price because it is a high-input crop that relies on energy intensive inputs such as diesel fertilisers and chemicals. This is why the Cotton Research and Development Corporation (CRDC) has initiated projects to meet the energy challenge for Australian cotton production into the future.

Water-use efficiency of cotton production and minimising the impact of the cotton industry on the environment have emerged as issues of great importance. To improve these issues two major questions need to be answered: 1. How much water is draining from the irrigation system? 2. Where does the water go once it moves below the root zone.

The following is a summarised version of a paper written on research into two potential reference methods for a NIR fibre maturity and fineness instrument being developed at the United States Department of Agriculture's (USDA) Southern Regional Research Center (SRRC). The objective of the research was to compare values of perimeter and wall thickness derived from the values given by two instruments; the Shirley Micromat and the Zellweger Uster Advanced Fibre Information Systems Fineness and Maturity Module (AFIS F&M). The aim was to choose one of the instruments as a reference method for calibrating NIR spectroscopy. Comparisons were made on the level of error associated with each method and the degree to which data from each method conformed with theoretical relationships.

ABSTRACT

The Pacific damsel bug, Nabis kinbergii, is a potentially important predator of key cotton pests. Aspects of Pacific damsel bug behavioural ecology, particularly feeding behaviour, were investigated to develop a better measure of rates of predation on cotton pests. Direct observation studies in the glasshouse showed that the frequency of observer presence had no influence on Pacific damsel bug distribution and activity or prey (heliothis) mortality and distribution, during diurnal and nocturnal observation sessions. This represented the first documented test of observer presence in an insect species, and provided justification for future observational studies of Pacific damsel bug behaviour (Chapter 3). Pacific damsel bug behaviour did not vary significantly during diurnal periods in the field, but in the glasshouse feeding behaviour was greatest at dawn and during the morning. Further observations revealed that bugs fed at the same frequency during diurnal and nocturnal periods in the glasshouse. Knowledge of diel variation in Pacific damsel bug behaviour would be useful for predicting optimal times to Observation and inclusion cage studies in the glasshouse and field determined that Pacific damsel bugs fed on prey and cotton extrafloral nectar, but not on intact plant tissue. Pacific damsel bugs should be treated as an omnivore and beneficial, but not a pest species of cotton, and may respond positively to application of artificial food supplements to crops , count, collect and manage these arthropods.

The introduction of transgenic cotton expressing the CrylAc insecticidal crystal protein from Bacillus thuringiensis (Bt) is expected to provide the basis for pest management in cotton in the near future and to reduce the usage of pesticides in the industry. However the potential for over-reliance on Bt-cotton to result in the development of resistance to Bt by Helicoverpa armigera has been identified (Edge, 1994). Recognising that his resistance would undermine the basis for pest management the cotton industry has devoted resources to addressing the problem. Experience with resistance to synthetic chemical insecticides has shown that there are options for managing resistance. One of the major options being examined is the provision of alternative means of control that will complement the Bt cotton. Among these alternatives is the identification of new insecticidal crystal proteins from Bt. Over the past four years an additional 35 Bt insecticidal crystal proteins have been recorded, demonstrating that the diversity of these insecticidal toxins is much greater than previously recognised. We have taken advantage of new molecular technologies to search for new insecticidal crystal proteins that can be used to complement CrylAc in a resistance management program.

The research into aphid bio-control in cotton has documented the agents attacking cotton aphid in southern and central Queensland, and provided an indication of their relative importance.

When aphids are invading cotton crops in the summer, a complex of predators (particularly adult ladybirds) can prevent or severely restrict aphid establishment in the crops. Predators can also restrict aphid population increase within the crop.

When aphid populations reach high numbers in cotton crops, parasitic wasps can completely wipe out these populations within a few weeks.

Many weed species are hosts of the cotton aphid, but only a few are used by the aphid to maintain its survival over the winter months, when cotton plants are unavailable. These weeds should be controlled to reduce over-winter survival. However some weeds, which harbour other aphids, which do not attack cotton, play an important role in maintaining bio-control agents of cotton aphid over the winter months.

Barley crops also often harbour enormous numbers of bio-control agents and is a reservoir of bio-control agents in the late-winter and spring period.

Adoption of these findings by cotton growers will allow them to make a more objective and rational evaluation of the usefulness of the natural enemies they find in their crops. This information can be used to guide decisions about spraying for aphid control, particularly under the low spray regimes in Bollgard cotton.

The CRDC Researcher’s Handbook 2014-15 is a key resource for all researchers working with, or interested in applying for funding from, the CRDC.