By Bec Smith, Cotton IDO
Queensland Department of Primary Industries/ Australian Cotton CRC
From Cotton Communications
This is a newsletter designed for farmers and consultants in the cotton industry in the Border Rivers region of Queensland and New South Wales, Australia. Not all information is relevant for other areas.

Macintyre Valley cotton planting kicks off

Planting is well and truly under way across the Macintyre Valley. The rain over the last couple of days may have steadied things up a bit, but not to anyone’s disappointment!

From a research and extension point of view, it is this time of year that trial sites are sought and plots are established.

At this stage there are a number of trials that I am involved in.

1. Plant Compensation under different Row configurations – this trial aims to determine the ability of skip row cotton to compensate for insect damage. Fruit will be removed at first flower to simulate insect damage. Fruiting factors and plant physiological data will be collected on a regular basis and compared to conventionally planted cotton.

2. Fusarium Wilt Trial – This trial involves the inoculation of seed with BGH, a chemical that induces the plant’s natural defence mechanism against Fusarium wilt. Plant establishment and yield will be used to determine the efficacy of this control technique.

3. Mirid Compensation trial – this trial involves injecting individual locks of bolls with pectinase to simulate the damage caused by sucking pests (Green vegie bugs, mirids etc). Similar to the compensation trials that have been run over the past couple of years, this trial will use fruit counts and yield to determine the damage caused by these pests.

4. HydroLOGIC Trial – Co-operator needed!! This trial aims to examine and demonstrate the use of HydroLOGIC, the recently released CRC irrigation decision support program in assisting irrigation decisions. Considering the season, this trial will be developed with the grower and the details of the trial will depend on the situation and it’s flexibility. If you are interested in being a part of this trial, please let me know! Updates on these trials will be in cotton tales throughout the season and the results will be published next season in the Trial Book.

If area wide groups, or individuals, would like to get together and have a look at any of these trials, please let me know. Furthermore, if you would like a copy of the protocol of any on these trials, I can forward it to you. If anyone plans on conducting on farms trials this season, there are a few simple guidelines to follow to make the results worthwhile.

Julie O’Halloran (Gwydir IDO) and Annie Sullivan have put together simple protocol that is worth looking at if you plan any trials. Let me know if you would like a copy. I am available to assist any grower or consultants with their trials.

Controlling Roundup Ready® (RR) volunteers is an important issue at planting.

Experience has shown that volunteers can be a greater problem after a dry winter. This is because there has been little rainfall to germinate volunteers before planting and volunteers then emerge at a similar time to the cotton.

With the recent rain in the area, volunteers are likely to emerge as a problem. The management of volunteers requires an integrated year round approach.

1. Rotation. When planning crop management consider rotating out of cotton the following season after a RR crop as this provides greater opportunities for alternative methods of control.

2. Monitoring. It is important to know which fields have previously grown RR cotton so that these fields can be monitored and remedial action taken if necessary.

3. Irrigation. Some control can be achieved if emergence can be stimulated prior to planting in back to back RR fields. Growers may be able to stimulate volunteer emergence by pre-irrigating fields then using one of the following management strategies for volunteer control.

4. Cultivation. After volunteers emerge cultivation does not need to be overly aggressive but must be across the entire bed.

5. Herbicides: Glyphosate If using glyphosate for general weed control then an appropriate mixing partner to control RR volunteers is essential. Glyphosate alone will not work on RR volunteers no matter what rate is applied.

Products that are either seeking registration or are registered to be tank mixed with glyphosate include Hammer and bromoxynil. Alternatively Spray.Seed can be used as a stand-alone treatment.

Hammer (carfentrazone-ethyl) is a registered mixing partner with glyphosate and has no soil residual activity. Rates of between 75 –100 ml/ha are required. It is a contact herbicide and therefore spray coverage is critical, hence performance can be enhanced with high water volumes (80 L/ha) and the addition of either Hasten™ or Supercharge™ adjuvants at 1%.

Sunlight is required to activate carfentrazone-ethyl, therefore for optimum control should be applied early in the day. Its registration is for seedlings at 2-6 leaf stage.

Bromoxynil (multiple products) registration is being sought as a mixing partner with glyphosate. Rates of 2 L/ha and greater are highly effective against seedling cotton.

Spray.Seed® (Paraquat + Diquat) is a contact herbicide that provides excellent control of seedling volunteer cotton. Registration is being sought for this purpose. Rates at approximately 1.5 - 2 L/ha control cotyledon – 4 leaf cotton easily. As with Hammer, Spray.Seed is a contact herbicide and hence high water volumes are required to attain excellent plant coverage and control.

All the above products have a different mode of action to glyphosate and can help form part of an integrated weed management strategy for controlling all weeds.

Additionally anecdotal evidence suggests that normal residual herbicides containing prometryn, fluometuron or diuron provide some control before volunteers emerge, when these products are applied as soil incorporated pre-emergent herbicides.

NEW RESOURCES & PUBLICATIONS

HydroLOGIC – This software is recognized as a valuable decision support tool for irrigation management. The HydroLOGIC CD also contains an electronic user manual and relevant Australian Cotton CRC water publications that can be printed as required or viewed electronically. This package is free and available from me at the DPI. Cotton Pest Management Guide - The latest cotton pest management guide has just been distributed. Copies are available from DPI.