CottonInfo and CRDC held an Integrated Pest Management (IPM) workshop series in late November and early December – taking the message of IPM out to 130 growers and consultants across five cotton growing valleys.
Experienced industry researchers’ Dr Lewis Wilson, Dr Mike Bange, Dr Robert Mensah, Dr Paul Grundy, Dr Jamie Hopkinson and Dr Sandra McDougall were among those who presented at the workshops, which took place at Warren, Griffith, Cecil Plains, Boggabilla and Boggabri.
The workshops had two clear messages for growers and consultants: IPM plays an essential role in helping to avoid insecticide resistance, and you can achieve high yielding cotton using IPM.
According to CRDC’s R&D Manager Susan Maas - who also presented at the workshops along with CottonInfo IPM technical specialist Sandra Williams - while Bollgard 3 offers additional resilience against cotton’s primary foe, Helicoverpa spp, there are growing risks of widespread insecticide resistance forming in many other pest species if the principles of IPM are ignored.
“Researchers have recently detected rising levels of insecticide resistance in silverleaf whitefly to a cornerstone product. Resistance in mites is already present and sucking pests such as mirids could be next,” said Susan.
CSIRO’s Dr Wilson said the cotton industry must continue to strive for a strong IPM system to support Bollgard 3.
“If we drift into increased use of sprays in the belief that this is keeping retention high and pushing up yield then we risk the future that has happened in the United States’ Mississippi Delta,” Lewis said.
“Growers there are now spraying more in Bt cotton than they were in conventional cotton.
“This is due to resistance to insecticides in Lygus, emerging Bt resistance in Helicoverpa and increasing secondary pest problems (like mites) as a result of increased spraying.
“We don’t want to end up there, so we need to realise that while Bollgard 3 is a great platform for IPM, it also benefits from the support of a strong IPM system.”
In Australia, CRDC’s annual insecticide monitoring programs have detected increasing resistance to key products in silverleaf whitefly and mites. Both are species that flare easily and require careful IPM to manage effectively.
Insecticide resistance monitoring is an essential component of the cotton industry’s Insect Resistance Management Strategy (IRMS) with results of the program used to ensure the IRMS remains effective and relevant to the country’s dynamic insect populations.
“Industry thresholds provide guidance on when to control pests so as to maintain yields and quality,” Susan said.
“However we are seeing some concerning trends emerging and need to be proactive in our approach to insect management through IPM.
“It is concerning that although we don’t really see mite issues in Australia, we are seeing resistance, due to the use of prophylactic spraying. This was flagged in the IRMS this year where the need to use thresholds was highlighted.
“Knowing thresholds for control of insect pests are aces we hold in our hand: we know what populations have to be at to start causing damage, yet we are seeing untimely or unnecessary applications. This unnecessary spraying can then trigger problems in other pests and the problem amplifies.”
With this year ramping up to be a high pressure year, maintaining beneficial predators is going to be more important than ever and crop managers must choose products wisely in terms of the flow-on and flaring effect they may have later in the season. This signifies the need for IPM to be a year-round program.
To grow high-yielding crops pest management must be viewed as a ‘whole season’ approach. Early season insect management impacts late season pressure.
“For example what are you doing for thrip management now? And how will that affect your options late season?” Susan said.
“We also need to get away from the thinking that because individual fields or hotspots have reached their threshold that the whole farm needs to be sprayed.
“If you hit mirid threshold in one field – don’t spray the whole farm – keep some beneficials in other areas.”
Regular flaring of insects such as silverleaf whitefly and mites can be a symptom of a loss of beneficials earlier in the season.
“If you have a lot of beneficials these pests can be less of a problem to manage,” Susan says.
The concern is we are seeing whitefly problems year-on-year which suggests they’re no longer just based on seasonal conditions - and at the same time we are seeing rising resistance levels to the best product we have for control.”
Mealybug is a pest that there are no good chemical control options for – it is only through IPM this pest can be managed. The recent detection of Solenopsis mealybugs in Victoria is troubling, says Susan.
“When mealybug show up you will be looking back through what you’ve done during the season and wishing you had an IPM approach from the start,” Susan said.
For more information, download IRMS (found within the Cotton Pest Management Guide: www.cottoninfo.com.au/publications/cotton-pest-management-guide)
