Arable growers will face significant technical challenges by 2020 – as loss of chemistry and resistance, as well as climate change, will add to the pressure to produce sustainable crops. That’s the message from key thinkers in the industry – but there are strategies to combat the problems.
One of the biggest constraints growers face is the loss of active ingredients, says Rothamsted’s Maurice Maloney. The EU carries the can, he says, because of its relatively unscientific approach to eliminating active substances – basing policy on intrinsic hazard, rather than the risks in use.
The consequences will be major. “The problem is that if you narrow down the base of chemistry you’ll generate resistance relatively soon,” he says.
To protect remaining chemistry, Prof Maloney says growers will have to focus their attention on alternative technologies or well-planned product stewardship.
Unfortunately, the UK hasn’t had the benefit of alternatives such as GM, which could alleviate the pressure on the system. “If you could rotate herbicide-resistant oilseed rape every two to three years, we wouldn’t have a blackgrass problem,” he says.
The NFU’s Guy Gagen agrees that the system is fraught with uncertainty and with less investment in new products and stringent registration requirements, fewer new active ingredients are likely to come through the pipeline.
Blackgrass will continue to plague growers and could, if chemistry is revoked or eroded by resistance, render certain crops uncompetitive to grow. “Grassweed herbicides are already limited in pulses and barley. If blackgrass could not be controlled in oilseed rape and wheat, the yield reductions are quite stark – around 40% for each crop.”
In future, growers will need to plan ahead and be prepared to change rotations, consider alternative non-food cropping, and focus on cultural control options, however limited they might be, he says.
Resistance will also narrow the chemistry base. Neonicotinoid resistance in Myzus persicae could leave sugar beet totally exposed to aphid infection, forcing growers to explore alternative control strategies, says BBRO’s Mark Stevens.
Changing strains of rhizomania are a big threat to growers and a challenge to breeders to produce durable resistance to the vector rather than the virus, he says.
NIAB TAG’s Bill Clark believes fungicide resistance will be the biggest threat within the next decade. The complexity of Septoria tritici mutations has surprised everybody and they pose a real threat – the potential loss of triazoles would be disastrous, he says. “Growers would be unable to grow the current range of wheat varieties due to septoria pressure. If we were to lose the triazoles then SDHIs would go as well. Then within a decade we would lose the only two effective fungicide groups against major cereal diseases.”
Elicitors – molecules that induce plant resistance mechanisms – might become realistic components of integrated crop protection strategies, says HGCA’s Simon Oxley. “These methods may be a bit more challenging to use, but the industry needs to look at these in light of potential reduction of fungicides,” he says.
Climate prediction models estimate milder winters and warmer springs and summers in the future. Within this trend, growers will also face the seasonal extremes of drought and wet, challenging their ability to produce consistent quality and yield across a range of conditions.
Rotations in 2020 might change, says Mr Gagen. “People may start switching to other crops such as grain maize or maybe to soybeans because of climate and availability of crop protection.”
Growers will also face the challenge of producing better habitats for pollinators and birds, he says: “We have a responsibility to look after the environment. They suffer the same threats from volatile weather and climate change.”
There will be pressure on breeders to produce more climatic resilient varieties, and a challenge for growers to adapt to these, while becoming less focused on yields.
Pests and diseases are likely to benefit from the changes in climate, and while the current ones are likely to remain, there is potential for a shift in emphasis in terms of incidence and severity, which could cause growers problems in terms of management, says Mr Clark.
A switch from Septoria tritici to Septoria nodorum or tan spot could occur in the matter of a decade – commanding different fungicide programs on wheat, he says.
Independent wheat consultant Bill Angus is worried that insect pests for which there is no genetic resistance – such as lemon blossom midge – might increase.
Soil-borne pathogens concern sugar beet and potato crop specialists. “If soils warm up faster, then anything that attacks a spring-sown crop potentially has a greater impact on yield performance,” says Dr Stevens.
More generations of beet cyst nematode within a season – combined with tighter rotations, and a lack of genetics and chemistry – are also concerns. “If we don’t develop strategies to get on top of that, it is going to be a major issue and may drive where you can and can’t grow crops going forward,” he says.
Viral diseases might increase as aphids are better able to overwinter in milder conditions and migrate into crops, spreading viruses. The lack of insecticide chemistry and resistance means varietal resistance becomes more important, he adds.
Sugar beet growers may also experience problems at the other end of the season with more challenging, wetter harvest conditions and warmer soils favouring violet root rot and fusarium. “There are no chemicals or genetics to tackle those,” he says. “It could particularly be a problem if beet is left in the ground for longer term storage. We need strategies to combat those issues as well.”
According to Mike Storey of the Potato Council, the aggressiveness of potato blight strains could develop, and blight pressure could increase with a changing climate. Potato cyst nematode (PCN) will also become more difficult to control if nematicides are lost, he says.
Growers should gear up to looking to alternative controls for PCN and rhizoctonia through integrated strategies, including bio control agents and biofumigation. “Biofumigants have the additional benefit of improving soil organic matter. The importance of good soils has shown itself this year,” he says.
Potato growers will be well placed to exploit a changing climate, according to climate projection work. Predicted temperature rises put the UK in a better position than other areas of Europe.
A better understanding of the potato genome will drive innovation in storage and novel varieties, whilst DNA diagnostic technology for testing seed and providing information on diseases will help with planning or making decisions about chemical use, he says.
As production becomes more scientific, growers themselves will have to become more informed and the industry will have to upscale its technical advice, says Mr Storey.
Plant breeding pressures
Loss of chemistry, weather fluctuations and increased energy costs are expected to put pressure on the plant breeding industry to develop nutrient efficient, climate resilient varieties that offer durable disease resistance and improved yields.
For wheat growers, the challenge will be to leave old fashioned ways behind and start thinking in terms of handling bags of genes with strategic use of genetics and chemistry, says Mr Angus. “We have to gear up to handling varieties in a different way. Growers need to be more precise in terms of variety choice, rotational position, disease profile and end use market, really drilling much deeper into the characteristics of the wheat.”
Mr Clark is concerned that conventional breeding might not deliver rapid advances in genetics required. However, he is positive about the potential of novel breeding techniques such as NIAB’s synthetic wheats. These aim to offer genetic diversity, great leaps in yield and shorter time to market.The challenge for growers will be to adapt to these new types of variety.
It will require more skills of a grower to get the most economic yields out of a variety which may not be the top yielder but will perform over a wide range of climatic conditions – and this will include a reliance on integrated control of pests and diseases. Growers will need to be more sophisticated and skilled, and look to long term rotational planning, looking ahead to five, 10 or even 15 years.