Climate change: Emerging pests, diseases - a new microscopic world
Myrtle rust is just one pest in a growing range of threats that come from climate changes. With 2016 our hottest year on record and this January the hottest month recorded, it is difficult to ignore that our climate is changing. Temperatures are predicted to further increase, making frosts a thing of the past for us in the Waikato. But unlike our Australian cousins, on the whole New Zealand agriculture shouldn't be negatively affected by climate change, with productivity actually improving in some regions. According to NIWA forecasts, annual rainfall won't change too much in the Waikato over the next 70 years it will just be hotter and the plants, animals and diseases around us will change with it. Changes will provide opportunities to use higher yielding plants and breed animals with better heat tolerance to increase productivity, but there are risks too. Historically we have done a good job keeping diseases out of New Zealand but the reality is that many pests and diseases just can't survive our climate. In the future that will all change as our climate becomes more suitable for subtropical pests. This coupled with increased volumes of trade with Asia will accentuate the risk. Imports from this region already account for over half of New Zealand's imports and are predicted to increase. Unfortunately this all favours the establishment of new exotic pests and diseases that damage human and animal health, crops and natural ecosystems. Of particular concern is the establishment of vectors like ticks and mosquitoes that spread animal and plant diseases. Subtropical insects will have the potential to devastate horticulture and legume crops. Insects like the glassy winged sharpshooter and giant sapsucking whitefly which is known to infest at least 35 plant families, including New Zealand native plants. Human diseases like malaria, Ross River virus and dengue fever could become commonplace, as well as animal diseases spread by subtropical insects like Q fever, tick fever, West Nile virus and bovine ephemeral fever virus. These diseases sound exotic now, but those names could be all too common in a generation. We already have some pests in New Zealand which are isolated to small pockets like locusts and armyworms. These are known as sleeper pests because under warmer conditions have the potential to spread and multiply, devastating pastures and crops. With greater exposure to the world at large through trade and tourism, we have seen more diseases like varroa, theileria, didymo, myrtle rust and mycoplasma in the last few years and we can only expect more and more new diseases in the future. Right now you can protect your farm with biosecurity measures. This makes good sense now to stop existing pests and diseases at the farm gate but will be essential in years to come. We can also support the development and use of novel crops resistant to disease and better suited to hotter climates. As an industry we are aware that change is imminent and will have to adapt to what's ahead. After all, the only certain thing in life is change. Harry Gaddum, Todd Clark, Tom Taylor and George Macleod, the Stus, Chris Brandolino.