Syngenta technical lead Scott Mathew says that as the temperature gauge increases so too does the likelihood of an outbreak of the fungus.
“While powdery mildew in carrots was only identified in Australia in 2007, what we know so far is that it finds the late summer months ideal as it thrives on warm and quite dry weather,” Scott says.
“It is also often hard to identify, with the small white spores on the carrot leaf often going unnoticed until the outbreak is severe.”
Since being first discovered in New South Wales four years ago, powdery mildew has now been identified in South Australia, Tasmania and Queensland.
The NSW Department of Primary Industries has been researching the disease in carrots and Plant Pathologist Andrew Watson has recommended in his report on powdery mildew (Erysiphe heraclei) that the disease be identified as early as possible and sprayed immediately.
“The impact that powdery mildew has on carrot yield is twofold. Research done in greenhouses has shown that it can directly impact yield by up to 20 per cent,” Andrew says.
“Additionally, as it impacts the strength of the carrot leaf, yield loss often occurs where the carrots are lifted out of the ground by the leaves, with some carrots being left behind.”
The growing need for an early curative crop protection product to fight this fungus has resulted in Amistar Top® becoming the first early curative control product to receive registration for carrots in Australia.
Scott says this will be an important weapon in the fight against powdery mildew.
“Previously, while there were preventative fungicides registered in carrots, none of them had the early curative properties required to combat the established disease.
“Amistar Top combines two active ingredients difenoconazole, which offers the early control of powdery mildew and azoxystrobin, which is an excellent preventative fungicide.”
Syngenta marketing manager Richard Packard says that an additional reason for growers to be on the lookout for the first sign of powdery mildew is because treatment is most effective prior to row closure.
“In summer, particularly, a dense canopy can prevent the fungicide reaching where it needs to treat, and protect, the carrot. Spraying prior to row closure means the crop has the best chance of keeping ahead of the disease,” Richard says.
“We have also developed a range of nozzles to accompany Amistar Top in Carrots, which can help growers to achieve effective coverage of the lower carrot crop canopy and to optimise product performance.
“Hopefully an increase in awareness of the existence of this disease in carrots will mean that growers will strike early and we will see fewer yield losses due to powdery mildew this year.”
For further information on Amistar Top please consult the label, call the Syngenta Technical Product Advice Line on 1800 067 108 or visit our website at www.syngenta.com.au. Syngenta is one of the world's leading companies with more than 26,000 employees in over 90 countries dedicated to the purpose of bringing plant potential to life. Through world-class science, global reach and commitment to customers, Syngenta helps to increase crop productivity, protect the environment and improve health and quality of life. For more information visit www.syngenta.com.au