| Arable
New Amistar approval adds Alternaria protection for potatoes
A new approval for Amistar is set to better protect potato crops from Alternaria that can decimate green leaf area in the summer months .
W ith Amistar foliar treatments targeted specifically at stopping infections of Alternaria solani spp , growers and agronomists now have a season long programme to help prevent pathogen strains from June through to harvest , advised Douglas Dyas , Syngenta Potato Field Technical Manager .
“ Alternaria has been an increasing problem in some recent seasons ,” he reported . “ The increased area of varieties that are more susceptible to infection , combined with prolonged periods of stressful weather conditions , has led to serious outbreaks in some seasons .”
Douglas advocated that Alternaria must be tackled preventatively , in conjunction with the late blight fungicide programme . “ Growers should look to start Alternaria control as soon as conditions are conducive to infection , typically from end of June , but remaining aware of risk factors for any individual crop .”
His recommended programme will incorporate up to three applications of Amistar , aimed at protecting against Alternaria solani , in conjunction with Amphore Plus , utilising its combination of a robust application rate of difenoconazole , to give effective prevention of A . alternata and A . solani , along with its built-in full rate of mandipropamid ( Revus ) for blight control .
“ This approach should be sufficient to offer protection for crops throughout the season ,” he advised . “ Growers will have to add a blight fungicide with their Amistar treatments , such as Revus or Shirlan , depending on previous treatments and within CAA and FRAC guidelines .”
He highlighted that best results will be achieved where growers use fungicide protection in an integrated crop management ( ICM ) programme , including variety selection and aiming to avoid high risk stress factors , such as soil moisture or nutrient stress .
A further change to the Amistar approval in potatoes has seen the removal of the overall treatment of seedbeds pre-planting at 6 l / ha . However the 3 l / ha in-furrow application remains unchanged for Black Dot and Rhizoctonia , to improve skin finish , along with enhanced tuber consistency and quality .
Growers with stocks of old label Amistar can still use it to make the 6 l / ha overall application at planting , with a use up of old label material by the end of August 2018 . Old label Amistar can also be used for the new foliar Alternaria treatment , but a copy of the authorisation letter must be downloaded from the CRD website before use ( www . pesticides . gov . uk ).
www . farmingmonthly . co . uk March 2017 | Farming Monthly | 15