Protect potato tubers against blight infections from
tuber initiation onwards, warnsGowan
Comerciotechnical director John
Edmonds.
"Once tubers start to form they are at risk from tuber
blight."
Tuber blight is caused by zoospores that are washed down from
foliar disease infections, he explains.
"They then cause infection by germinating near to the tuber and
entering through access points such as buds, lenticels and
wounds.
"The fungus then spreads and starts to break down cellular
tissue.
"You only need a few zoospores to reach potato tubers to suffer
significant and damaging blight infections.
"Symptoms are usually seen within one month of lifting, but the
disease must be prevented in the field well before it gets into
store."
The key is using blight fungicides with zoospore activity, but
they need to be used in the correct way, he says.
Using a product such as Electis (zoxamide) stops formation and
release of zoospores, but this should be followed by fungicides
such as fluazinam, cyazofamid or fluopicolide + propamocarb that
act on released zoospores, says Mr Edmonds.
Don't rely on foliar blight protection alone, particularly when
blight pressure is high, he adds.
"Spray intervals should be kept tight right up to and beyond
desiccation."
