Growers have faced a start choice when it comes to managing potatoes this season – often having to choose between keeping the crop alive with water or making a more challenging strategic decision.
Even crops grown in the perfect silt that were planted in great conditions are struggling under the prolonged hot and dry weather, says Hutchinsons root crop technical manager Darryl Shailes. So too have some irrigated crops, he adds.
During the July heat wave, many crops ceased bulking and only put on dry matter, and were just about kept alive. By early August, most irrigation reservoirs were getting very low, with restrictions are being put on some other licences.
“This rapid increase in dry matter means that many crops especially those that are unirrigated or short of water are already in excess of 24% dry matter and will be highly prone to bruising,” says Mr Shailes.
The best decision for many growers was to stop the crop – even though this would mean low yields.
“To leave the haulm alive under the current conditions will only increase dry matter and yield is unlikely to be significantly improved.
“For some crops even if rain were forecast, their ability to increase yield and tuber size significantly will already be compromised with very poor haulm and will probably cause issues with secondary growth. “
Growers may have to target lifting and irrigation to crops most sensitive to bruising. Where water is available, pre-harvest irrigation can help keep more soil on the web and cushion potatoes to reduce bruising – despite having no real effect on dry matter.
“Single handling and correct settings of harvesters and elevators will be even more important than normal to reduce the exposure to bruising as much as possible,” says Mr Shailes.
“A relatively small unbruised crop should be easier to market than a slightly larger but heavily bruised crop.”
But it isn’t all doom and gloom. “Some well irrigated crops are still bulking and have good haulm and in an ideal world soil moisture deficit should be maintained at around 30mm until flailing and or burn down to reduce the risk of bruising.”
“Normally blight control would need to be continued until all the haulm is dead but with this season with hardly any reports of blight some growers may decide not to treat during the haulm destruction process especially on crop not intended for storage.”