Heavy rains send soybeans rusty
THE Tweed has been so wet from constant rain the crops are going rusty.
Soybeans which have become an increasingly-important cash crops for canegrowers as well as helping cane crops by pumping nitrogen into the soil are going rusty in the rain.
An outbreak of leaf rust disease is threatening this year's bumper soybean crop, due to be harvested within weeks.
Condong canegrower David Bartlett yesterday was busy checking his crop for any signs of the disease following a call from the NSW Department of Primary Industries for farmers to get into the fields and check the leaves.
With 13,000 hectares of soybeans planted between Macksville and Tweed Heads and a near record 36,000 tonne crop waiting to finish off, growers are being advised to monitor their crops and treat if necessary and possible.
Mr Bartlett however said that could be difficult.
“We are in a fairly built-up area now which restricts aerial spraying,” he said.
“Sunshine would definitely help.”
Grafton-based research agronomist Natalie Moore said the current cool, rainy weather was favourable for rust growth, which was a concern with harvest so close.
“Rust can develop rapidly during showery weather, causing leaf drop and significant yield losses,” Dr Moore said.
“If left unchecked and with favourable conditions, the rust can prematurely defoliate the soybean plants and significantly reduce seed size and tonnage.”
“Growers need to protect the green leaf on the plant now, especially in the late-planted crops where the pods have not yet finished filling.”
Mr Bartlett said soybeans were becoming a cash crop for many Tweed farmers.
“Before it was just an experiment to se if they would grow,” he said.
“Now we are finding out they have advantages for nitrogen fixation for the next cane crop.
“We are using them as part of best farming practice. They are an important part of our cropping cycle.”
Dr Moore said growers were looking towards a good harvest after last year's crop was hit by flooding rains then leaf rust, particularly south of the Tweed.
“Some crops were set back this season due to the hot dry conditions in January and late planting - so there is a fair bit riding on this harvest,” she added.
“If crops have five weeks to run and the current wet conditions continue, growers need to protect the green leaf with a rust treatment as soon as they can get back on their paddocks.”
She said the department was making a new permit available for a special chemical, Folicur 430 SC, for use against leaf rust in soybean and growers should discuss treatment with a departmental agronomist or their rural supplier.