Breeders rethink field pea varieties

Haidee VandenbergheCountryman

An innovative system recently rolled out by the Department of Agriculture and Food could change the way breeders are looking at future varieties of field peas.

In 2004, department systems analyst Moin Salam rolled out the first online planting guide to minimise the risk for field pea's biggest woe, Ascochyta blight.

Dr Salam's research shows that over the past decade, growers have suffered average yield losses of around 57 per cent just from Ascochyta blight alone.

The main issue is that stubble-borne spores from the previous year's field pea crop travel by wind to infect the current crop.

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"We found that with one gram of stubble we had more than 55,000 spores, just in one single batch," Dr Salam said.

"And it comes batch after batch within a season."

Initially plant pathologists suggested chemical control could be the way to tackle the disease, but it would take at least seven or eight sprays to manage it.

However, that approach only proved to be economical if the peas were yielding more than two tonnes and so Dr Salam set his sights on whether timing could, in fact, be the key.

"An agronomist came up with a brilliant idea - due to their experience in the field they found that most of the spores came during the break of the season or immediately after," Dr Salam said.

"What they found is that if growers waited two to three weeks after the break, that was the best time to sow the crop and manage the disease.

"That was good but if you delay the crop you lose potential yield."

Yield loss risk and optimum sowing time for disease management were then combined into an online tool to give growers the best chance of minimising both and maximising returns.

In 2004, the first online sowing guide was rolled out for field pea growers in Scaddan using year-to-date weather information and projected rainfall events.

"We also considered other constraints like frost and the effect of late sowing," Dr Salam said.

The following year the guide covered the whole of WA and last year this information was sent via SMS to about 60 growers in the Esperance area.

"We have a dedicated website and we update this information every week during April and May and put it on the web," Dr Salam said.

"We have done a simple economic analysis in the Esperance area and during 2003-2010, based on the disease, we calculated the yield loss.

"(If growers sowed immediately) after the break of the season, then that would cost them 546kg/ha.

"In some years it's very high and some years it's very low, but if they follow our recommendation, which is a compromise between agronomic yield loss and disease yield loss, the can save on an average 160kg/ha."

Analysis found that since the department has started offering the field pea time of sowing advice, productivity in the Esperance area has almost doubled and the number of field pea growers has increased 18 fold.

The project has proven so successful that it was launched interstate, with South Australia receiving the guide two years ago and Victoria and New South Wales last year.

This season those states will also receive the information via SMS and more than 2000 growers across Australia have already signed up.

Dr Salam believes it is the only model in the world that can be applied in the field to solve farmers' problems.

The model is also gaining international attention, with Dr Salam picking recognition while addressing a conference at Amity University in New Delhi, India.

However, the research on time of sowing and Ascochyta blight is nowhere near finished.

Significantly, the model developed by the department's team also has implications future breeding directions in the light of climate change.

Scientists predict there will be more summer rain and less spring rain in the future and when that information is correlated to the risk of Ascochyta blight, Dr Salam said breeders may need to rethink which traits they are targeting.

"Disease pressure will be low but yield might be affected because of less spring rain," he said.

"What we are proposing now, is breeders… concentrate on shorter duration varieties rather than working on disease resistance."

Growers also have ideas about how they would like the time of sowing model to develop. "This prediction is a regional prediction, but (growers) want a paddock by paddock situation," Dr Salam said.

"When you visit the field you will see in some paddocks they have more disease than others, which will be affected by the proximity of last year's crop, wind direction and the disease status of last year's crop.

"We are thinking the third generation model will be paddock specific, which is difficult but if the growers can put the information in, we can find a solution.

"SA Research and Development Institute is working closely with usand are doing field studies.

"They conducted a two year experiment on the paddock specific situation and we will be analysing this data to see if can give a paddock specific warning."

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