A GROWER’s best defence when it comes to controlling the damaging chickpea disease phytophthora root rot (PRR) is forward planning.
NSW DPI research officer Sean Bithell said the soil and water-borne disease can establish permanently in a paddock and fungicide treatment was expensive and ineffective in providing long-season control.
That leaves growers with only one management option – careful pre-plant planning with paddock and variety selection, he said.
GRDC has released an informational video, aimed at equipping growers with the tools to identify the disease, reduce the risk of it occurring and prevent on-going paddock and crop infection.
Mr Bithell hosts the instructional video and offers expert advice on how the disease survives, expresses in crops and responds to certain environmental conditions.
“If we find PRR in the field it is actually too late, we can’t do anything about it in terms of applying a protectant but there are actions we can take to get a handle on the extent of the infection and an estimate of how that’s going to affect our yield,” he said.
“If it’s really early in the season and there’s plants dying at the two or three leaf stage, you can expect a wipeout in the areas you can see it. If it’s happening at the end of the season and the plants have already flowered and are at pod fill, the impact on yield could be quite minor.
“Then it becomes a choice of how you deal with that paddock – for a widespread early infection some people may decide to spray out the whole paddock but if it’s a later infection, they may opt not to harvest the infected area and clean up the weedy hosts which are associated with PRR.”
Within the video Mr Bithell explains that effective long term planning and paddock management hold the key to keeping the PRR risk at bay.
“It’s about knowledge of your paddock history – have you had PRR present in the past, are there areas of medic weeds?” he said
“From there it can be managed with good pre-planting decisions—planting into low risk paddocks, sowing the most resistant variety available if sowing into a medium or high risk paddock – and effective weed management within break crops.”
With its ability to survive and spread via water, PRR infection is greatest in wetter than normal seasons, as occurred in 2010, or during periods of soil saturation in normal seasons, as occurred in the early part of 2012. Only one saturating rain event is needed for infection.
The most effective control strategy is to avoid planting chickpea into high-risk paddocks, which are those with a history of PRR in previous chickpea or lucerne crops, lucerne or medics (annual or perennial), or waterlogging, although the conditions that induce waterlogging may not occur every year.