Ground Cover North : Ground Cover 047 November-December 2003 - North
By Dr COLIN R. WELLINGS* and Professor ROBERT F. PARK, University of Sydney Plant Breeding Institute Cobbitty A major and continuing challenge for Australian cereal breeders is ensuring that new cultivars have adequate resistance to diseases that occur in the different cereal growing regions. While these efforts have met with considerable success, we should also consider our preparedness to meet the challenge of those diseases not yet present in Australia in case they do manage to get here. There are two rust diseases of cereals that pose considerable threats in this context: stripe rust of barley and leaf rust of durum wheat. This article provides some background on stripe rust of barley, while leaf rust of durum will be discussed in the next issue of Ground Cover. Stripe rust of barley, caused by Puccinia striiformis hordei, has been a damaging disease in the Americas since it spread there from Europe in 1975. The disease first appeared in Columbia and spread rapidly throughout South America, causing considerable yield loss by 1982. Spread of the disease northwards was slower, with the first report in Mexico in 1990, and in North America (Texas) in 1991. Resistance to stripe rust of barley has become an important objective for regional breeding programs, with useful sources of resistance identified and progressively incor-porated into a range of agronomic types. The barley breeding program at the International Centre for Wheat and Maize Improvement (CIMMYT) in Mexico has taken a lead role in the testing and breeding of stripe rust resistant commercial varieties. The field site based at Toluca, near Mexico City, is situated at 2800 metres above sea level on rich volcanic soils, and provides an ideal climate during the 'wet season' (June-September) for screening for rust diseases. Only a few barleys are affected by wheat stripe rust (present in Australia since 1979). However, the occurrence and significance of Puccinia striiformis hordei in the Americas resulted in a plan to test Australian barleys at CIMMYT. The initial data collected caused concern: more than 80 percent of current varieties were very susceptible. This information became the basis for testing larger breeding and mapping populations from Australian barley programs, in an attempt to identify resistance in genotypes adapted to our regional conditions. Funding from GRDC provided the opportunity to establish annual disease screening nurseries at Toluca. These nurseries have operated over the past four seasons. The results to date indicate that useful sources of resistance in Australian breeding populations can be selected at the Toluca site. Data is now flowing back to barley breeders who have the opportunity to advance material to commercial release with resistance to Puccinia striiformis hordei. With a commitment to ongoing testing off-shore, it is anticipated that our commercial barley industry will be afforded protection from stripe rust, given the real possibility that this disease is introduced to Australia at some stage in the future. *Dr Wellings is on secondment from NSW Agriculture. FEATURES 24 NOVEMBER 2003 CEREAL RUSTS PA is all about $/ha benefits But there are plenty of hurdles to jump By DAVID EAST Precision agriculture is about better managing inputs and resources to maximise a farm's cropping and profit potential. It is about knowing which paddocks, or areas in a paddock, will respond to increased inputs, and which areas make better sense, economically, to leave alone. Precision agriculture -- or PA as the growing army of supporters now call it -- is a method for tackling the wide variability in yields that occur in most cropping situations, and managing this variability to maximise gross margins. Precision farming replaces the standard practice of treating whole paddocks, or even whole farms, the same.The need for PA is increased as farmers confront two overriding pressures -- the need to increase profitability to remain viable, and an increasing environmental imperative for better and more advanced land management systems. Developed during the late 1980s, the uptake rate of the technology has been increasing every year, and while it seems most farmers do not need convincing that, as a system, it works, there is still a lot of confusion about adopting it. The financial outlay is probably the main issue that most farmers need to be convinced is worthwhile. Distributors and resellers of precision farming equipment, both mechanical and electronic, report that the first question usually asked relates to cost, rather than benefits. Initially, precision farming practices centred around the accurate placement of seed and fertiliser in the soil. Guidance systems to eliminate costly waste and/or duplication because of overlap and/or underlap in applying inputs became the latest 'must have' wizardry. At a recent PA symposium in Adelaide, one grower told his audience that before fitting his tractor with a guidance system, he spent 90 percent of his driving time during seeding sitting at 90 degrees to his heading, looking back at the seeding machine, trying to keep on the straight and narrow. Now, he sits comfortably, without a crick neck, knowing he is working accurately. The added accuracy reduced the number of hectares actually worked in one paddock from 112 to 103, and in another paddock from 185 to 172. He also reported that since installing his guidance system he was saving close to $35/ha in fertiliser costs alone. But accurate tractor driving is only part of the precision agriculture equation. Knowing how much input is required in different parts of the paddock to produce an optimum result (return) is just as important. Enter, then, the world of yield and soil mapping. It is one thing to plant the seed and fertiliser accurately and apply the right amount of chemical spray. It is another to know where to apply it for the best result. It is, unfortunately, in this area, where much of the confusion about precision agriculture lies. Precision agriculture actually requires a grower to take on board a range of new concepts and methods -- the identification of soil management zones, weed and yield mapping, variable input application rates, the use of global positioning for auto-steering and row spacings, through to (in some cases) controlled traffic farming and/or raised bed cropping systems. Addressing the Adelaide PA symposium, Southern Precision Agriculture Association (SPAA) president Malcolm Sargent said for the uptake of PA to quicken among farmers the industry needs better skills, uniform standards, improved linkages between all the players and more software compatibility. "We need standards for equipment design, future software development and map coding so that we all understand what we are trying to achieve," he said. "Too many important maps are lost in office drawers because they are too difficult to interpret." Speaking at the same symposium, the GRDC's Strategic Investment Priority (SIP- 09) program coordinator, Dr Phil Price, actually warned farmers about getting too hung-up on the technology: "PA is not just about technology, it is also about agronomy and, perhaps to bring it all together initially, we need a little more agronomy and a little less technology," he said. The battleground: Professor Robert Park and Dr Colin Wellings visiting field trials with Dr Ravi Singh, CIMMYT Mexico, in September. Above: Barley stripe rust at Toluca, near Mexico City. Meeting the challenge of stripe rust of barley MACHINERY & TECHNOLOGY IN THE NEXT ISSUE Changing to a precision agriculture system of farming generally starts with the introduction of a one-pass (no-till) cropping practice. The capital cost can be horrendous ... or it can be relatively cheap courtesy of the arc welder in the farm workshop. In the next issue of Ground Cover, we will look at some of the on-farm ingenuity that some growers have used to break into no-till cropping practices. Aiding accuracy: guidance systems inside tractors can help eliminate costly waste.
Ground Cover 048 February-March 2004 - North