Productive Dual Purpose Winter Wheats

Productive dualpurpose winterwheatsAgnote DPI 438, May 2005Bob Freebairn, Regional DirectorAgriculture, North West New EnglandRegion Region, Gunnedahwww.agric.nsw.gov.auPADDOCK SELECTIONespecially from a grain perspective, require avery high standard of weed control. Otherwisevaluable and often scarce moisture, nutrientsand sunlight are lost to weeds. A high standardof weed control also removes the hazards ofmany diseases.Weed control is a ‘numbers’ game. Managementshould aim to reduce numbers and keep themlow with an ongoing program. The cornerstoneof a good program is to begin weed control inat least the year prior to cropping. For exampleif the paddock is coming from pasture totallyprevent weeds such as ryegrass, from seedingin the spring prior to cropping.Winter wheat is generally sown on the firstlate summer/autumn rain event and there isoften no chance to control winter weeds priorto sowing. Many winter weeds, such as wildoats, annual ryegrass, thistles and mustards alsodon’t normally begin germinating until well intoautumn, long after the crop has been sown.Good weed control over summer is importantto conserve sub soil moisture and can help reducedisease risk. However, summer weed control haslittle impact on winter weed problems.Commonly winter wheat is sown as the firstcrop following a legume pasture phase. Suchpastures (often three to 20 years old) generallycontain high levels of grass weeds. It is importantto remove grasses from the legume pasture midwinter in at least the year prior to cropping towinter wheat.SoilsWinter wheats do well on a wide range ofsoil types. Deep well-drained soils are idealas they maximise the opportunity to store subsoil moisture and allow the crop to explorethe maximum available range of moisture andnutrients, provided there are no toxic sub soilrestraints to root growth. Early sown wheat cropscan root to a depth of two metres, given suitablesoil conditions.Winter wheats can tolerate waterlogging forshort periods, although with reduced production.Some triticales tolerate regular waterloggingbetter than winter wheat and are better suitedto these situations (e.g. poorly drained heavysoil paddocks in high rainfall areas, and wheredrainage is not feasible).Acid soilsGenerally winter wheats perform best wherethe surface and sub-soil pH is 4.7 or higher, andwith little or no soluble aluminium. However, insome districts acid-tolerant varieties can be grownwith reasonable success on soils with pH in thetop 10 cm down to 4.5, but almost certainly withsome yield penalty.Early sown winter wheats often perform wellwhere surface soil (0–10 cm depth) acidity wouldnormally be a potential problem (e.g. below pH4.7), but where soil below 10 cm is non acid(low to no aluminium toxicity). Early sowinggenerally results in fast germination and rootscan grow relatively quickly into the non-acidlower soil layers. Wheat varieties vary widely intheir tolerance of low pH and aluminium toxicity(see Table 2).Herbicide withholding periods(before grazing)When planning herbicide weed control programsit is important to check stock withholding period.Some products have a withholding period(before stock can graze the paddock followingapplication) as long as 70 days. Fortunately thereoften are good alternatives with short withholdingperiods for many weed problems.WEED CONTROLProductive crops, both from a grazing and1

SOWING TIMESTORING SUB-SOIL MOISTUREIf winter wheat is to achieve high winter drymatterproduction, followed by good grain recovery, itmust be sown early. Later sowing results in slowgrowth, poor total winter production, althoughgrain recovery can still be very good.Growth rates from early sowing can be ashigh as 100 kg/ha/DM/day in mid/late autumnwhen soil moisture is adequate and temperaturesare mild. Growth through to the end of grazingtypically average 30–60 kg/ha/DM/day, fromearly sowing, given good moisture, high soilfertility, and sound management. Often pasturesat that time of the year grow at 5–10 kg/ha/DM/day. In contrast growth rates from late sowing(e.g. late autumn) are typically 10–20 kg/ha/day(drymatter basis) and even as low as 1.0 kg/ha/day in colder areas. Early sowing can result inrunning 20–30 dry sheep equivalent per hectarefor around three months.How early to sow depends on the localenvironment. On the inner slopes the best timeto sow is generally late February through March.If conditions are too hot, germination can bepoor and early growth adversely affected. Forany district the early sowing window generallyextends for four to six weeks. The inferencecould wrongly be that such a period gives a fairamount of sowing time flexibility.Stored sub-soil moisture is important to increasethe probability of successful early sowing andwinter wheat survival should a dry autumnfollow. The less reliable opening rains are,the more important it is to conserve sub-soilmoisture during the fallow period. Some soilsare capable of storing more soil moisture thanothers. Choosing paddocks with soils with goodmoisture storage capacity, and ensuring they arefilled to at least a reasonable level, is importantin ensuring a high reliability of winter forage andgrain production.Loamy deep soils are ideal winter wheatpaddocks. They can store up to 200 mm ofavailable moisture per metre of soil depth. Everymillimetre of stored moisture can be worth 10to 20 kg/ha of forage DM or/and grain. Storedsoil moisture of 150 mm can therefore be worthan additional 3000 kg/ha of DM production,especially in a dry year. Stored moisture canalso be vital to grain recovery and thereforegrain yield.CHOOSING VARIETIESVarieties are chosen on a number of characteristicsincluding climate (rainfall, elevation, temperature),maturity, soil type (especially acidity), grainquality, tolerance to diseases and climate risks(e.g. pre harvest sprouting tolerance of grain),straw strength, head type (bearded, nonbearded), and grazing and grain yield ability.No variety exhibits all the desirable attributesand choice depends on balancing the variousrisk factors. Some important factors to considerwhen choosing a variety include;TIMING OPPORTUNITIESMost areas commonly experience low and erraticrainfall through the desirable sowing time forwinter wheats. It is therefore very important tobe ready to sow on the first suitable opportunity(i.e. the first feasible rain event) within thedesirable sowing ‘window’. A missed opportunityto sow in more years than not, results in a missedopportunity of plentiful winter feed from the dualpurpose winter wheat crop.MaturityVarieties with later maturity and a longer coldrequirement are more suited to areas with longercold winters (e.g. Monaro). Varieties with quickermaturity and a lower cold requirement haveTable 1. Suggested sowing times for dual purpose grazing and grain (slopes)February1 2 3 4March April1 2 3 4WeeksVarietyMarombi *Rudd, Mackellar, Dennis, *BrennanWylah, Whistler, Sunsoft 98, *Currawong, M5880, Rosella,Pardolate, Lorikeet, Thornbill earlier than ideal but acceptable if conditions not too hot* optimum sowing time later than ideal, but acceptable212 3 4***** * * ******

Rosella. While Rosella has been a good varietyfor a long time, Sunsoft 98 provides improvedstem rust resistance and similar yield ability. Itis important to investigate market opportunitiesbefore growing varieties like Sunsoft 98 or Rosella(in some years a premium is paid to contractedgrowers).Marombi has more winter habit than the earlymid season varieties such as Wylah and Whistler,but less than Brennan, Dennis, Mackellar, andRudd. It suits slopes/inner plains districts andhas out-yielded in grain recovery the quickermaturing varieties at several assessment sites.It has good straw strength and is a hard wheatwith ASW milling quality. Grazing and grainyields in slopes environments have been veryimpressive.Sunsoft 98 * is a stem rust resistant Rosella typesuited to the slopes.Tennant * is suited to the longer seasontableland areas. It is the latest maturing currentlyavailable variety.Tennant is the only slower maturing varietywith adequate stem rust resistance.Thornbill * has maturity similar to Rosella, butstem rust resistance is improved.Whistler * is the quickest of the winter wheats,often being a few days faster heading thanPardalote, Rosella, Sunsoft 98, Thornbill, orWylah. It has a relatively low ‘cold requirement’and has a tendency to begin heading a littleprematurely when sown early as a dual-purposecrop.Wylah * is Australian hard (AH) quality. Similaragronomically to Whistler and Sunsoft 98. It isperforming well as a useful dual-purpose wheaton the slopes. Straw strength is reasonable togood. It is also a good variety for grain onlysowing from around mid April til the end of May.It has useful tolerance to acid soils.been released for warmer and lower elevatedareas (e.g. slopes districts). A range of varietiesbetween the two contrasting slower and quickermaturing types is available. These tend to bestsuit the lower tableland/inner slopes areas.Wet weather tolerance of grainRed wheats generally have inherent superiorgrain tolerance to wet weather occurring betweenwhen crops are ripe and harvest.Bearded verse non-beardedBeing non-bearded is advantageous in a dryspring or drought year when crops are grazedout rather than taken through to grain harvest.If a crop is frosted in spring at the head stagenon-bearded crops are more suitable should itbe fed off or cut for hay or silage. Non-beardedwinter wheats are popular as hay wheats.Other variety featuresMany variety attributes help determine which onebest suits a given environment. For example inmany upper slopes and tableland areas barleyyellow dwarf virus can be devastating. Varietieswith tolerance and resistance are being releasedto overcome this disease. There is considerablevariety variability to factors such as soil acidity,grain quality, herbicide tolerance, and relativeperformance.Brennan * is suited to a wide range ofenvironments including the lower tablelandsand the inner slopes. It tends to head 10–15 daysearlier than Tennant. It is strong strawed and ofmedium height.Dennis * suits the same growing area andsowing time as Brennan. It is of medium height.In some areas its grain yield has been better thanBrennan. While sometimes early grazing is slowerthan Brennan total seasonal grazing productionis generally similar.Mackellar * is the first barley yellow dwarf virus(BYDV) resistant winter wheat to be released. Itsuits the same growing area and sowing time asDennis and Brennan.Lorikeet * is a Rosella replacement withimproved stem rust resistance.Wedgetail * is the only as yet developedsouthern NSW Prime Hard quality winter wheat.It is bearded with good acid soil tolerance andgood tolerance to Septoria tritici blotch.Pardalote * has very good tolerance to acidsoils. Its grain yield is similar to Rosella.Rudd * is a medium height variety with verygood resistance to Septoria tritici, yellow leafspot, as well as the three rusts. It has goodtolerance to barley yellow dwarf virus (BYDV)and strong straw.SOWING RATEHigher sowing rates generally increase drymatterproduction, especially in early grazing, generallythe first six to 14 weeks after sowing. High sowingrates normally have no negative effect on grainyield or quality.Suggested sowing rates range from 100 to120 kg/ha (220 to 240 plants square metre) forcolder and higher rainfall areas, 90 kg/ha (160plants square metre) for medium rainfall areasand milder environments, and 60 kg/ha (120plants square metre) for lower rainfall warmerdistricts. These rates are based on good qualityseed with a high germination percentage, and anestablishment of 80 percent of seed sown.* indicates a variety protected by Plant Breeder’s Rights3