Analyzing The Causes Of A Poor Start For Cereals

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LETHBRIDGE

Some of the reasons for last spring’s poor start to cereal crop growth can be mitigated or avoided in the future, says an industry agronomist. “We started off with some challenges but the end result was fantastic,” said Keith Mills, manager of agronomic services for Viterra in southern Alberta.

Mills told participants of Agronomy Update 2009 here in January that despite the slower early-season growth and weaker vigour in some areas, most of the fields recovered to produce an above-average yield. Some never fully recovered though.

“The first step is to identify the problem and its cause, and secondly, determine if we can prevent, reduce, eliminate or live with it in the future,” said Mills. “While no year is ever the same as another, we need to know the contributing factors so we can manage moving forward.”

Mills says poor crop vigour can be defined as anything less than expected for crop development in the spring. Symptoms of poor vigour on mostly dry-land fields in southern Alberta for 2008 were often described as “the crop was sick-looking, stunted, leaves were thin, the stand was thinner than usual, and there was slightly yellowish and/or purple colouration to the leaves,” said Mills.

In his synopsis of potential contributing causes, Mills said in his experience most of the problem fields were seeded early in the spring from March 20 to May 1. As last spring was cool and wet, with a week of sub-zero temperatures and heavy snow at the end of April, many fields seeded in early April did not emerge until the beginning of May.

That said, early seeding was not the only contributing factor since many early-seeded fields showed excellent vigour after they emerged. “Very seldom is there just one cause of a field problem,” said Mills.

He also noted that seed was harvested in 2007 under very hot and dry conditions. “Seed produced in difficult conditions can have more challenges coming up in cold, wet conditions.” Many of the cereal fields that showed delayed growth also had symptoms of seeding blight and shredding and physical damage of the stem and roots just below ground level.

The damage is typical of wireworm feeding. Wireworms are copper-brown, cylindrical, hard-bodied insect larvae that feed near the soil surface when the soil is cooler and at deeper depths when the soil warms. Typically, this limits the damage caused by wireworms to a short period of time in the spring, unless, like last year, the temperatures stay cool.

Some of the adverse affects can be mitigated by seeding shallower into warmer soil, which means seeding later. However, one of the advantages of southern Alberta is the ability to seed early. Other ways to mitigate the concerns include seed treatments, seeding as shallow to moisture as possible and increasing the seeding rate.

Another explanation of the problems seen in 2008 is herbicide residue carried over from the 2007 hot, dry fall harvest of broad-leafed crops, said Mills. Common symptoms included yellow or purple striping and stunting.

One final factor, according to Mills, is that sometimes cereals and flax following canola can perform very poorly at the beginning of the year. “In the end, we just have to manage what we can,” said Mills. “Don’t seed everything on one day – spread out the risk.”

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