Diseases of Wheat - Non-Infectious

 
 
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 Copper deficiency (Melanosis) | Cold soil | Heat branding | Frost damage | Winter kill

Copper Deficiency (Melanosis)
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What to look for?
Pseudomonas cichorii, a bacterium, was once thought to be the cause of a disease called melanosis and severe yield losses in wheat. We now know that this bacterial infection is secondary to the primary cause namely severe copper deficiency.

Severe copper deficiency may also show up in barley, rarely in oats and never, to our knowledge, in rye or triticale. Rye, triticale and most oat varieties are efficient at removing copper from the soil. All wheat and most barley cultivars are highly inefficient at copper up-take from soil.

Severe copper deficiency causes lodging and white heads in both winter and spring wheats. Copper is essential for lignin formation in cereals such as wheat and barley. A deficiency is a frequent cause of unexplained and severe lodging.

The shriveled grain and presence of ergots in the harvested wheat is highly diagnostic of copper deficiency. Soil moisture, fertility management, addition of livestock manure, foliar herbicide, soil type and growing season all influence the degree of yield loss due to copper deficiency.

Copper deficiency causes pollen sterility in wheat, barley and occasionally oats. Pollen sterility causes the normally closed florets to open exposing the female stigmas to ergot infection. Rye and to some extend triticale are open pollenated and stigmas in rye are consequently exposed to ergot infection.

Huge irregular (brown) patches of copper deficiency occur particularly on sandy soils. In black peat, on fen soils of which there are around 100,000 acres in Alberta, complete crop failure may occur unless soil or foliar copper, or both are applied to the wheat or barley (see copper deficiency in barley) crop.

Up to 40% of Alberta soils and perhaps up to 4% of the Canadian Prairie soils are low to deficient in copper fertility. Half of the soils 51 - 20% could be classified as severely copper deficient for wheat and barley production. Adequate copper fertility to Alberta cropland has been calculated to be worth 30 - 40 million dollars annually to the wheat crop alone. Copper fertilizer sales rank in the millions annually and are by far the highest in Alberta of the three prairie provinces.

In sandy or peaty loam soils under high fertility regimes wheat yields have been doubled and even tripled with amended copper fertility.

Severe melanosis in Park wheat
Photo: Piening
Picture description
Severe melanosis in Park wheat
Shrivelled or frosted grain.
Melanotic to healthy wheat in same field showing field variations in copper availability.
Photo: Evans
Picture description
Melanotic to healthy wheat in same field showing field variations in copper availability.
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Sterile empty head of wheat due to severe copper deficiency.
Photo: Evans
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Picture description
Sterile empty head of wheat due to severe copper deficiency.
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A: Inadequate copper fertility resulting in "frosted bran".
Photo: Evans
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Picture description
A: Inadequate copper fertility resulting in "frosted bran".
B: Good grain with adequate copper fertility.
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Large irregular areas of copper deficiency in a wheat field.
Photo: Piening
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Picture description
Large irregular areas of copper deficiency in a wheat field.
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Management strategy
Soil test and when necessary apply adequate soil or foliar copper fertilization to meet the crop needs. See Copper Deficiency: Diagnosis and Correction (Agdex 532-3) for more information on copper deficiency.

A more complete description of copper deficiency in wheat.

Cold Soil

What to look for?
Wheat or barley sown into very cold soil may germinate poorly or fail to emerge as a consequence of low temperatures, likely exasperated by crop applied or residual herbicide, and sometimes as a negative consequence of seed treatment.

Soil residual herbicides or even crop applied herbicides may cause emergence problems in wheat, barley and oats.
Photo: Evans
Picture description
Soil residual herbicides or even crop applied herbicides may cause emergence problems in wheat, barley and oats.

Management strategy
Exercise care when using wild oat herbicides and check the soil If possible via a bioassay for persistent herbicide residues that may be present causing crop loss or crop failure.

Heat Banding

What to look for?
Wheat or other small grain cereals germinating under warm moist soil and bright sunny conditions may show heat banding or rugby stocking disease. This is due to the fact that growth can occur during the night and this (previously unexposed) area of leaf may be damaged by the bright hot sunlight.
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Heat banding or rugby stocking on wheat seedlings.
Photo: Evans
Picture description
Heat banding or rugby stocking on wheat seedlings.
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Management strategy
None.

Frost Damage

What to look for?
Frosted bran may well be caused by August frosts that drop to below -2o Celsius in mid- to late-August. However this condition is now, in the absence of recorded frost, known to be primarily due to copper deficiency. Very common in areas of Alberta with light sandy soil such as Lacombe, Parkland and Sturgeon counties.
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Frosted bran caused by copper deficiency.
Photo: Evans
Picture description
Frosted bran caused by copper deficiency.
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Management strategy
Apply copper to the soil or as a timely foliar spray to eliminate this problem. See copper deficiency in wheat or barley.

Winter Kill

What to look for?
In some years when winter wheat is grown under prolonged snow cover, often into April the "greenhouse" effect caused by the sun on the snow will often warm up the soil under this snow cover. This very wet relatively warm condition allows one or more snow mold fungi to kill-off the wheat seedlings. On golf courses, soot or wood ash may be spread on the greens and surrounding areas to speed up snow melting and prevent the development of snow molds. Global soot is considered to be a major player in the global warming effect by preventing reflection of sunlight by the snow cover and causing much more rapid snow melts.

Severe kill of winter wheat by snow mold fungi.
Photo: Evans
Picture description
Severe kill of winter wheat by snow mold fungi.
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Management strategy
There are no control procedures at the present time other than a 3 - 4 year crop rotation.

A more complete description of winter kill or winter damage in wheat.

Photographs and information assembled and prepared for ARD by Dr. Ieaun R. Evans Agri-Trend Agrology Ltd.
 
 
 
 

Other Documents in the Series

 
  Diseases of Wheat - Fungal
Diseases of Wheat - Non-Infectious - Current Document
Diseases of Wheat - Viral
 
 
 
 
For more information about the content of this document, contact Ron Howard.
This document is maintained by Shelley Barkley.
This information published to the web on December 8, 2003.
Last Reviewed/Revised on March 14, 2008.