Smut

 

 

Apart from flag smut, smuts are not easily diagnosed until head emergence. Infected heads emerge and grains are replaced by masses of dark brown to black spores. Depending on the type of smut, spores are either held loosely (loose smut) or tightly (covered smut) in the head. In contrast, flag smut symptoms appear on the leaves rather than the head. Lesions on the leaves contain masses of spores which break through the tissue as the plant matures. Plants may be stunted, leaves curl up and appear distorted and affected tillers often won’t produce grain.

 

Smut diseases can either be internally seed-borne or externally seed-borne. Spores of internally seed-borne smut (i.e. loose smut wheat/barley) survive within the seed, where it remains dormant until planted. Once planted, the fungus grows within the plant undetected until infected heads appear. Spores of externally seed-borne smut (i.e. loose smut oats) survive either in the soil or externally on the grain and can also found as contaminants on machinery. Spores remain dormant over summer, germinating under moist, cool conditions to infect emerging seedlings before finally producing smutted heads or leaves. 

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Control of smuts focuses on prevention and reducing inoculum levels. Once an outbreak of smut has been diagnosed, clean seed should be sourced for planting.  Growers should avoid planting susceptible varieties and if possible, opt for varieties with some resistance.

 

Generally, smuts are effectively controlled through the regular use of fungicidal seed treatments.  Some seed treatments can be applied in-furrow, which can sometimes provide less effective control compared to seed applications. For a seed treatment to be fully effective it is essential that seed is evenly covered.

 

Jockey^® Stayer^®, EverGo^® Prime, EverGol^® Energy, Raxil^® T and Hombre^® Ultra can be used to control smuts in cereals. Jockey is registered for the control of flag smut (seed and soil-borne) in wheat, loose smut in barley and wheat, covered smut in barley and wheat (often referred to as common bunt). EverGol Prime is registered for the control of seed-borne flag smut (suppression of soil-borne) in wheat, loose smut in barley, wheat and oats and covered smut in wheat (common bunt), barley and oats. EverGol Energy is registered for the control of flag smut (seed and soil-borne) in wheat, loose smut in wheat, barley, triticale and oats, and covered smut in barley and covered smut (common bunt) in wheat. Raxil T and Hombre Ultra are both registered for the control of flag smut (seed and soil-borne) in wheat, loose smut in wheat, barley and oats and covered smut in wheat (common bunt), barley and oats.  

 

CropPro (Viewed Nov 2019), ‘Covered smut of barley’, http://www.croppro.com.au/crop_disease_manual/ch04s06.php