Vol. XXXI. Part 4. APRIL 3, 1920. 



Agricultural Gazette of New South Wales. 



An Obscure Disease in Wheat* 



J. T. PRIDHAM, Plant Breeder. 



For many years we have noticed at Cowra and in other districts a condition 

 in wheat crops which appears to be one of disease, though its specific nature 

 has not yet been discovered. Specimens sent to Dr. Darnell-Smith showed 

 spores of Erysiphe fungus but no signs of take-all. While the writer was 

 resident in Victoria some years ago, specimens of this trouble were sent 

 to Mr. McAlpine, who found no fungus of take-all present, and considered 

 that the condition was due to an unfavourable state of the soil, physical or 

 chemical. 



Nothing abnormal is seen in the wheat plant until it is out in head, and 

 the grain starting to form. As the straw and ear turn from green to the 

 ripe state, some stalks have thin flat-sided ears, which have a faded, Hull 

 appearance, instead of the bright-tinted, bold condition of normal heads. 

 When ripe, the grain is very thin and pinched ; in extreme cases no grain 

 ie formed, but in these cases the head is not bleached white as in take-all, 

 nor is there the blackening at the foot of the straw. Farmers have come 

 to consider a proportion of such heads quite the usual thing, and variously 

 attribute the condition to insects, frost, want of moisture, or bad patches of 

 soil causing malnutrition. Each of these suggested causes has been con- 

 sidered, but each fails when tested. Last season white ants attacked the 

 roots of the wheat, but we had not found them in previous years, and at 

 Cowra no other insects have caused damage of this nature so far as we 

 know. 



The trouble has occurred in mild seasons with no severe frosts ; and it has 

 been found in outside plots bordering a path where the growth of adjacent 

 healthy plants was more vigorous than usual, so that want of moisture and 

 nourishment cannot be entertained as the cause. We have sown pinched 

 grain from affected ears and have obtained a healthy plant bearing good 

 grain, the seed not having been pickled or treated in any way. Observations 

 for the last nine years at Cowra may be summarised thus : — 



1911. — The prevalence of an obscure disease like take-all was noted. 



1912. — A sprinkling of plants affected with this disease was found all 

 through the plots. Some plants produced no gi-ain, others were only partially 

 affected. 



1913. — In this year all the seed for the stud plots was treated with blue- 

 stone and limewater before sowing. In spite of this there Was a large 

 percentage of diseased plants throughout the plots. 



1914. — The disease occurred in patches and was worst in loamy free- 

 working soil ; there was very little indeed on stiff red clay. All stages were 



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