Letters on the Diseases of Flants. 19 



7. "White-heads" or White B%ht of Wheat. 



A disease often spoken of as "white- heads," characterised by the bleached 

 appearance of the full grown wheat plants, and by the absence of grain from 

 the heads, is not infrequently the subject of inquiry by farmers. This 

 disease was treated of in my article on Take-all,* under the special name of 

 " White Blight." Observations and experiments since made confirm the 

 opinion that this disease is one connected more particularly with the soil, 

 though probably some organism is the primary cause. The treatment 

 formerly recommended is still more fully endorsed. 



Apply lime to the diseased patches as a manure, at the rate of about 1 

 ton per acre. In the absence of lime, the ashes obtained in burning off may 

 be utilized with almost equally good effect. 



II. Diseases of the Plum. 

 Disease of the Japanese Plum. 



Numerous varieties of plums, especially Japanese varieties, have been sent 

 to me this season, attacked by a disease about which I have as yet discovered 

 little except that it was undoubtedly serious. The fruit is misshapen, failing 

 to grow, more particularly on one side. The defective side has an irregular 

 and roughened surface, from cracks in which gum sometimes oozes. With 

 the prevalent notion that the disease is " sun-scald," i.e., is due to the heat 

 of the sun, I cannot agree, because as often as not I find the diseased side 

 turned away from the sun. The disease seems to me to be one connected in 

 some way with the wood, and to be perhaps related to the disease known 

 as gumming. I suspect it to be transmitted through grafts. 



Remedies. 



1. If a tree shows the disease very badly for three years in succession 

 either remove it or graft on another variety known to be not subject to the 

 disease. 



2. Do not buy trees except under a guarantee that they are grafted from 

 healthy trees. 



3. Do all you can to spread the information that cuttings taken from 

 diseased trees are likely to produce diseased trees even if grafted on to 

 healthy stocks. 



4. I can hold out little hope that any sort of spraying will be beneficial, 

 but if other trees are being sprayed there would be no harm in trying the 

 effect of Bordeaux mixture on this disease. 



5. According to my observations plums grow to the greatest perfection on 

 limestone soils. This seems to point to the use of manures rich in lime. 

 Potash is also desirable. 



The letters accompanying these specimens of diseased plums have some- 

 times inquired whether the disease is not " Plum Pockets." So far as I 

 know, the disease known by the name of Plum Pockets does not occur in this 

 country. As the name of this latter disease implies, the plums are converted 

 by it into " pockets," that is thoy become hollow and have no stone. I have 

 never seen such objects in Australia, and therefore conclude that they are at 

 least uncommon. 



* Agricultural Gazette of N.S.W., Vol. Ill, p. 991. 



