misc i;i.i. widi s CROPS. 615 



cheaper than all others are also the most effective. The grower must, 

 however, first know how to recognise eaclj dista.se and how its spread may be 

 prevented 



riic following notes on the four diseases most common in New South 

 Waifs arc supplied by Mr. I >. S. North, plant pathologist to the Colonial 

 Sugar Refining Company, Limited, who has done valuable work in this 

 sphere. 



Gumming. 



Gumming is most surely detected by the tiny yellow spots of gum which 



ooze out OH to the cut ends of the canes. Tl esc spots quickly appear without 

 treatment in severe eases. but in mild eases suspected canes freshly cut into 

 short Lengths should lie enclos sd in a tight can [e.g., a billy can) to sweat for 

 two or three hours before looking for the gum spots. 



At quite an early stage of gumming, peculiar narrow streaks, spotted with 

 yellow and orange, turning into yellow streaks towards the leaf-tips, appear 

 on so if the older leaves. Special attention should lie given to these leaf- 

 streaks, because frequently they will draw attention to the presence of 

 gumming in an otherwise healthy-looking held of cane. They may even be 

 found before it is possible to detect any gum spots, although these can 

 usually be obtained eventually by choosing and sweating a number of the 

 most likely-looking stalks. 



In advanced stages, numerous signs of ill health appear, including white 

 leaves, dead and dying canes, gum cavities in the stalks near the tops, 

 &C, (fee. 



All of the present approved varieties are likely to be attacked, although 

 they are resistant compared to some grown in the past. Malabar is the 

 most highly resistant, and therefore the safest variety to plant on farms 

 where the disease is present. No immune variety is known. 



Leaf-scald. 



Two distinct phases occur in this disease. In one phase, whole stalks, 

 sometimes whole stools, suddenly wither and die. In the other, white or 

 withered streaks appear in the leaves and all the buds on the stalk sprout - 

 into side shoots ; the leaves sometimes turn partly white, and show a ten- 

 dency to wilt and to wither at the tips. Either one of these phases may 

 occur without the other, or both may appear together in the same stool. 



The peculiar streaks in the leaves provide the oest symptom for its definite 

 recognition. They are usually straight, narrow, even, well defined, whitish 

 streaks, one or several in a leaf, and may either run throughout the entire 

 length of the leaf-blade and leaf sheath, or only part of this distance. Towards 

 the leaf-tip they sooner or later turn into a withered streak. The discovery 

 of a streak in one single leaf is sufficient to diagnose the disease. 



Where the withering phase occurs alone, sometimes no characteristic 

 symptom indicating leaf scald as the cause of death can he discovered. But 

 frequently peculiar small, sickly shoots (suckers) bearing the typical leaf- 

 streaks may be found by searching at the base of the stool. 



In the other phase, the leaf-streaks may readily be found, both in the 

 ordinary leaves of the stalk and in the leaves of the side-shoots and the 

 small suckers. 



Of present approved varieties, Mahona alone becomes badly affected : 

 N.G. 16 may be attacked in isolated stools, as also may most other varieties, 

 but to still smaller degree. 



