246 
REI'OKT ON ECONOMIC ENTOMOLOGY 
A root fungus 
A rust fungus 
Life-cycle of a 
rust fungus 
Cotton Boot Kot 
A fungus attacking the roots of cotton plants has been noticed on farms in the vicinity 
of Khartoum. It appears to be identical with the cotton root rot fungus (provisionally 
identified by Pamrael as Ozom'uin auricomum, Link) that occurs in the United States. 
I have only seen this disease during the rainy season and on young growing cotton. 
The first signs of an attack of root rot are usually noticeable on a sunny day following 
a downpour of rain. Sometimes isolated plants, at other times whole areas, will Hag and 
wilt as though from want of water. Within three days these plants will probably be dead. 
On examination, the rootlets and the hark of the tap root will be found to be quite rotten, 
and frequently there is a depressed area on the root just below the surface of the soil. 
A spell of dry weather usually stops the spread of this disease. 
F revent ions and remedies .—The fungus being in the soil, the only course open to the 
farmer is to starve it out by growing on the infected land only those crops which are not 
susceptible to its attack. Dura, dura shami, wheat, barley and other cereal crops are said 
to be immune. 
If it is not possible to completely rid the soil of this fungus, cotton should bo included 
in the rotation not oftener than once in three or four years. 
Care should be taken to keep infected land free from weeds. All remains of a 
diseased croj) shoidd be burnt. 
I).\NG.\IL 
A considerable loss to the wheat cro]) is occasioned every year by one of the rust fungi, 
probably Fuccinia gr/niiinis, I’ers., the black or sujniner rust of wheat. 
The native name for this pest is “ Dangail.” 
Fuccinia (jraminis is a well-known pest in Britain, North America, Australia and other 
wheat-growing countries. 
The symptoms of an attack are as follow; The young growing crop, on becoming 
infected, loses its healthy green appearance and becomes yellowish. If the leaves and 
steins are examined, small elongated orange-coloured spots bearing a fine powder will be 
seen. Later on in the season, black lines appear, especially on the stems and leaf sheaths. 
The head of corn is small and the grain frequently so shrivelled as to be practically 
worthless. 
The following is a brief outline of the life-cycle of Fuccinia (jraminis as it occurs in 
England. 
The winter is passed in the teleutospore stage, the teleutospores arising from the black 
longitudinal lines seen on infected straw. These teleutospores, in the spring, give rise to 
smaller spores, known as sporidia, which are blown about by the wind until eventually some 
alight on the wild barberry (Berheris vulgaris, L.). Here they germinate and give rise to 
yellow patches and, later, little flask-shaped depressions on the upper sides of the leaves. 
Within these depressions are produced conidia, whose functions are unknown. Yellow 
patches then appear on the under sides of the leaves, and these give rise to cups, bearing 
lEcidiospores, which escape in July to attack the wheat. Infection takes place through the 
stomata only, and about eight days later orange-coloured uredospores are formed, which are 
Ijorue by the wind from plant to plant, thus rapidly spreading the disease. This spread by 
uredospores continues until the host plant has reached maturity, when the thicker walled 
teleutospores are produced, as being better suited for hibernation. 
