ENCLOSURE TO PART IV. 
Dysdercus spp. have been credited with several different forms of 
injury, one of which, namely direct staining of the lint with their 
excreta, is not now held to be of serious importance by any 
investigator: there remain: — 
1) Transmission of Internal Boll Diseases; 
(2, Causing shedding of young bolls without the intervention of 
disease; 
3) Inducing failure of the bolls to open normally; 
(4) Injury to the young seeds resulting in failure of lint to 
develop normally. 
(5) Injury to seeds affecting germination and impairing their 
commercial value for crushing. 
Of the above the first would appear to be the most important. 
Internal boll diseases, including lint staining, are prevalent in this 
Colony and if Dysdercus spp. is to be regarded, as the main cause 
these insects must clearly be accorded a very prominent place amongst 
cotton pests. Other sucking insects large enough to pierce the carpels 
are more or less negligible in numbers in comparison. 
In carrying out investigations into the question of the trans- 
mission of disease by insects, it is obviously helpful if an accurate 
method of identifying the disease is known. In the present instance, 
however, there appears to be some degree of uncertainty in this 
connection. 
It would appear first of all that one form of boll rot may be 
separated at once from the others, namely that caused by Bacillus 
malvacearum which has been shown definitely to be independent of 
extraneous aid in obtaining entrance to the interior of the bolls. 
"* Soft Rot * caused by a species of Phytophthora would also appear 
to be a specific and readily recognised disease (Nowell). 
In Southern Rhodesia Mr. F. E. Eyles, Botanist and Myecologist, 
Agricultural Department, records the following of bacteria and fungi, 
which have been associated with boll rot elsewhere, namely: 
Pseudomonas malvacearum, Smith; Bacillus gossypii, Stedman; and 
Colletotrichum gossypii, Sout. (Rhodesia Agricultural Journal, June 
1926, p. 637). Of these B. gossypii, Stedman, has been found in 
association with Bolirot, and Colletotrichum with compaction and 
discolouration of lint in Southern Rhodesia. 
The careful experiments carried out by Nowell in the West Indies, 
Pomeroy and Golding in S. Nigeria, and Ballard and Holdaway in 
Queensland, although implicating Dysdercus and other sucking insects 
in the transmission of bollrot, afford comparatively little enlightenment 
as to the specific organisms causing the disease. Marsh, however, 
appears to have associated lint staining in Nyasaland tentatively with 
Nematospora sp. A fungus of this genus was also isolated by Nowell 
in the West Indies and he mentions that Bartlett apparently isolated 
a similar fungus. Ballard and Holdaway, however, do not mention 
this genus amongst the fungi bred from samples of cotton in Queens- 
land. In point of fact, the only genus of fungi associated with 
“ Bollrot ’’ in all countries, where these have been really studied, 
seems to be Alternaria. 
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