52 THIN WAD AND TOBAGO BULLETIN. [XVIIL 2.- 



THE RELATION OP ROOT FUNGUS TO PROGHOPPER 

 BLIGHT OF SUGAR-CANE IN TRINIDAD. 



By C. E. Williams, M.A., F.E.S., 

 Entomologist in Charge of Froghopper Investigations. 



There appears (pages 57 to 69) a report by Mr. W. Nowell,. 

 IVIycoIogist to the Imperial Dejiartment of Agriculture for the AVest 

 Indies, on a visit which he paid to Trinidad in December 1918 to 

 February 1919 to study the occurrence of Root Disease of Sugar-cane 

 in this island, particularly in relation to the condition known as " blight" 

 or " Froghopper blight." 



As Mr. Nowell's visit took place owing to my special request to the- 

 Froghopper Committee, I have been asked by Mr. Freeman, Acting 

 Director of Agriculture, to give a short summary of the past views on the 

 causes of the disease, the conclusions that I have come to, and. in 

 general, of the events that led up to Mr. Nowell's visit. 



The present accoimt is by no means complete as there arc a large 

 number of critical and important experiments and observations that I 

 hope to make during the coming season. It will however serve as an 

 introduction to the fuller report that I hojie to give next year at the 

 termination of my engagement. 



HISTORICAL. 



Blight lias been known in Trinidad since the middle of the last 

 century ; at that time, however, critical investigations were seldom 

 made and the damage was more or less vaguely attributed to unfavour- 

 able conditions. H. Cruger in a report dated 1863 (published in 

 Agricultnral Ixccorcl, Trinidad. YII. Oct. 1892, 78) considers cue of 

 the most important of these as " a want of rain at a certain period." 



.J. H. Hart {Agricultural Hccord. II, 1890, 156) reports on an 

 outbreak of blight at Chaguanas in 1889, and is the first to mentio)i the 

 Froghopper, which he considers as the prime cause of the injury. 



There seems to have been no serious outbreak of blight between this 

 time and 1906, which year was the first of a series of severe attacks. 

 In this year Hart {Bull. Misc. Informatio77, Botanic Dejjt. Trinidad 

 VII. 152) reprinted his earlier report and laid more stress on the 

 presence of root fungi in the blighted areas. He says "on some estates 

 the canes were badly infested with Root Fungus {Marasmius) and on 

 these the attack of Froghoppers appeared more pronounced than on 

 other fields where better health prevailed." 



In the same jear A. E. Collens made two reports on outbreaks of 

 blight at Harmony Hall and Brechin Castle, in which he notes the 

 presence of both root fungi and Froghoppers, and, without definitely 

 stating which he believes to be the more imjiortant cause, he gives 

 directions for control which deal with both agents. 



In 1909, after three severe outbreaks in successive years. Hart 

 {Proc. Agr. Soc, Tiinidad and Tobago IX. 32-40) has changed his 

 opinion as to the importance of the Froghopper and now considers that 

 root fungus is at least as important as the insect, the Froghopper being 

 however a contributory cause. He writes ''■Marasmius is usually to be 



