BlTTiiER AND HAPIZ. 159 



On March 7tli, 1908, a short trench of Purph' iMauritius was 

 planted, half with setts dipped in a pnre suspension of the leaf form 

 of CoIletotricJnwt, the other half not inoculated. On April 30th, (52 

 healthy shoots belonging to 50 setts were found in the latter and 

 30 belonging to 26 setts in the former, (lermination had been 

 approximately e({ual in tlie two halves. 



On March r2th, 1910, half a trench was similarly planted with 

 setts of Ashy Mauritius, dipped in a pure suspension of the leaf 

 form of CoUetotrichnm. Germination was better in the inoculated 

 than in the control half, and on May 3rd there were 182 shoots in 

 the former and 130 in the latter. On June 21st there were 77 healthy 

 and 80 withering shoots in the inoculated half-trench, while the 

 control half-trench had 156 healthy and 55 withering. As already 

 stated the controls this year developed red rot, probably from 

 infection during irrigation. A full trench of the same cane near by 

 but supplied by a separate distributary had, as above mentioned, 

 on this date 784 healthy shoots. 



In all these cases the presence of Colletotrichum. was demon- 

 strated in several of the withering shoots, and they establish fully 

 that true red rot can arise from infection from both the stem and the 

 leaf forms of the fungus through the planted setts. Not only is the 

 disease perpetuated by planting previously diseased setts, but 

 healthy setts can be infected at the time of planting, if reached by 

 the fungus, and, no doubt, subsecpient infection from below ground 

 can also occur. It is well known from previous work that the fungus 

 can enter at wounds exposing the pith, such as the cut ends of the 

 setts, and, as will be shown below, infection through the roots also 

 readily occurs. The course of the infection up into the stem can be 

 traced in many cases and direct connection between the mycelium 

 in the sett and that in the new shoot established. Raciborski' 

 has very correctly described the passage of the disease from the 

 planted sett up into the young shoot. 



' Raciborski, y\. Dc ncstrijdiii;: van lid lood-snot. Anlucf v.d., Java-iSuikevindustrie, 

 V, 1897. p. 1133. 



