A STUDY OF THE FACTORS OF CONTROL. 83 



On the other hand, there is this to be said against late planting. 

 AVhere the attack of the grubs is particularly severe, the growth stops 

 before any cane is made : hence the crop is a complete faikire. Whereas, 

 cane planted early usually has developed good-sized sticks before the 

 grubs destroy the roots, and in exceptional cases, when it is not lodged 

 by wind, it is possible to get a fair cut. Once it falls, however, deteriora- 

 tion quickly sets in, so the cane is condemned as unfit for milling; 

 furthermore, it is a terrible joli to get such a heavy crop off the ground 

 and prepare the soil for replanting. 



Since infested cane is ui)rooted so easily, it is of advantage to plant 

 deep. Though the grubs sometimes eat through stalks, letting them fall 

 over, the main trouble is tliat cane with roots too near the surface has no 

 support when these are eaten. In our Meringa experiments, 1918-9, we 

 had the drills made as deep as possible, with the result that the cane 

 all stood \\p, even though the work of the grulis was rather severe in some 

 of the plots. 



From time to time we have investigated the rooting systems of 

 various varieties of sugar-cane, particularly in regard to depth, and their 

 resistance to grub attack. Though Badila is a fairly soft cane, it usually 

 roots well ; ja^t it seems to suffer particularly from grubs. D 1135, on the 

 other hand, is generally recognised as an extremely hardy cane, and we 

 found that it was an especially deep rooter, most of the main roots going 

 straight down. At INIossman, where the grubs were once very destructive, 

 this cane is considered most resistant to them — in fact that district has 

 had little trouble from the pest since they have adopted this variety 

 extensively. 



For experiment, we tried 1) 1135 at Greenhills, but the soil was too 

 rich for it. Though the roots held well in the ground, even when grub- 

 injured, the canes were too long and limber, so that they bent over; then, 

 too, wherever they touched the soil, roots developed at the nodes, and 

 though the tops remained green it was a serious problem to harvest it. 

 This variety, however, does splendidly on poor forest land, where Badila 

 or other less hardy canes will not make a crop. 



It is generally conceded that plants poor in sugar germinate best. 

 It has also been observed that plants from short, grub-injured cane strike 

 Avell, probably for the same reason. For our Meringa plots, we got the 

 plants from a grubby field, the cane being so short that we scarcely got 

 more than one plant from a stick. However, the strike w^as perfect. 



During a visit to the Herbert River districts in ]\Iarch, 1921, I was 

 nuich interested in some most valuable experiments along this line, that 

 were being carried out by ]\Ir. E. D. Wilkinson, manager of the Macknade 

 ^lill. These referred, primarily, to the use of top-cuts only for plants, 

 and wider spacing in the drill. His results were most suggestive for 

 application to our problem. 



]\Ir. Wilkinson has kept careful record of the weight of cane from 

 each stool, for each successive crop, and even his third ratoons had a most 

 remarkable development — twenty-five large, thrifty sticks per stool. Yet 

 there has been no cultivation or chipping since the plant crop. He has 

 demonstrated that the top-cut is far superior to any of the others in 

 germination, giving a perfect strike, while, taking an average of all the 

 plants of a long stick, only about 80 per cent, germinate. He first cuts 

 off' the white cabbage-end, then takes a plant 12 inclies long; the balance 

 of the stick is discarded, and he has found that it pays to do this. 



