8i AUSTEALIAX SUGAE-CANE BEETLES AND THEIE ALLIES. 



In planting his drills are 5 feet apart, and he experimented both 

 with spacing of 3 feet 6 inches and 5 feet in the drills, in comparison with 

 a continuous line of abutting plants, Avhich is the current field practice. 

 Most surprisingly, the plots planted 5 feet square have given the heaviest 

 yield per acre right through all the crops. Mr. Wilkinson explained that 

 this can be done by using top plants only, and thus getting a perfect 

 strike at the start, for he has also demonstrated that replanting the misses 

 does not pay. These retarded stools never come to much in the plant 

 rrop, and though it is the popular belief that they catch up in the ratoon 

 this is not the case ; his individual records show that a small stool at the 

 beginning remains a small stool always ; he pointed some of these out to 

 me in the third ratoon crop. 



As to manipulation, the plant ero]i was well cultivated and kept free 

 of weeds; when cut the trash was left where it fell, evenly distributed 

 over the ground, with no relieving over the rows. Any stiff weeds that 

 pushed through Avere cut off with a sickle, using care not to disturb the 

 blanket of trash. When the cane had gotten well started, about February, 

 ammonium sulphate was applied by throwing it under the stools as much 

 as possible, to avoid feeding the grass in the centres. This gave the cane 

 such a boost that there was no further trouble with weeds. The successive 

 ratoon crops were handled in the same way, and the results were most 

 instructive. The trash had all rotted down into a thick covering of black 

 loamy humus, and even the nutgrass had been smothered out in the 

 centres by the dense shade of the luxuriantly growing cane. 



I was at once impressed with the possibilities of these manipulations 

 in our work, for grubby soils are sadly lacking in humus. This phase of 

 the problem is discussed in later sections. 



(3) There are numerous factors that increase the vigour of the 

 plant, and all of these should be considered as valuable aids in combating 

 grtibs; for cane in a thrifty growing condition will resist injury to a 

 considerable degree. Among these factors I Avould suggest the advantage 

 of a thorough preparation of the soil, application of lime, supplying 

 humus, cultivation, fertilisers, and irrigation. 



Thorough preparation of the soil before planting undoubtedl.y pays 

 under any condition, for it makes the crop get away with a jnmp. 

 Furthermore, repeated ploughing, as has been shoAvn above, does much 

 to free the land from grubs. Lime, too, being practically wanting in most 

 of our tropical soils, improves the physical condition ancl assists materially 

 in developing a supply of humus, since a satisfactory green crop can 

 hardly be grown Avithout it. Furthermore, it improves the health of 

 soil bacteria and fungi, which are all-important in nitrification, hunuis- 

 forming, &c. 



With present methods of farming it is not surprising that humus 

 is usually lacking wherever the land has been Avorked for a few years. 

 It is a Avell-known fact that the grubs must have organic matter ; if they 

 cannot find sufficient in the soil, they attack the living roots. Moreover, 

 experiments have shown that they prefer humus and decaying organic 

 material, and that they will leave the roots alone as long as they can get 

 this natural food. 



On 19th April, 1918, two sets of experiments Avere started at the 

 insectary, u.sing megass mixed Avith soil in large pots ; untreated soil Avas 

 used for checks. In the first experiment, a large handful of megass 

 was mixed in soil about 5 inches beloAV a cane-set in each pot ; one pot Avas 



