26 THE SUGAR-CANE INSECTS OF HAWAII. 
Yellow Caledonia, will be a leading factor in preventing another 
epidemic. One other point was brought home to the Hawaiian 
planters as a result of the leafhopper epidemic, and that was the 
importance of intensive cultivation. The grass and weeds must be 
kept down by cultivation, the low places drained, and the impover- 
ished lands fertilized. Those plantations which were in a high state 
of cultivation suffered less from the leafhopper attack, and the estates 
provided with the means of irrigation, in addition, suffered the mini- 
mum loss. There is a direct relation between intensive cultivation, 
fertilization, and irrigation and the amount of insect injury to any 
erop, showing that these operations are of great value in lessening 
insect damage. 
Diversification of crops.—Sugar cane has been the leading crop in 
Hawaii since the days when the islands turned from the sandal-wood 
trade and the whaling fleet as a source of revenue. Some of the lands 
have been under cultivation to cane continuously for over twenty-five 
years. The time is at hand when the sugar-cane planters will find 
it both necessary and more profitable to diversify their crop. Some 
lands at present require a change from sugar cane, and the lands which 
are still highly productive will also require such a change as the years 
go by. When the general practice of inter-cropping cane with other 
plants does come, it will have a direct bearing on the control of the 
sugar-cane insects, the leafhopper included. The intermediate crop 
may be one of value in itself or one to be plowed under for green 
manure. Since it is not wise to cease the practice of burning off the 
trash after harvesting the cane, the planters can find no cheaper source 
of plant food, or no way in which the requisite texture and water- 
holding capacity of the soil can be more easily obtained than by 
removing their lands from cane cultivation in regular rotation and 
planting some nitrogen-gathering plant to be turned under when the 
land is put back into cane. 
Control of the rind disease of sugar cane.—As has been mentioned, 
leafhopper injury is aggravated by the presence of the rind disease. 
In a discussion of the rind disease (Melanconiwm sacchari) Dr. N. A. 
Cobb says: @ 
According to my observations on thousands of cuttings dug up on some twenty-five 
plantations a considerable part of the cuttings in some fields fail to grow on account 
of this disease, which, being present in the cuttings when they are planted, develops 
sufficiently to prevent germination. This is a difficult thing wholly to avoid by 
means of inspection of the seed, as the disease is sometimes present in cane that looks 
sound. It may be suspected to be present in any cane that has been attacked on the 
stalks by leaf-hopper or by borers. Other wounds that give admission to the rind 
disease fungus are those made by injudicious stripping, cracks at the bottom of the 
eane due to the effects of storms, and what are sometimes called ‘‘growth cracks.’’ 

4 Coss, N. A.—Fungus maladies of the sugar cane. <(Hawaiian Sugar Planters’ 
Exp. Sta., Div. Path., Bul. 5, p. 107, 1906. 
