Since 1941 six varieties have been released for commercial planting in the United States. Two of these—C. P. 33/310 and C. P. 33/425—are specialty canes adapted to small areas in Louisiana, and it is improbable that either of them will ever occupy larger areas.

C. P. 33/243 is a good type, but it is susceptible to red rot and moderately susceptible to mosaic. In 1945 it occupied only 1 percent of the Louisiana acreage.

Two varieties—C. P. 36/105 and C. P. 34/79—were released in 1945. C. P. 36/105 has a wide range of adaptability in Louisiana. Because of its erect growth and resistance to lodging, it can be harvested by machines.

C. P. 34/79 was bred in 1934 and released to growers of southern Florida in 1945. It compares well with present varieties in the Everglades in yield of sugar per ton and tonnage of cane per acre. It also appears to be well adapted to the sand and the muck soils near Fells-mere, Fla. It is an early to midseason variety, with stalks of medium size that remain erect, except under the most adverse conditions. It is one of the few varieties grown in Florida that can be harvested by machine. It is not recommended for other areas.

The outstanding variety released during the war years was C. P. 34/120. It is grown successfully throughout the Cane Belt of Louisiana. It grows vigorously, with tall, erect stalks; the trash is easily removed, and it is adapted to machine harvesting. Because of its resistance to inversion after cutting, it is rapidly replacing Co. 281, a poor yielder that was continued in culture because it was the only good windrowing variety available. Farmers liked C. P. 34/120 and expanded it rapidly immediately following its release.

C. P. 36/13 was released to sugarcane farmers of Louisiana in July 1946. It compares favorably in yield and quality of cane with the leading commercial varieties. The stalks are of medium thickness and usually erect enough for machine harvest. It stubbles satisfactorily and has good windrowing qualities. In fiber content and juice extraction it equals C. P. 29/116. The outstanding characteristic of C. P. 36/13 is its high resistance to inversion of sucrose after cutting. In this respect it is probably superior to any variety thus far released.

C. P. 36/13 has an interesting origin. It was selected from a progeny of the cross P. O. J. 2725 X Honey sorghum. Its morphological characteristics and chromosome number show that it is not a hybrid of sugarcane and sorghum. P. O. J. 2725 does not have fertile pollen and it has never produced any selfed seedlings at Canal Point, but in most crosses with sorghum some seedlings that are not hybrids are produced. It is very probable, therefore, that the sorghum pollen induces development of seed (eggs of P. O. J. 2725) without fertilization, a process known as apomixis or apogamy.

C. P. 36/13 is similar to P. O. J. 2725 in color of stalks and resistance to inversion of sucrose. It differs in that stalks are somewhat smaller, earlier maturing, and with a higher sucrose content.

A large acreage of low-yielding, mosaic-susceptible P. O. J. varieties is still being grown for sirup. In the sirup section of Florida, Georgia, Alabama, Mississippi, Louisiana, and Texas, these should be replaced by the higher yielding varieties C. P. 29/116 and Co. 290. Co. 290 is susceptible to mosaic, but it can readily be kept free of disease by rogueing. C. P. 29/116 resists mosaic; in most places, it stubbles better than Co. 290, and produces a slightly greater yield of cane and sirup to the acre.

The superiority of the new varieties is shown by the definitely upward trend of yields since 1926 when the P. O. J. varieties were introduced to commercial culture in the United States. The first C. P. variety was released in 1930. From then on the acreage planted to C. P. varieties was expanded each year and by 1945 they occupied about 71 percent of the acreage planted to sugarcane in Louisiana. The annual yield of sugar per acre also increased 394 pounds more from 1936 to 1944 than from 1899 to 1908, when the old noble varieties gave their highest yields. In the period 1919 to 1926, following the incidence of mosaic, the yield from the noble varieties was only about 57 percent of present yields.

The increase was not due alone to the greater yield of cane by the new varieties; the quality of the new canes also was improved. The new kinds yield 26 pounds of sugar more per ton of cane than the old noble types.

Another advantage is that less seed cane is required for planting. When the noble varieties produced their highest yields (1899-1908) , 11.1 percent of the total acreage grown was used for seed, but with the introduction and spread of red rot and mosaic diseases, the figure rose to 23.1. In contrast, during the period from 1931 to 1944, only 9.8 percent of the total acreage of new varieties was required for seed.

THE AUTHOR

George B. Sartoris has been in charge of the sugarcane-breeding project of the Bureau of Plant Industry, Soils, and Agricultural Engineering for 20 years and is an authority on the wild and cultivated sugarcane varieties of the world. Most of the commercial sugarcane varieties now grown in the United States were developed by Dr. Sartoris.