More and Better Clover

by E. A. HOLLOWELL

HIGH COSTS of feed for livestock, lower yields of a later cash crop, and inadequate conservation of the soil are all closely associated with failures or poor stands of clover. Too frequently those conditions are blamed on unfavorable weather. Too infrequently do farmers look for the real causes of the failures.

When they do, it is often found that the seed used was of a variety not adapted to the local climatic conditions and lacking in resistance to the diseases and insect pests prevalent in the region. The purpose of this article is to report the progress that has been made in improving clover in recent years.

The problems involved are complex. First, there are more than 14 species of true clovers (Trifolium spp.) and sweetclovers (Melilotus spp.) that are important in United States agriculture. To determine proper objectives of an improvement program, thorough studies must be made of the method of reproduction of each species and of the plant diseases and insect pests that attack it. Special breeding techniques must be developed in many cases to obtain the characteristics that go to make a superior variety. After a new variety has been developed by breeding methods, it must be tested adequately to determine its range of adaptation and its cultural requirements. Finally, seed stocks of the improved and tested variety must be increased and maintained in a pure condition before it can be released for farm use.

Besides the usual factors of adaptation, resistance to low and fluctuating winter temperatures, potato leafhopper, and several leaf-spot diseases, northern anthracnose has recently been recognized as a serious disease in the northern and central regions of the main red clover belt. Breeders are searching for strains resistant to the disease. Another problem is one of adaptation to day-length during the growing season. Within certain limits, strains or varieties adapted to northern latitudes are lower yielding when planted farther south. On the other hand, varieties adapted to the lower latitudes give increased yields as they are moved northward until environmental factors, such as winter hardiness and diseases, limit their productivity. A step toward control of these problems has been made by the development of two new red-clover varieties—Midland and Cumberland.

Improved Red Clover

Midland red clover originated as a composite of equal proportions of four old strains, one each from Ohio, Indiana, Illinois, and Iowa. Thirteen years of testing it and increasing seed stocks were involved in developing Midland. Midland is winter hardy, has good growth characteristics, and has some resistance to northern anthracnose. As the name implies, it is adapted to the middle or central part of the Corn Belt States, and to areas with similar climatic conditions in the Eastern States. In the West, its use is recommended particularly for the production of certified seed for the eastern market. Depending on the environmental conditions, yields of one-quarter to three-quarters a ton more to the acre can be expected of Midland over common red clover.

Cumberland is a superior variety adapted to the southern part of the red clover belt. This southern red clover adaptation zone includes most of New Jersey, the southeastern corner of Pennsylvania, and the area generally south of 40° latitude. It originated as a composite of equal proportions of three identified strains, one each from Kentucky, Tennessee, and Virginia. It also is the result of 13 years of testing and increasing seed stocks and was developed cooperatively in State and Federal research and crop improvement programs. Cumberland has good growth characteristics. It is moderately resistant to southern anthracnose ( caused by the fungus Colletotrichum trifolii), and has some resistance to crown rot as well. When severe, southern anthracnose may kill the seedling or mature plants of common varieties of red clover, besides lowering the quality of the hay. Cumberland frequently yields a ton per acre more than unadapted red clover in the southern red clover belt.

But varieties even more resistant to diseases than Midland and Cumberland are in the making. A new kind highly resistant to the powdery mildew disease and more resistant to northern anthracnose than Midland is being increased and tested to determine its range of adaptation. Likewise, another new variety highly resistant to southern anthracnose is in the final testing stages. In preliminary tests at a few locations it has lived over into the third year, or second harvest year. If subsequent tests confirm the early results, this fact is of considerable significance. This evidence that by breeding to eliminate the hazards of the environment, there are possibilities of developing superior varieties of red clover that are perennial in length of life. If more extensive tests substantiate the earlier ones, these new varieties will be named and increased as rapidly as facilities permit.