[Companion Crops]
Rye, vetch, Italian ryegrass, and fall-sown grain crops are often seeded with crimson clover. Besides making a valuable addition to the clover ([fig. 4]), these companion crops help bolster up a thin stand. Such crops are seeded from one-half to one-third the normal crop rate and the crimson clover is seeded at the normal rate. Planting is done at the same time, but, as a greater depth is required for most of the seed of the companion crops, two seeding operations are necessary. In Tennessee, farmers often use a mixture of 5 pounds of red clover and 10 pounds of crimson clover per acre with excellent results. The first growth of the mixture may be grazed or harvested for hay or for crimson clover seed, while the second crop is wholly red clover.
Figure 4.—Crimson clover and rye, an excellent green-manure combination.
[Diseases and Insects]
The only serious disease that affects crimson clover is stem rot. The effect of this disease is seen in the early spring and is characterized by the plants dying in patches. The stems rot at the surface of the soil or where they join the crown. The occurrence of continued damp cool weather during early spring favors the development of the disease. Exclusion of clover and other legumes from the rotation for a period of 2 to 5 years is the best control method.
Sandy soils in the southern part of the crimson clover belt are often infested with nematodes. Nematode injury results in a stunting and yellowing of the plants and is most prevalent in the southern part of the region. While the clover-seed chalcid, the pea aphid, and other insects sometimes become numerous in crimson clover, insects do not ordinarily cause appreciable damage.