In some areas of the United States, red clover is often seeded in winter so that frost-thaw cycles can help to establish it in the ground. Red clover is often used in conjunction with other crops, such as wheat and fescue. Seeding is often done as soon as snow melts but before the ground has thawed. Though it's an effective way to start red clover crops, it makes young plants vulnerable to sudden frosts and subsequent injury.
Red clover (Trifolium pratense) is a short-lived perennial grown as a pasture legume and for hay. Though both early-flowering and late-flowering varieties are used, the early-flowering type, called medium red clover, is generally recommended, because it produces more hay. Red clover can be seeded in grass sod and provides excellent grazing forage. Though reed clover is often seeded as soon as the snow melts, it can suffer frost damage from unusually cold weather.
Frost Seeding of Red Clover
Alternating freezing and thawing can dislodge red clover plants from the soil, causing severe injury and death to large areas of the crop. Wet, poorly-drained land is most commonly affected by this problem.
Low-temperature injury can occur in red clover varieties that are not well adapted to the region in unusually cold winters. Late applications of nitrogen fertilizers tend to increase the likelihood of low-temperature injury, according to the University of Illinois Extension Service website.
Sleet storms of freezing rain often cause ice to form over large areas of fields, particularly on flat ground. This action can cause winter kill of entire fields. The sheets may also form in low areas when rain and snow settle.
Winter-seeded red clover begins to grow vigorously in early spring, but may incur frost injury in areas where cold air settles over plants. This can kill off the tops of the plants, but they recover quickly when warm temperatures return.
Sclerotinia Stem Rot
Sclerotinia stem rot can occur in red clover crops that were covered with snow late into the spring. The disease causes white mold and eventual dark, necrotic spots on leaves and stems and decline of the plants. Heavy loss of crops can occur with this disease, according to the Alberta Government Agricultural and Rural Development Department.
Fusarium spp. are soil-borne fungi that are often associated with red clover crops that have suffered winter injury. Roots may be completely rotted before crowns show damage, though symptoms can vary. Proper fertilizing and harvesting practices are helpful in preventing this disease.
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