The summer is drawing to an end and it is time to plant cover crops! Many cover crops need to be planted early to derive substantial benefit from them. Radishes have to be planted in August to develop a deep root system that can increase porosity and draw nitrates from deep in the soil profile to bring them up to the topsoil to be used by next year’s corn, oats, sorghum or sudangrass crop.
Oats should be planted now as well to put on substantial growth that can even be grazed or harvested this fall prior to winter-kill. Crimson clover and hairy vetch need to be planted in August or early September to develop enough growth to come through the winter and fix atmospheric nitrogen for next year.
Annual ryegrass should be planted preferably before mid-September to come to the winter successfully.
Winter-hardy small grain cover crops rye, triticale, and wheat are planted later but it is important to have the seed on the farm to enable planting right after harvest. For wheat, it is important to respect the hessian fly-free date, which varies from early September to early October in Pennsylvania, and/or consider getting resistant varieties.
Beyond Hessian fly, for small grains, including wheat, it is good to be mindful of aphids and the risk of planting too early. The earlier that small grain cover crops are planted, the greater likelihood that they could colonized by aphids, which have the potential of vectoring viruses, like barley yellow dwarf virus, to the cover crop, which could be then move to small grains being raise for grain.