Producing seed of forage species is not common in Ohio, because our climate is not as conducive to high yields of high quality seed of forages as in western and northwestern states. But each year around mid-July to early August I usually get a few questions about how best to produce red clover seed here in Ohio. Although seed produced by reputable seed dealers out west is of higher quality than what we can produce here in Ohio, there are a few management steps that will help improve the yield and quality of seed produced here in our region. Some of those steps begin with the first cutting of the year, which will soon be upon us. I will highlight a few key steps in this article, but for more details please refer to a factsheet from the University of Kentucky entitled “Producing red clover seed in Kentucky”, available online at http://www2.ca.uky.edu/agcomm/pubs/agr/agr2/agr2.pdf.
Cutting management – It is best to harvest seed from a red clover stand in the first full production year after a spring seeding (in second or third year of the stand). In the year you want to produce seed, the first crop should be harvested for hay because it will have too much vegetative growth for good seed yield and spring conditions are usually too wet for producing good quality seed. Timing of the first hay cutting is very important – first cutting should be made no later than 10 to 15 days after the first sign of blooms appear in the field. Delayed cutting will weaken the stand and reduce the seed yield produced later in the summer. The seed harvest should be made on either the second or third harvest when summer conditions are usually more conducive to seed production in Ohio.
Weed management – Many broadleaf weed seeds are difficult to clean from red clover seed, so areas harvested for seed should be as free of weeds as possible. About the only broadleaf herbicide option available for red clover is 2,4-DB and it does not control well-established broadleaf weeds and has a limited range even for seedling broadleaf weeds. So it is important to establish and maintain a vigorous red clover stand from the beginning if seed is to be harvested from the field. It the area to be harvested for seed is relatively small, the most feasible way to keep weed seeds out of the clover seed is to rogue them out by hand prior to seed harvest.
Pollination – Seed production in red clover is highly dependent on insect pollination, which occurs primarily through bumblebees in Ohio. It is important to use insecticides cautiously to prevent reducing the population of pollinators. It might pay to set a couple hives of bumblebees near the field during flowering.
Harvesting seed – You can thresh the heads in your palm to check the condition of the seed, but it will be ready for harvest when the majority of the seed heads are brown or black. Seed can be harvested by combining directly or after windrowing. Results from University of Kentucky trials indicate that there is no great advantage to using chemical desiccants provided the seed heads are dry and the combine screens and airblasts are set as recommended by the manufacturer. Chemical desiccation (e.g. with paraquat) might be advisable if the field is excessively weedy.
Seed storage and processing – It is critical that seed be dry enough to prevent heating. Heating will dramatically reduce the germination of the seed. Seed cleaning is also very important because seed harvested by combine will not be clean enough for planting. Refer to the factsheet referenced below for more details on these two important management steps.
Taylor, N.L., D.M. TeKrony, and J. Henning. 1996. Producing red clover seed in Kentucky. Univ. of Kentucky Coop. Ext. Serv. Factsheet AGR-2. Available online at http://www2.ca.uky.edu/agcomm/pubs/agr/agr2/agr2.pdf.