We normally recommend that new spring seedings of forages be completed by early May in Ohio. Most of us have not even been able to consider planting yet, so how late do we dare try to plant forages this spring?
The quick answer I am suggesting for this year is May 15. I have planted that late before in central Ohio, although it is not ideal and involves higher risk of failure. If you can't get planted by May 15, consider waiting until August to seed the perennial forage stand.
Soil temperatures on April 29th ranged from 45 to 57 F, so they are still quite cool, and certainly wet. Most plants are lagging behind normal developmental stages for this time of year. That's why I think we can plant a little later this year; however, we know how quickly the weather can change to turn warm and dry.
The later we plant, the greater is the risk of hot, dry, windy weather that can kill new seedlings before they have a chance to establish strong root systems. Weed pressure will be greater with later planting, because seedlings will not get an early jump on annual weeds. It is essential to be prepared to control weeds in late plantings, and do so on a very timely basis! A burndown spray using glyphosate or paraquat before planting may be needed if weeds are already present, especially for no-till or reduced tillage seedings.
There are many good options for weed control in pure alfalfa seedings (see 2011 Weed Control Guide). Eptam and Balan can be pre-plant incorporated, but that requires extra time and effort during the busy planting time. So you may want to rely on post-emergence treatments. Most post products cannot be applied until the alfalfa has at least two to four trifoliolate leaves. During that wait, the weeds emerging with the alfalfa often outgrow it. So be ready to apply herbicides as soon as possible. This will be a good year for the Roundup Ready alfalfa option, because glyphosate is more effective on larger weeds and is very safe to young alfalfa seedlings.
There are fewer herbicide options for legumes other than alfalfa. Eptam and Balan can be applied pre-plant and Butyrac 200 can be post-applied on clovers and birdsfoot trefoil. There are no herbicide options for selective weed control in grass-legume seedings. Mowing is the only recourse for weed control.
Pure grass seedings used for forage can be treated for broadleaf weed control with dicamba after the grass reaches the 3-leaf stage, or with Rage D-Tech from the 5-leaf to boot stage. Be sure to read the label for appropriate rates and be aware of conditions favoring grass injury. Other options exist for broadleaf weed control once the grasses are "well established". There are no selective grass weed herbicides for grass seedings. Grassy weeds can become very competitive with late spring plantings. If annual grass weeds overtake the perennial grass seeding, the only option is to mow or graze the stand on a regular basis and keep the weeds from going to seed. Assuming the perennial forages establish, next year they will get the jump on weeds and you should have a clean stand.
When you use herbicides, always read the label carefully for proper application rates and restrictions. Be especially mindful of harvest timing restrictions after applying the herbicides.
Since planting season is being severely constrained this spring, consider how to get the job done more efficiently. One way to plant more quickly is to no-till or use reduced tillage, or seed into a stale seedbed if it was prepared last fall. Crop residues of corn, soybeans, and small grains are not a problem for most drills, but consider whether there are ridges along the rows that can make the field too rough for comfortable hay making.
Fluid seeding is another practice that can speed up planting. The seed is distributed in a carrier of water or in a fertilizer solution and sprayed onto a tilled seedbed. Custom application is recommended, because special equipment for good seed suspension and distribution is required. Prepare a firm seedbed before "spraying" seed and cultipack after it is applied. Seed should be mixed into solution at the field and applied immediately. Seeding legumes through dry fertilizer air spreaders can be successful as well on well-prepared, tilled seedbeds. The field should be cultipacked before and after broadcasting seed.
If you can't plant by mid-May, it's probably better to delay planting to August rather than seed just before hot weather sets in. To fill the interim gap, consider planting summer annual grasses such as sudangrass, pearl millet, sorghum-sudan, teff, and foxtail millet. All those species are normally planted in late May to early June when soils are warm. Foxtail millet won't regrow after an early August hay crop, so it might be the best option if you plan to seed the perennial stand in August. The other species options will require glyphosate to kill the stand before seeding in August.
Be ready, so you don't miss chances to plant. But above all, be careful and follow safe operating procedures. Haste not only makes waste, it can be very dangerous to your health.
Source: Mark Sulc, Ohio State University Extension Forage Specialist