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How Late Can I Plant Forages?

By Mark Sulc
 
The Ohio Agronomy Guide states that most cool-season perennial forages should be planted by the first of May. While some of you reading this article were able to plant forages by now, many of us (myself included) once again were not able to meet that deadline due to wet weather. So how hard and fast is the May 1 deadline, especially in a cold spring like we have experienced? Don’t we have a little more time to plant forages? I hate to say this, but the answer is neither simple nor clear cut.
 
The planting deadlines in the Ohio Agronomy Guide are based on data and years of experience of what is best management practice. The risk of stand establishment problems increases as we move further and further past the published deadlines. Tell me it will not turn hot and dry in early to mid-June and that weeds won’t emerge and grow like gangbusters with all the moisture we’ve had, then I’ll tell you that forage plantings can still be successful. Unfortunately, the law of averages increases against forage establishment success the later into May that we plant.
 
Having said all that, I will still try to plant my experiments up until May 11-15 in central Ohio. For each of us, it is a matter of balancing the risk versus the cost and competing tasks at hand. The rainfall outlook for May is normal to above normal with summer going from wet to drier. Temperatures in May will average near normal, but summer temperatures are projected to be above normal. The warmer summer and projected trend towards drier conditions is concerning for young forage seedlings trying to become established in June and July. Late established seedlings will be at risk of being exposed to moisture and heat stress before they have a strong root system established.
 
A firm seedbed and good seed placement are essential when seeding late, as this will help moisture move through the soil to the germinating seeds resulting in fast emergence and better early growth. Summer annual weeds will now be emerging with the forage seedlings and we know that weeds are very competitive and destructive when they emerge at the same time as new forage seedlings. In pure alfalfa stands, we have herbicide options that can help against both broadleaf and grassy weeds, in forage grass stands we have only broadleaf herbicide options, and in grass-legume mixtures we have virtually no effective herbicide options during establishment. You might want to seed a pure stand now to provide more herbicide options, and then interseed the secondary species into the stand in August.
 
Consider your options and management carefully before planting perennial cool-season forages the next two weeks. I’ve had success and failures in the past with late plantings – but the law of averages is starting to work against us now. The latest I have planted alfalfa was in a small experiment on June 2 in central Ohio. In that case I planted Roundup Ready alfalfa, and we received adequate rainfall through June. The stand established well, and we were able to control weeds effectively with Roundup. But the stand really did not produce much yield that seeding year. I think we had one small cutting the entire growing season. It was as if the alfalfa was just growing the root system so the above ground growth remained short all summer. The following year it produced excellent yields though.
 
An alternative to consider now is to plant a short-season annual forage crop that can be harvested in late June and July, followed by planting the cool-season perennial forage stand in early to mid-August when the law of averages will once again be more in favor of forage seedling establishment. This is what many of us had to do last year.
 
If you do plant in the next two weeks and the resulting stand ends up with thin spots, it will be important to work hard at keeping the thin areas from going to weed seed production this summer. You can interseed those areas with a no-till drill beginning in early August. This is true even for alfalfa seedings made this spring. Autotoxicity to alfalfa seedlings is not a big concern until the existing alfalfa plants are a year old. It is also possible to interseed alfalfa now into a thin stand of alfalfa that was planted last summer, and this spring is your last opportunity to do it; however, the discussion above about late plantings still applies to such interseedings.
 
Source : osu.edu