The month of August provides the second window of opportunity for establishing perennial forage stands this year. The primary risk with late summer forage seedings is having sufficient moisture for seed germination and plant establishment, which is a significant risk this summer given the low soil moisture status across many areas.
The decision to plant or not will have to be made for each individual field, considering soil moisture and the rain forecast. Rainfall/soil moisture in the few weeks immediately after seeding is the primary factor affecting successful establishment.
No-till seeding in August is an excellent choice to conserve soil moisture for good germination. Make sure that the field surface is relatively level and smooth if you plan to no-till seed because you will have to live with any field roughness for several years of harvesting operations.
Sclerotinia crown and stem rot is a concern with no-till seedings of alfalfa in late summer and especially where clover has been present in the past. This pathogen causes white mold on alfalfa seedlings and infects plants during cooler rainy spells in late October and November. Early August plantings dramatically improve the alfalfa’s ability to resist the infection. Late August seedings are very susceptible to this disease, with mid-August plantings being intermediate.
In a no-till situation, minimize competition from existing weeds by applying a glyphosate burndown before planting. Using no-till when herbicide-resistant weeds are present, such as marestail, creates a very difficult situation with no effective control options, so tillage is probably a better choice in those situations.
Post-emergence herbicide options exist for alfalfa to control late summer and fall emerging winter annual broadleaf weeds. A mid- to late fall application of Butyrac (2,4-DB), bromoxynil, Pursuit or Raptor are the primary herbicide options for winter annual broadleaf weeds. Fall application is much more effective than a spring application for control of these weeds especially if wild radish/wild turnip are in the weed mix. Pursuit and Raptor can control winter annual grasses in the fall in pure legume stands but not in a mixed alfalfa/grass planting. Consult the 2020 Ohio, Indiana, Illinois Weed Control Guide and always read the specific product label for guidelines on timing and rates before applying any product.
For conventional tillage seeding prepare a firm seedbed to ensure good seed-to-soil contact. Be aware that too much tillage depletes soil moisture and increases the risk of soil crusting. Follow the “footprint guide” that soil should be firm enough for a footprint to sink no deeper than one-half inch. Tilled seedbeds do not need a pre-plant herbicide.
Finally, keep in mind the following factors to increase establishment success.
Do not harvest a new perennial forage stand this fall. The ONLY exception to this rule is perennial and Italian ryegrass plantings. Mow or harvest those grasses to a two and a half to three-inch stubble in late November to improve winter survival. Do not cut any other species in the fall, especially legumes.
Source: Ohio State University
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