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Late Summer/Early Fall Prescribed Burning

Hot dry summers present an opportunity to conduct some growing season burns in August and September.  There are a myriad of reasons to utilize prescribed fire in late summer or early fall.  Like any management action, careful planning and clear objectives should drive decisions on when and where to apply fire.

Old fields and grasslands, where excessive undesirable young woody species are present, can benefit from late summer fire.  Species like cedar, honey locust, osage orange and many other nuisance sprouts can be topkilled, particularly those under 2 inches dbh.  This resets the clock by 3 years here in the Midwest.  Longer term control can be seen further west in dryer climates.  Since cedars don’t stump sprout, prescribed fire on young cedars will eliminate them permanently.  Since there will be minimal time for regrowth of vegetation prior to the first fall frost, consider the size of burn units.  You will want to leave plenty of unburned units available to ensure adequate cover through fall and winter.  We typically recommend burning no more than 1/4 of the open land acreage in the late summer/fall.  

Thick warm season grass stands with minimal diversity can also benefit from late summer/fall burning.  Rank grass stands provide little benefit to deer, quail or turkeys, since they lack the broadleaf plants to attract insects that ground nesting birds need throughout the summer, which are some of the same plants deer also desire in summer.  Late summer or fall fire will damage the root crowns of warm season grasses like Indian grass and Big Bluestem, two of the most common culprits in rank grass plantings.  Additionally, the exposure to freezing and thawing all winter will further damage the root crowns of the grasses, making them grow less vigorously next spring.  This gives the forbs (weeds, broadleaf plants, whatever you want to call them) a head start the following growing season.  These annual and perennial forbs will supply much needed food in the form leaves, seeds and insect attraction.

Prescribed fire can also be used late summer to prepare a site for a fall herbicide application.  If cool season grasses need to be eliminated as part of a field conversion, or just due to their encroachment into a warm season grass planting or old field, prescribed fire can help remove the excessive above ground vegetative growth.  The removal of all the above ground growth will help insure good chemical contact on the target plant after some regrowth period.  Additionally, the fire will help stimulate fall growth of the cool season grass.  Then, after the desirable vegetation has become dormant, typically after the first frost of fall, glyphosate can be applied to kill out the undesirable cool season grass.

Finally, late summer/early fall burning helps replicate a historical disturbance that occurred in many habitats, particularly grasslands.  Hot, dry summers resulted in occasional lightning strike induced fires that sometimes raced across miles of open landscapes.  Additionally, Native Americans utilized late summer fire to attract game, and fall fires to prepare sites for winter encampments.  Removing the fuel load insured the encampment would not be burned over during a winter wildfire event.  Our native habitats need these historical disturbances to maintain proper ecological function.

Whatever your reason for using summer/fall fire, make sure you have quality firelines installed and adequate hydration for your crew.  We often burn when temperatures exceed 95 degrees, and it can take a toll on your body.  But the results are definitely worth the sweat soaked shirt!

Kyle Hedges - Land & Legacy Consultant