Southern Research Station Headquarters - Asheville, NC

White oak acorns. Photo credit: Southern Research Station

Late Spring Freeze Impact on Arkansas Acorn Production

Although freezing is only one of many factors that can impact acorn development, the late 2007 spring freeze will likely influence production of acorns in Arkansas. In areas where oak was in flower during the freeze there will probably be a significant reduction in the number of successful flowers. Basically any flower that froze will die.

However, where there is a mix of both red and white oak, the impact on the acorn crop will be somewhat ameliorated due to the difference in both flowering time and maturation between red and white oaks. Red oaks generally flower approximately two weeks prior to white oaks, so a single late freeze will generally impact one species more than the other. Flowering time will also vary from stand to stand, so that a single freeze will not impact all stands equally.

Additionally, it takes red oak acorns two years to mature while white oaks mature in only one year. Thus, although multiple late spring freezing events could kill flowers of both red and white oaks, acorns in the red oak group that are already maturing from the previous year pollination will likely survive.

With all of this variation across the landscape the impact of the late 2007 spring freeze on acorn production will also vary across the landscape acting as a natural buffer to larger landscape scale losses. At this point in time it's too early to predict what the fall 2007 or 2008 acorn crop will be. The best way for a manager to understand what type of mast (acorns available to wildlife as food) crop exists in a stand in a given year would be to conduct a mast survey in late summer or early fall (after acorn maturation but before acorn drop).

Other conditions that can impact acorn development:

Environmental

• Extended periods of damp weather during flowering/pollen shedding could reduce the effectiveness of pollen shedding
• Drought during the growing season may stimulate oaks to conserve energy by aborting acorns
• High temperatures
• Insects
• Humidity

Tree physiology

• Tree age - maximum acorn production generally occurs on trees between 50 and 80 years old. However, smaller acorn crops can be realized on trees as young as 20 years.
• A large acorn crop on a tree one year may reduce a trees resources, thus the following year's acorn production may be reduced while tree resources are replenished.

Martin Spetich  501-623-1180 Ext. 105 mspetich@fs.fed.us

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