It's no secret we're all a bit nutty in Louisiana. After all, we have to be to enjoy living in a soup-bowl climate nine to ten months out of the year. It's also no secret that we're particularly partial to pecans. This native nut of Louisiana and the American South finds its way into many classic Louisiana culinary creations. After all, there would be no pecan pralines without New Orleans.
Designated the official state nut of Louisiana in 2023, the pecan (Carya illinoinensis) has a rich history intertwined with that of our state. Native Americans relied on pecans as a portable, nutrient-rich food source and helped spread the tree throughout the South. When European settlers arrived in Louisiana, they encountered native groves of pecan trees and harvested the nuts for food. Commercial cultivation of pecan trees developed much later, after the Civil War, as growers recognized the crop's economic potential.
Early commercial production relied heavily on native tree plantings and naturally occurring groves. That changed following the Philadelphia Centennial Exposition in 1876, the first World's Fair hosted in the United States. During the exposition, the first named cultivated pecan variety, 'Centennial,' was introduced. The cultivar originated from a superior native tree growing across the Mississippi River from Oak Alley Plantation in Vacherie, Louisiana. Scion wood from this tree was grafted onto rootstocks at Oak Alley by a Creole slave named Antoine, who successfully propagated 126 trees from the original selection.
The development of improved varieties with higher yields and better nut quality helped establish commercial pecan orchards throughout the South. Pecans gained additional popularity during the World Wars as Americans sought alternative sources of protein and healthy fats. Today, the United States leads the world in pecan production and consumption, with Georgia, New Mexico, and Texas ranking among the top producing states.
While Louisiana has a long and proud history with pecans, growing them successfully can present challenges. You may already be noticing a couple of these on your own trees. Two issues can be especially troublesome this time of year: pecan scab disease and late-summer nut drop of immature fruit.
Pecan scab is a fungal disease caused by Venturia effusa (formerly Fusicladium effusum). The fungus infects actively growing, immature plant tissue throughout the spring and summer. Frequent rainfall, prolonged leaf wetness, and high humidity favor disease development. Symptoms appear as black, velvety, round-to-elongated lesions on leaves, twigs, and nut shucks. Severe infections can result in premature defoliation, reduced tree vigor, poor nut quality, and significant yield loss.
Given Louisiana's humid climate and abundant rainfall, pecan scab is one of the most important diseases affecting pecan trees. Commercial growers routinely apply fungicides to protect orchards from infection. While fungicides can be effective, homeowners often have limited access to labeled products and typically lack the equipment necessary to adequately spray large, mature trees. Small pump sprayers, backpack sprayers, and most 12-volt sprayers generally cannot provide sufficient canopy coverage for effective disease control.
Fortunately, decades of breeding efforts have produced pecan varieties with moderate to excellent resistance to pecan scab. For homeowners, selecting resistant varieties remains the most effective long-term management strategy. Improving air circulation and sunlight penetration through selective pruning can also help reduce disease pressure in established trees.
Pecan trees generally require cross-pollination for consistent nut production. Cultivars are divided into two flowering types. Type I (protandrous) cultivars shed pollen before female flowers become receptive, while Type II (protogynous) cultivars have receptive female flowers before pollen is shed. Planting both flowering types helps ensure adequate pollination and good nut set.
Reliable Type I cultivars with good scab resistance include Amling, Gafford, Jackson, and Syrup Mill. Recommended Type II cultivars include Elliott, Excel, Kanza, and McMillan. Keep in mind that some cultivars may become less resistant over time as new strains of the scab pathogen develop. Melrose is one example of a variety that has experienced reduced resistance in recent years.
Newly planted pecan trees typically require eight to twelve years before beginning significant nut production, depending on the cultivar and growing conditions. Mature trees may reach 70 to 100 feet in height with canopies spreading 40 to 75 feet wide. Proper spacing is essential for airflow, sunlight penetration, and long-term tree health. Trees should generally be planted 50 to 70 feet apart.
Fall is an excellent time to plant pecan trees in Louisiana and establish a productive addition to the home landscape or orchard.
Next week, we'll discuss late-summer nut drop and the steps homeowners can take to improve pecan production and yield in the home orchard.
