Pecan Trees Need TLC Too
Provided by Mack Johnson
Extension Horticultural Agent
Pe-can, pe-kahn, it doesn’t matter how you say it; it is still an iconic southern staple. Whether you admire the graceful sway of the leaves and branches in the spring, the cool shade offered in the summer, or the scrumptious flavor of the pecan nut in the fall and winter, it is a tree for every season. Many people have pecan trees on their property and don’t really appreciate them until autumn when the nuts begin to drop. By then it is too late to provide beneficial culture for the trees but hopefully it is a reminder that a pecan tree does need proper care to produce.
Pecan trees are monoecious, which means male and female flower structures are present on the same tree. However, because the timing of the pollen release often does not coincide with the maturity of the female “flower,” poor pollination rates can result in reduced nut production. Planting more than one variety and also more than one type can increase pollination rates. Pecan trees are separated into two pollination groups referred to as Type 1 and Type 2. Pollen is released at different times for each type requiring both types to be planted in an orchard for optimum production. Research has shown that ideal production happens when you have at least three varieties of pecan trees with at least one Type 1 and one Type 2 tree. This situation is best because the female flowers of the Type 1 are open at the same time the male flowers of the Type 2 are open. Without a tree present from each pollen category, prime nut production cannot be expected.
Many of the traditional pecan varieties are considered to be alternate or cyclic producers. This means the tree will produce well one year and to a lesser degree the next year. One of the popular varieties, Stuart, planted around older homesteads is considered an alternate producer.
In North Carolina, the major disease of concern is pecan scab. A fungus that attacks both the leaves and the shuck, the “flesh” covering the nut, causes this disease. Scab commonly occurs early in the season and is identified by small circular spots that range from olive to black in color on the leaves. Lesions on the nut shucks appear as sunken black spots and, in severe cases, may turn the entire shuck black. Cleaning up fallen debris, selecting resistant varieties, and applying fungicides early in the season aid pecan scab management. Scab overwinters in fallen limbs and leaves and can re-infect the tree the following year by rain and/or wind carrying fungal spores up in the new growth.
Pecan weevils decimate huge quantities of pecan nuts in Robeson County. To aid in controlling this pest, you should understand its lifecycle. The weevil overwinters in the ground, emerging in summer months as adults. The adults then mate and the females will impregnate a young developing pecan with an egg. Once hatched, the larvae will feed on the nut and cause early drop. On the ground, the larvae will chew an escape hole in the nutshell and burrow in the ground to overwinter for next year’s crop. Integrated pest management includes picking up and destroying fallen nuts as soon as possible. Spraying the ground from the trunk to the drip line beginning mid-August until mid-September with an appropriate insecticide will reduce the population.
Pecan tree nutrition can be managed using soil analysis and leaf analysis if needed. Soil samples should be collected and submitted for analysis at the same time each year, preferably in the fall. Each sample should be a composite of at least 20 subsamples from across the area with the same soil type. Fields under different management systems or different soil types should be sampled separately.
For questions on pecan tree culture or soil sampling, please contact Mack Johnson, Extension Horticultural Agent with North Carolina Cooperative Extension, Robeson County Center, at 910-671-3276 or by E-mail at Mack_Johnson@ncsu.edu. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, veteran status, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation.