Crop Profile for Pecans in North Carolina

Prepared: December 1999

Revised: June 2005

 

General Production Information


Production Regions

North Carolina is on the northern fringe of the U.S. pecan production region.  The primary pecan production region in North Carolina is in the state’s Coastal Plain. However, there are a number of pecan operations that are being established in the lower Piedmont region of North Carolina.

 

Cultural Practices

Pecans are grown primarily in the eastern area of North Carolina in well-drained soils. Pecan acreage is increasing in North Carolina with growers looking to diversify their farming operations. However, pecans must be viewed as a long-term investment with 20 to 23 years required for breaking even. In order to make pecans viable many growers are planting to higher tree densities (30 to 35 trees per acre) initially and cropping trees early and then removing trees when necessary to approximately 8 to10 trees at orchard maturity (i.e., 18 to 20 years). Another option is for growers to "intercrop" the pecans with shallow rooted annual crops for the first 6 to 7 years. Because pecans are grown in lighter soils in the Coastal Plain, irrigation is strongly encouraged.

Most of the pecan orchards in North Carolina are relatively small compared to orchards in larger pecan producing states. Because of the size of North Carolina orchards, the use of fungicides and insecticides is drastically reduced. Most pecan growers use sanitation and cultural control practices to minimize insect and disease pressure and rely primarily on late-season insecticide applications to manage the pecan weevil, twig girdlers, and fall webworms. Because North Carolina orchards are smaller in size, the growers are able to be more intensive in their operations in areas such as training and pruning.

 

Worker Activities

(The following information was taken from the April 2005 Louisiana Pecan Crop Profile and adapted for North Carolina pecan production.) 

 

Insect and Mite Pests

Pecans in North Carolina are subject to attack by more than 20 insects and mites. However, only four insects, pecan weevils, twig girdlers, stink bugs and aphids are of economic importance in most years. It is critical that growers are able to recognize damage by these insects, understand their life history, employ insect monitoring tactics and subscribe to integrated pest management strategies. Some other insects of conce rn in some years include casebearers, leafminers, mites, fall webworms, spittlebugs, hickory shuckworm, phylloxeras and Asian ambrosia beetles.

The pecan weevil is the most serious late-season pest, as it attacks the nut. Its hosts include pecan and hickory. The life cycle of the pecan weevil consists of four stages and can span 3 years. Adult weevils emerge from the soil from August through September. Often a rain of 1 inch will trigger emergence. Adults crawl or fly, mate and live for many days. Females drill holes into nuts and lay eggs causing some nuts to fall in two or three days. Larvae pass through four stages feeding inside the nut. Nuts drop to the ground and the larva chews a circular hole through the shell and exits. They burrow into the soil where they remain for 1 or 2 years. They pupate and change into adults about 3 weeks later and remain in the soil until next August.

Both southern green stink bugs and leaf-footed bugs attack pecan nuts. They puncture nuts before shell hardening and after shell hardening. If feeding is early, the nuts drop. If the feeding is late then black spots or pits develop in the kernel. This damage is referred to as kernel spot or bitter pit. Both species overwinter as adults in debris. They emerge in the spring and lay eggs in grasses or soybeans. They move to pecans only as adults. There are four or five generations a year. Nymphs develop on grasses and vegetable crops.

The pecan twig girdler is a large beetle with long antennae that girdles twigs and small branches in September. Females lay clear glassy eggs in slits in the girdled branch. These branches fall to the ground when the wind blows. Larvae feed in the branch and exit to pupate in the soil. There is only one generation a year.

Two species of aphids attack pecans. Yellow and black aphids feed on leaves. Honeydew is deposited on the foliage and black sooty mold fungi develop. Damaged leaves may appear speckled or have patches that often turn brown and then die. Both species overwinter as eggs deposited in bark crevices. Nymphs are active in the spring. There may be 10 or more generations a year. Damaged leaves may appear speckled or have yellow patches that often turn brown and then die. Such feeding can cause leaves to drop prematurely.


Pest Management Strategies

Insect traps are used to catch pests and monitor their relative development and trigger additional sampling. Traps can also be used to time sprays. A black-light insect trap can be used for moths, beetles and stinkbugs. They should be suspended on a pulley and operated some 20 feet in the tree canopy. Pheromone traps containing a sex attractant are also available for many insects. They are species specific. There are two ways to monitor for pecan weevils using traps. First is by placing cone cage traps under tree drip line and recording the number of adult weevils collected in the traps. A second way is to use trunk band traps. Burlap bags can be wrapped around tree trunks of several trees in an orchard. Daily collections and destruction of male and female weevils indicate when to spray as well as provide some physical control.

Another method of monitoring pests in general is to place a sheet of plastic or cloth on the ground under trees. Trees can then be sprayed with a knock down insecticide application. One can then return and record the insect found on the sheet. One could also jar the tree and look for insects. In the case of twig girdlers, fallen twigs can be examined for the smooth cut surface done by adult beetles.


Insecticides and Miticides

First Prepollination (buds are burst and first leaves are showing)

Aphids:

Aphids, mites, leaf phylloxera:

First Cover (young nuts first appear)

Nut casebearers, leaf casebearers, mites, and stink bugs:

Fourth through Sixth Cover

Aphids, pecan weevils, hickory shuckworms, and stink bugs:

Pecan weevil sprays should be made every seven days from mid-August through mid-September.


Insecticide and Miticide Use Estimates

Growers generally use Sevin for control pecan weevils, twig girdlers and worms. They will use Thiodan for control of Asian Ambrosia beetles.


Current Insecticide and Miticide Recommendations for Pecans

Current North Carolina Cooperative Extension Service recommendations for insecticide and miticide use on pecans (including information on formulations, application rates, and precautions/limitations) are provided in the following table from the North Carolina Agricultural Chemicals Manual:

Table 7-13: Pecan Spray Program http://ipm.ncsu.edu/agchem/chptr7/711.pdf


Cultural Control Practices

 

Diseases

Scab is the most common and damaging pecan disease in North Carolina. It is caused by a fungus that affects rapidly-growing leaves, shoots, and nuts. Symptoms on all parts of the plant are similar. Leaf symptoms first appear on the underside as tiny olive-brown lesions on the veins. Later, leaf symptoms appear on the upper surface as small olive-brown to black spots. Several spots may develop on the husk to form black blotches or may blacken the entire surface of the husks causing the nuts to drop prematurely in the husk. However, as mentioned earlier, very few North Carolina pecan growers use fungicides to minimize disease pressure due to the smaller size of their orchards and the high cost of equipment necessary for mature pecan orchards.


Fungicides

Scab:


Fungicide Use Estimates

Estimates of fungicide use are not available for pecan production in North Carolina.


Current Fungicide Recommendations for Pecans

Current North Carolina Cooperative Extension Service recommendations for fungicide use on pecans (including information on formulations, application rates, and precautions/limitations) are provided in the following table from the North Carolina Agricultural Chemicals Manual:

Table 7-13: Pecan Spray Program http://ipm.ncsu.edu/agchem/chptr7/711.pdf


Cultural Control Practices

The most effective strategy to control pecan scab is to plant varieties, which have some degree of resistance such as Cape Fear, Elliott, Gloria Grande, and Stuart.

 

Weeds

One of the best management strategies for a pecan orchard floor is to use a grass alley with a vegetation-free strip. This vegetation-free strip can be established and maintained with herbicide. The permanent grass sod between the tree rows will minimize soil erosion, increase soil aeration and permeability, and support equipment movement through the orchard during wet weather. The vegetation-free strip will help to minimize soil moisture and nutrient competition of grasses in the alley with trees, resulting in optimum tree and nut growth. The vegetation-free strip may help minimize tree damage or loss from voles during the dormant season.

It is best to avoid mechanical cultivation, which can injure tree roots and increase the potential spread of crown gall in established orchards.


Herbicide Considerations

Several herbicides are registered for use in pecans. Some are preemergence herbicides that control weeds that have not emerged and others are postemergence herbicides that control emerged weeds. Preemergence herbicides control germinating weed seeds but do not usually give acceptable control of emerged weeds. However, some herbicides (i.e., Karmex) will control weeds both preemergence and postemergence. Postemergence herbicides are most effective in controlling actively growing weeds.

A good weed management program for pecans consists of the application of a preemergence herbicide(s) in late winter (late February to first week in March) for preemergence control of summer weeds. Applying a non-selective postemergence herbicide (Gramoxone MAX, Rely) to burn down existing vegetation is recommended when applying preemergence herbicides. Throughout the summer and especially prior to harvest, postemergence herbicides should be used to control escaped weeds. A post-harvest application of a preemergence herbicide(s) to control fall or winter weeds is also recommended. Continued use of the same herbicide or herbicides with the same mechanism of control over several years may lead to resistant weeds. Whenever possible, growers are encouraged to rotate herbicides with different mechanisms of action.


Pest Management Strategies

It is important to scout orchards monthly to determine the weed species present. Scouting allows early identification of difficult-to-control weeds, which may help prevent them from establishing in the entire orchard. If difficult weeds are noticed for the first time in an orchard, they need to be removed before they produce seed. This can be done by hand removing weeds or spot treating weeds with a non-selective postemergence herbicide like glyphosate, paraquat, or glufosinate (Roundup, Gramoxone, or Rely, respectively). If weeds are mature and have produced seed, remove the weed from the orchard when damp to prevent the spread of seed in the orchard. Scouting also gives growers an opportunity to know the weeds that have not been controlled by their weed management program so that adjustments in this program can be made in the future. Growers should consider the potential for weeds located around the borders of the orchard to infest it.


Herbicides

Preemergence Herbicides:

Postemergence Herbicides:


Herbicide Use Estimates

Estimates of herbicide use are not available for pecan production in North Carolina.


Current Herbicide Recommendations for Pecans

Current North Carolina Cooperative Extension Service recommendations for herbicide use on pecans (including information on formulations, application rates, and precautions/limitations) are provided in the following table from the North Carolina Agricultural Chemicals Manual:

Table 8-11B: Chemical Weed Control in Fruit Crops – Tree Fruits http://ipm.ncsu.edu/agchem/chptr8/814.pdf

 

Contacts

Michael L. Parker
Extension Specialist (Tree Fruit)
Department of Horticultural Science
North Carolina State University
Campus Box 7609
Raleigh, NC 27695-7609
Telephone: (919) 515-1198
E-mail: Mike_Parker@ncsu.edu

Wayne E. Mitchem
Extension Weed Management Specialist
Department of Horticultural Science
North Carolina State University
Mountain Horticultural Crops Research and Extension Center
455 Research Drive
Fletcher, NC 28732
Telephone: (828) 684-3562
E-mail: Wayne_Mitchem@ncsu.edu

Kenneth A. Sorensen
Extension Specialist
Department of Entomology
North Carolina State University
Campus Box 7626
Raleigh, NC 27695-7626
Telephone: (919) 515-1662
E-mail: Kenneth_Sorensen@ncsu.edu

Mr. Bill Bunn
President
North Carolina Pecan Growers Association
P.O. Box 435
Bailey, NC 27807
Telephone: (919) 266-1809

 

References

  1. Hall, M., R. Sanderlin, J. Pyzner, M. Grodner, and C. Graham.  2005.  Crop Profile for Louisiana Pecans.  April 2005.  Louisiana AgCenter, Louisiana State University, Baton Rouge, LA.  http://www.ipmcenters.org/cropprofiles/docs/lapecans.html
  2. Jones, R.K. and D.F. Ritchie.1991. Some common pecan diseases and their control in North Carolina. North Carolina State University. Ornamental Disease Information Note No. 3.
  3. Mitchem, W.E., and M.L. Parker.  2005. Orchard floor management in pecans. North Carolina State University, Horticulture Information Leaflet 380.
  4. Parker, M.L. and K.A. Sorensen. 1994. Growing pecans in North Carolina, North Carolina Cooperative Extension Service Bulletin, AG-81.
  5. Sherrell, E. M. (ed.).  2004.  North Carolina Agricultural Statistics 2004.  Publication No. 204.  North Carolina Department of Agriculture & Consumer Services, Raleigh.
  6. Sorensen, K.A. 1994. Pecan insects and their management. North Carolina State University. Fruit Insect Note #P-2.

 

On-Line References

Some Common Pecan Diseases and Their Control in North Carolina
http://www.ces.ncsu.edu/depts/pp/notes/Ornamental/odin003/odin003.htm

Insects and Related Pests of Pecans
http://www.ces.ncsu.edu/depts/pp/notes/Ornamental/odin003/odin003.htm

Pecan Insects and Their Management
http://www.ces.ncsu.edu/depts/ent/notes/Fruits/fruitp2.html

Orchard-Floor Management in Pecans
http://www.ces.ncsu.edu/depts/hort/hil/hil-380.html

North Carolina Pest News
http://ipm.ncsu.edu/current_ipm/pest_news.html

Growing Pecans in North Carolina
http://www.ces.ncsu.edu/depts/hort/hil/ag81.html


Prepared by:

Michael L. Parker, Wayne E. Mitchem, Kenneth A. Sorensen, Bill Bunn, and Stephen J. Toth, Jr. (ed.)


The image of pecans is from the U. S. Department of Agriculture, Agricultural Research Service’s Image Gallery at: http://www.ars.usda.gov/is/graphics/photos/).