Every year I have these holes in my Pecans
Published 9:00 pm Thursday, July 27, 2023
Pecan trees (Carya illinoinenis) are the hallmark of many landscapes in Eastern North Carolina. They become grand trees, spreading in a graceful prominence and producing some very tasty treats. By the way, one of my favorite treats is to shake about a pound of them in a bag with a teaspoon of mayonnaise to coat the outside of the nuts (sounds gross but I swear by it). Then, add some cinnamon sugar to the mix and give them another good shake. Lastly, throw them in the oven for about ten minutes at 350° and you have one of the easiest treats to make.
Many of these trees remain on estates that are passed from generation to generation. I have calls come in almost every year from folks who have inherited a home with a few pecans or even a small pecan orchard.
Pecans take about 10 to 12 years to begin producing and reach maturity around 20 years after planting. They need proper training when they are young to ensure good branch structure and tree growth. Fertilize according to a soil test from NCDA&CS. Before planting pecans, it is very important to get your soil tested and amended to the recommended pH of around 6.0 to 6.5 down to a depth of 16 inches in the soil profile. Plan to space the trees 60 to 70 feet from one another to ensure good nut production. Pecan trees are monecious which means that they have separate male and female flowers on the same tree. The flowers are ready at different times alternating from cultivar to cultivar. This is a mechanism to ensure cross pollination with other trees. For this reason, there must be at least two trees, a type one and a type two, to ensure good pollination.
Now that we are growing good trees, let’s talk about those pecan weevils. These little critters can cause some major loss in your pecan harvest if not taken care of in a timely manner. Pecan weevils spend most of the year in the ground. In the first or second week of August, they emerge as adults, crawl up the tree and lay eggs in the developing (soft) pecan. The larva emerges and begins to feed on the nut. Once the nut falls to the ground, the larva will chew a circular hole in the side of the nut and burrow into the soil to pupate. This process, of course, results in bad pecans.
There are some cultural controls that will help. The best cultural control is sanitation, get those bad nuts up and destroy them as quickly as possible. Unfortunately, there are no biological controls for pecan weevils.
Chemical controls with products containing the active ingredient Carbaryl remain the most effective. This can be found in name brands such as Sevin and Generics like Carbaryl 4F. There are numerous active ingredients marketed under the Sevin label so make certain to look at the active ingredient for Carbaryl. Always read and follow the label for application. And, make certain to wear the proper personal protection equipment (PPE). Begin to apply one of these products to the soil the first week of August. Apply around the tree from the dripline into the trunk and up the trunk around four feet high. Continue to apply this product every 10-14 days through mid-September. The catch here is that the pupae can live in the soil for up to five years. If weevils have been a problem in the past, it will take five to six years to get rid of them. The active ingredient bifenthrin can be used on the trunk as well. Spray this product from the base of the trunk to eight feet up the trunk. This product has a residual effectiveness of about seven days. Sticky traps can be used as well, one such product is Tree Tanglefoot Insect barrier. This product is wrapped around the tree five to six feet from the base of the trunk. The one problem all of these share is that they can’t protect against the flying insects, they will only protect against those adults that emerge and crawl up the tree. It is not practical for homeowners to apply insecticides to the canopy of large trees so this isn’t a recommendation from NC State University.
Another major pest of pecans is pecan scab. This is a fungal disease that causes the shucks to turn black and results in rotten pecans. There are a multitude of fungicides available to prevent scab but they require an air blast sprayer to reach up in the canopy of the tree. This is a very expensive sprayer mostly used in orchards. It is not cost effective for a homeowner to spray the trees.
Stink bugs and aphids can be seen on pecans in our area. They typically cause minor damage to production and are not a cause for concern in homeowner production. If you would like more information on growing pecans, there is a publication from NC State University titled Growing Pecans in North Carolina. This publication outlines everything from varieties to site conditions to training the trees and disease and pest issues. I highly recommend you get you copy of it if you are growing pecans. It is available at an Extension Center near you or it can be found online at https://content.ces.ncsu.edu/show_ep3_pdf/1597322329/1588/.
If you are itching to learn more about plant culture or have an issue in your home garden or landscape, send your questions to Gene Fox, Consumer Horticulture Agent with the North Carolina Cooperative Extension Service, please call at (252)946-0111. Extension Master Gardeners are available to answer your questions through our Greenline on Mondays and Wednesdays from 10-12 or through our new Facebook page, Beaufort County Master Gardeners. Stay tuned to Facebook and out website for details about our upcoming fall veggie sale and class.
Until then, Happy Gardening!