Garden Column for the Salisbury Post

Darrell Blackwelder

December 14, 2005

     Interest in pecans seems to peak during the holiday season. Many in Rowan County have pecan trees and all seem to have a few problems. Below are questions about pecans I receive in December.      

      **Question: My pecans don't produce each year.  How can I make them bare fruit each year? 

     Answer: Pollination may be the problem. Male and female flowers of the pecan are separate and do very often do not mature at the same time during the spring. Late frosts, heavy rainfalls or other physical factors may prevent adequate pollination.  Planting more than one pecan variety increases chances of pollination.

      **My pecans have dark spot on the kernels? What is this and how do I prevent this?

     Answer:  Stink bugs and leaf‑footed stink bugs are the culprits of this type of damage. These insects feed on the kernels when the shell is hardening and black, chocolate colored stains appear on nuts later.  This is often referred to as biter pit.  Many stink bug species over‑winter in orchard debris (leaves and spend nut casings). Eggs are laid on grass and in soybean fields or vegetable gardens producing as many as generations a year. Remove debris from around the tree and don't plant soybeans nearby if possible. Reduce broadleaf weeds underneath the tree.

      **My pecans are fuzzy and shriveled.  What causes this?

Answer: This problem is a result of stress during growing season, often by inadequate moisture.  Irrigation during late summer droughts is the only solution to this problem.

     **After a few weeks my pecans become bitter.  What can I do to prevent this?

     Answer: Pecans have high oil content.  Over time the oils within the nut turn rancid.  Put nuts in the refrigerator for short term storage. Put them in the freezer for long term storage for a year or longer.

     **I have these black spots all over nut case and leaves.

What is this and how do I control the problem? 

Answer: The problem is caused by a fungus called pecan scab.

There is no effect control with pesticides because of shear size of some trees.  Plant resistant varieties and remove leaf and limb debris as soon as possible to prevent re-infection.

     **When and how should I fertilize my pecan trees?  Answer: Usually in early spring in late February or early March is the best time to fertilize the tree. The recommended fertilizer program is to apply 6 pounds of 10-10-10 fertilizer per inch of trunk diameter. Pecan trees are prone to have zinc deficiencies. The fertilizer listed above should contain 1 to 2 percent zinc. Special pecan fertilizers can be found at farm supplies and retail outlets.

Darrell Blackwelder is an agricultural agent in charge of horticulture with the North Carolina Cooperative Extension Service in Rowan County. For archived garden columns or other information, visit the Rowan County Master Gardener web site at www.rowanmastergardener.com , e-mail Darrell_Blackwelder@ncsu.edu