Pecan trees are considered a staple in the landscape here in the south and particularly here in Georgia. In fact, Georgia is the nation’s largest pecan producing state and account for approximately one-third of all pecans produced in the United States. Here in northeast Georgia we have very little commercial production of pecans however during the early fall I tend to get various questions regarding mature pecan trees.
Although backyard or home orchard pecan trees seldom develop serious insect problems, treating the trees if pests do begin to build can be difficult. Whole-tree spraying as in commercial production is not an option for homeowners. However, some of the most likely pests can be controlled with simple insecticide applications. Pecan weevils can be controlled with a trunk application of an insecticide containing the active ingredient carbaryl. Treatment should usually begin in mid-August and repeated about three weeks later. Pecan aphids can also be controlled with root-zone applications of a systemic insecticide containing the active ingredient imidacloprid. Mix the labeled amount in a bucket of water and pour the solution around the base of the tree. For large trees, the insecticide should be mixed in two-to-three gallons of water per tree.
Diseases can severely limit pecan production. The major pecan disease is pecan scab which can devastate susceptible cultivars. Pecan scab occurs on leaves, twigs and nut shucks. Scab lesions are typically small, brown-to-black spots, one to five millimeters across. Sanitation can almost always help reduce losses from scab and other minor diseases. Nearly all fruit and foliage diseases of pecans, including scab, overwinter on plant parts infected the year before. Complete removal and destruction of leaves and shucks during the winter can reduce carry-over of scab and other diseases and help control them. So be sure to clean up those old leaves and pecan shucks this winter.
Soil fertility is one of the most important factors for bearing trees. If the trees are to produce a good crop, terminal growth should be six inches each year. In the absence soil test, broadcast four pounds of a complete fertilizer such as 10-10-10 for each inch of trunk diameter up to a maximum of 25 lbs. per tree. Trunk diameter should be measured at 4½ feet above soil level. Zinc nutrition is especially important in pecan production. Apply one pound of zinc sulfate to young trees and three to five pounds to large trees each year. Fertilizer should be applied in mid- to late March so it is too late to fertilizer for this year’s crop. However you can go ahead and put it on your to-do calendar. However something you can and should consider doing this fall is accessing your soil pH, this can be done through a soil test here at the extension office. In general, you want a pH of around 6-6.5 for bearing pecan trees. The soil test results will help determine the amount of lime you should apply to raise the pH to the needed level.
Water has more of an effect on pecan production than any other environmental factor, particularly where nut quality is concerned. Drought stress affects nut size and filling, as well as leaf and shoot growth. Adequate soil moisture is important at bud break for stimulating strong, vigorous growth and optimizing nut quantity and quality. If trees do not receive adequate soil moisture levels late in the season nut filling is affected. The nut filling stage occurs from about August 15 to the first week of October. The most critical period for water use is right now: during the first two weeks of September. Lack of sufficient water during the nut filling stage will lead to poorly-filled nuts, poor nut quality and increased alternate bearing.
Pecans are a staple for in so many of our favorite southern dishes. However it is important to remember that we must care for them properly for them to continue to produce quality nuts year after year.