By Lenny Wells
University of Georgia

Georgia is blessed with a great climate for growing pecans, and
pecan trees are a common sight in yards statewide. But while they
can offer shade, tasty treats or extra income, many come up short
because of diseases and insects that thrive here, too.

Two problems particularly plague backyard pecan trees: pecan
aphids and a disease called pecan scab.

Yellow pecan aphids rob nutrients and water from pecan leaves.
They also produce a syrup-like solution called honeydew, which
coats the leaves and drips down onto cars and houses, where an
unsightly fungus called sooty mold develops. Large populations
often cause trees to shed leaves in late summer, too.

Culprits get worse

The damage inflicted by black pecan aphids is much worse. These
insects remove nutrients and water from the tree’s leaves, too,
but in doing so they release a toxin into the plant.

This toxin causes the leaves to develop bright yellow spots,
eventually killing that area of the leaf and turning it brown.
When populations are heavy, black pecan aphids can defoliate a
tree.

As bad as aphids are, though, the main reason backyard trees fail
to produce pecans is pecan scab. This disease develops and
spreads during rainy time, particularly when the nut is growing.

Nuts infected with pecan scab develop black spots on the shuck.
Many will be covered so the entire nut turns black and falls
before it’s fully developed.

Ways to improve

Completely removing and destroying the leaves and shucks on which
the disease overwinters can help reduce the carry-over of scab
and other diseases. Removing low limbs can allow greater air
flow, too, which helps to reduce the leaf wetness necessary for
infection.

In most cases, none of these problems can be controlled by
spraying pesticides on large, backyard pecan trees.

Pecan varieties, however, do vary in their susceptibility to
these problems, so take care to choose trees wisely.

Elliott is probably the ideal
backyard pecan. It has the best scab resistance available and
produces excellent quality nuts. Its small, teardrop-shaped nut
fills easily. It often brings a premium price because of its
plump, perfect halves.

The main problems with Elliott are that it may bear nuts only
every other year and can suffer from black and yellow aphid
problems. It is, however, relatively drought-tolerant for a pecan
tree.

Sumner suffers less from scab than
many varieties. However, it’s highly susceptible to damage from
black pecan aphids. Sumner has large nuts with well-developed
kernels. It produces lots of pecans at a young age, and is a
relatively consistent producer.

Stuart offers some level of scab
control, too, although the nuts will scab under heavy disease
pressure during wet weather. Many of the old yard trees in
Georgia are Stuarts.

These trees usually don’t suffer as much from black pecan aphids
as some other varieties do. But they often harbor large
populations of yellow aphids. Stuarts have large nuts with
well-filled kernels that shell easily. And they produce fairly
regularly.

Choosing the right variety for your yard may not eliminate
problems with pecans. But it can certainly make problems less
frequent.

To learn more about growing pecans and about many other
agricultural topics, contact your county UGA
Cooperative Extension agent.

(Lenny Wells is the University of Georgia Cooperative
Extension state pecan horticulturist and a Dougherty County
extension agent with the UGA College of Agricultural and
Environmental Sciences.)