"Warts" on Pecan Leaves Can Be Galls

Wart-like Pecan leaf galls.          PHOTO/Renae Lemon

Over the past couple of weeks, several county residents have emailed photos and/or brought in examples of infested pecan leaves, concerned that their trees may be diseased.

UGA's publication "Pecan Trees for the Home or Backyard Orchard", by UGA specialists Lenny Wells, Will Hudson, and Jason Brock, explains that disease can interfere with good production of nuts, so it is easy to see why our residents would be concerned. A reduced harvest of delicious pecans would be a great loss!

The good news is that, so far, all of the affected leaves have been infested by galls, rather than disease. In the popped-open gall just above the 5 and 3/4 mark on the ruler in the photo above, one of the culprits is just barely visible, looking somewhat like a little white worm.

The University of Kentucky's publication "Pecan Insects"  offers this information about the leaf gall that is typically caused by an insect called Phylloxera:

"This aphid-like pest produces galls on new pecan growth. Leaves, twigs and nuts may be affected. Phylloxera over winter as eggs in bark crevices. In the spring eggs hatch and the tiny nymphs feed on tender young growth, secreting a substance which stimulates plant tissues to develop into galls. When the nymph matures, eggs are deposited in the gall. Young nymphs develop within the gall. The gall splits in several weeks liberating them. Several generations are produced each year, as long as there is fresh young growth on the tree.

Control is initiated with the use of a dormant oil application. During the growing season, controls should target the "crawler" stage before the galls form. Once the gall is formed the damage is done. The crawler is active just before or at bud-break. Controls initiated after the start of gall formation are not effective."

In other words, it's too late to treat now. Many of the infested leaves will fall, and it could be that nut production will be reduced, but the galls do not always appear on the same tree every year. It may help to clean up fallen leaves as part a control program.

A UGA in Thomas County Ag blog post has this to add about Pecan Phylloxera: "Many beneficial insects like lady bugs, lacewings, and syrphid fly larvae feed on phylloxera and eggs after each generation of galls open."

Upcoming Events

Celebrate Horticulture Week with a Day at Green Meadows Preserve

Tuesday, July 8, 9:00 a.m. – 1:00 p.m. Bring a picnic and enjoy all the park has to offer as Cobb Extension celebrates both Horticulture Week and the 100^th anniversary of the founding of Cooperative Extension. Bluebird Trail Walk begins at 9:30 a.m. Stay to learn about the Cherokee Garden, historic Period Garden, new organic orchard, bee hives, and community garden! 3780 Dallas Hwy, Powder Springs, 30127 (Intersection of Dallas Hwy and Old Hamilton Road). Free and open to the public. For information, call 770-528-4070.

Rain Barrel Workshop

Thursday, July 10, 10:00 a.m. to 1:00 p.m. Reduce your outdoor watering bill! Learn about and build a rain barrel to take home for personal use. Horticulture Agent Neil Tarver, of UGA Extension/Cobb County, will lead the class in Cobb Extension's second floor classroom at 678 South Cobb Drive, Marietta, GA, 30060. $15 supply fee; preregistration required. Call 770-528-4070 or email Cornelius.tarver@cobbcounty.org.

Smart Irrigation

Saturday, July 12, 9:00 a.m. – 1:00 p.m. Class conducted by the Cobb Water System and UGA Extension/Cobb County will help homeowners save both water and money. Learn technologies and practices to improve efficiency of water use. Class will be held in the second floor classroom at 678 South Cobb Drive, Marietta, GA, 30060. Free program, but please preregister at 770-419-6244 or email waterefficiency@cobbcounty.org.

Planning the Fall Vegetable Garden

Thursday, July 24, 6:30 – 8:00 p.m. Amy Whitney, of UGA Extension/Cobb County, will explain what to grow, when to plant, and how to find space for the fall garden.  Class will be held in the second floor classroom at 678 South Cobb Drive, Marietta, GA, 30060. Free program, but please preregister by calling 770-528-4070.

ALSO, come meet Cobb Extension staff and some of our Master Gardener Volunteers at the Marietta Square Farmer’s Market. We will be there on July 5, July 26, and August 30 to answer questions on canning, food preservation, and gardening. Bring sick plants (or large pieces of them) for help with diagnosis and treatment options, and bring bugs for identification.

100 Years of Cooperative Extension

The Cooperative Extension system in the United States was founded in 1914, and University of Georgia is celebrating the 100-year milestone. Below is a video about the role of Extension in Georgia through the years:

Watering the Vegetable Garden

One of the best pieces of garden-watering advice any of us are likely to come across was written by UGA Extension Horticulturalist Robert Westerfield in the publication "Conserving water in the vegetable garden".  He wrote, "Do not stand in the garden and spray plants lightly every day. This is the worst possible way to water."

What is the alternative? He tells us:  "Instead, soak the soil to a depth of at least 6 to 8 inches to encourage roots to seek water and nutrients deep in the soil. With an extensive, deep root system, plants are better able to withstand dry periods."

His publication includes the information that, for gardens in sandy soils, keeping the soil moist at that depth may require watering every 4-5 days; in clay soils, watering may be required only every 7 to 10 days. To help conserve water in the garden, the publication also recommends the use of mulch, to slow evaporation from the soil.

Westerfield's publication "Mulching vegetables" adds that a good mulch layer will not just conserve water. In addition,, it "suppresses weed growth, reduces fertilizer leaching and cools the soil. Mulch also serves as a barrier between the plant and the soil, helping prevent fruit rots that sometimes occur when vegetables touch the ground." This publication includes a list of mulches and their characteristics. The list can help home gardeners choose an appropriate mulch for their own gardens.

For gardeners who might want to use compost as mulch in the garden, the publication "Composting and mulching" by UGA Extension Horticulturalists Wayne McLauren (retired) and Gary Wade explains home composting in detail.

Making a completely finished compost can take months, but McLauren and Wade note that "Complete decomposition of the compost is not necessary when it is used as mulch." That is good news for gardeners who would like to mulch with compost from their landscape waste this summer!

(For fuller detail about watering, mulching, and composting, read the linked publiations.)

Pesticide Applicator Training

UGA Extension in Cobb County is scheduled to host a daylong class for Category 24 Ornamental and Turf Commercial Pesticide Applicator training. 

This class is for those seeking a license to prepare for the Category 24 Ornamental and Turf Commercial Pesticide Applicator's License exam.

When: Thursday, June 19, 2014, 8:00 a.m. to 4:00 p.m.
Where: Cobb Extension training room at 678 South Cobb Dr., Marietta, GA, 30060
Instructor: Neil Tarver, Cobb County Extension Agent
Cost: $10 per person
Registration: Please preregister; seating is limited. Call 770-528-4070 or email cornelius.tarver@cobbcounty.org to register or for more information.
 
The manuals "Applying Pesticides Correctly" and "Ornamental and Turfgrass Pest Management" will be reviewed.

The manuals needed for exam preparation can be purchased at the Cobb Extension Office. "Applying Pesticides Correctly" costs $15, and "Ornamental and Turfgrass Pest Management" costs $25.

Schedule
8:00 - 8:30 a.m., Registration
8:30 a.m. to noon, Class
Noon to 1:00 p.m., Lunch on your own
1:00 -4:00 p.m., Class