Many Afghan pine trees in the Permian Basin recently and rather suddenly displayed a lot of dead needles. Since this pine generally performs well and grows large, the developing problem has become a tree care emergency of sorts for many homeowners. What is going on and what can be done about it?
A sudden change in growing conditions often predisposes a tree to disease-causing agents. Late spring brought above average rainfall to the Permian Basin. Furthermore, several neighborhoods were particularly hard-hit by hail.
What do we know? The problem is complex. Rather than being widespread across the Permian basin, sick Afghans appear to be mostly confined to home landscapes in areas that received extensive rainfall and hail damage. Samples from these areas were submitted to the Texas A&M plant pathology lab by certified arborist James Tuttle. The lab identified a fungus called Diplodia pinea. Diplodia tip blight is known for causing dieback up to eight inches or more including small limbs.
The problem also gave early indications of pine tip moth injury. While the samples were being analyzed at the lab, certified arborists Mark Walter and Leslie Oldham confirmed the presence of pine tip moth larvae in many weakened pines. Several samples had high numbers of these insects.
Trees under stress are susceptible to attack by both pests. Overwatering, underwatering, too much or improper fertilization, poor pruning techniques and physical injury are all factors that may cause stress in trees. It is highly probable that these opportunistic plant-destroying pests have been thriving in certain stressed trees made worse by the combination of increased warmth and humidity.
What can be done? Arborists recommend good sanitary practices. Rake up fallen twig and needle debris that could otherwise harbor pests. Avoid pruning, without a goal. Fertilize prescriptively based on what your soil contains and what your tree needs. When the soil is saturated from rainfall, turn off the irrigation to minimize tree stress.
If you suspect you have a tree weakened by diplodia blight or pine tip moth, contact the Texas A&M AgriLife Extension office at 686-4700. You should also contact your certified arborist. If you do not have an arborist, visit http://www.treesaregood.org to locate one.