The pine tree, which is a favorite for Christmas festivities in numerous homes, is susceptible to various pest and disease attacks. Early detection of attacks is vital as a control measure and will minimize damage caused. Most conifer trees infestations will hardly cause death unless very severe, but will impact on the growth rate, slowing it down. We take a look at some of the more prevalent pest and disease attacks and give tips in management and control.
The Spruce Spider Mite commonly attacks pine trees, as well as many others conifers. You will notice needles looking dirty and a silky substance forming on the branches. Mites appear under the leaves and are red, green and black in color. Trees begin dying from the bottom going upwards. Spray the pine trees every week with an insecticide containing hexakis.
Pine bark beetles attack the middle and upper body of the tree by tunnelling into the tree. The females lay eggs once inside the tree. After the larvae hatch they destroy the tree by tunnelling through the bark as well as eating it. After pupating, they emerge from the holes as adult bark beetles. Since the beetles spend much of their time destroying the tree from within, you may not quite notice the infestation until much later when considerable damage has been done. Infestation by bark beetles causes the pine needles to turn yellow, orange and reddish-brown in color. You may also identify tiny holes on the tree trunk or small clumps of tube-shaped pitch near the holes. If the tree is severely weakened, it is best to remove it. Otherwise, use a heavy rubber mallet to smash at the tubes followed by spraying the tree trunk with an insecticide containing lindane. Water the tree every 4 to 6 weeks and more frequently during drier weather. Also, avoid leaving pine trimmings near the tree as this attracts beetles.
Pine tree root nematodes attack the roots and cause stunted growth. The needles turn yellow-brown in color and branches weaken, eventually dying off. Chemical preparations do not have any effect on root nematodes so it is best to control them through soil fumigation before planting.
Pine Pitch Canker is a fungal disease that is characterized by cankers on the tree trunk which ooze a resin, yellowish in color. The needles turn brown and branches begin to die. It is spread by boring insects as well as wind. Although the disease cannot be treated, you can manage it by using insecticides to control the presence and damaging activities of the boring beetles.
Root rot causes thin foliage at the top of the tree while dead trees have red needles. Apply dry granular borax on freshly cut stumps, and make sure you plant new trees at least 20 feet away.
Brown spot needle blight causes spots around the needles which gradually develop into bands, resulting in needles dying. Spots usually appear between May and October, but can also manifest at any other time. Fungicides containing maneb or chlorothalonil are effective as a control measure.