Pine trees in Union County and all of NC are under constant pressure by several species of pine beetles, most of which are native species. Pines can resist attack from these beetles when the pines are young and vigorous, but when they get older and/or receive more shade and less full sun, they lose vigor and succumb to the beetles and the diseases vectored by these beetles. This is a normal process as pines are what we call a pioneer species in the forest, coming in as part of the first group of trees after disturbance such as a fire, and they are naturally replaced by the second group of longer-lived trees such as oaks and other hardwoods. So we commonly have stands of hardwoods with pines mixed in. Pines grow more quickly and grow up first, but later get overtaken by hardwoods. Homeowners call me as these pines are getting shaded out and dying from beetle infestation, but what they are witnessing is a natural process of forest succession.
In Union County, many homes are built in or near former pine plantations where pines were planted in tight spacing that were intended to be thinned around age 15, again around age 25, and then harvested around age 40-45 had that land stayed as pine plantation. If the land transitions from pine plantation to new homes, that thinning gets skipped and we are left with pines planted very close together which exacerbates the problem as they shade each other out more quickly. In a situation where homeowners buy homes that come with pines with this kind of spacing, I generally recommend picking the best 20% of pines and removing the other 80% - this is an appropriate spacing if we want these pines to remain as a viable part of the landscaping of a new home. This 20/80 prescription is very generalized and may not apply to all situations.
Pines have developed a reputation for being susceptible to windthrow. While they do develop a shallow root system while growing quite tall, most of this reputation is owed to developing homes in and near stands of tall pines. Clearing some pines and creating a new forest edge results in a sudden change in local wind patterns. This means that trees which grew up protected from the wind on all sides are suddenly exposed to strong bursts. Pines planted in plantations at tight spacing are especially dependent on each other during wind events – suddenly creating a new edge and exposing these tall, skinny pines to new wind dynamics is the primary reason for windthrow.
Note that pines planted in full sun as part of landscaping live much longer, healthier lives with less insect or disease problems. Loblolly pine is the most common in Union County and can live to be over 100 years old. Pines provide evergreen screening and are part of my screening recommendations with proper spacing. The pine tree is the state tree of NC as it is very important to our economy and adds great beauty to our landscapes.
What can you do to extend the life of your pine trees? As this article discusses, there is no effective pesticide treatment. The best treatment is to keep your pine trees healthy by keeping the root system healthy. These prescriptions apply to all landscape trees, not just pine trees. This means possibly adding some supplemental water during times of drought. Keeping the root system mulched and adding some organic compost. Our heavy clay soils in Union County easily compact under pressure which results in poor soil health, so keep the lawnmower out from under trees because lawnmower tires compact our clay soils. Do not attempt to grow grass under trees – that area should be mulched and reserved for the tree’s root system. But feel free to plant flowers and shrubs under trees. In addition to tree root health, pines can be promoted by thinning them to ensure they receive full sun.
