Caring for Planted Trees
Following tree planting, proper care of the seedlings is necessary to help ensure a successful project. Competition from weeds, diseases and insects, damage from animals and environmental factors all play a role in the success of a reforestation project.
A regular monitoring program can help ensure the success of a reforestation project. At a minimum, you should evaluate plantations during the first growing season, four to five months after planting (although earlier evaluations may make it easier to diagnose problems), and again during the third growing season to verify survival and establishment. During the evaluation process make note of insect, disease, animal and competing vegetation problems.
Survival counts are a quick way to determine if replanting is necessary in order to meet management goals. Estimating survival on random 1/100-acre plots throughout the plantation can help you assess seedling survival. First, attach an 11.8 foot length of cord to a stake to represent the radius of a 1/100-acre plot. Then place the stake in the center of each plot and use the cord to determine which trees fall within the plot. Count the number of live and dead trees within each plot. Since each tree counted represents 100 trees per acre, multiply the number of live trees by 100 to determine the average number of live trees per acre. The number of live trees per acre divided by the total number of both live and dead trees per acre equals the survival percentage. Average the values from all the plots tallied to determine the survival for the whole plantation. The number of plots required to obtain a reliable survival estimate depends on the size of the plantation and the variability of survival within the plantation. A rule of thumb is to do one survival plot per acre for the first 10 acres and one additional plot for each additional 5 acres of plantation.
An alternative method (faster but potentially less accurate) is to select a row and count the number of live and dead trees. Switch rows periodically to sample across the entire plantation.
Learn more by viewing the video Green Side Up: Follow Up & Summary.
Control of competing vegetation before and after trees are planted often determines the success of a planting. Good site preparation will get seedlings off to a fast start, but it may be necessary to control competing weeds for at least three growing seasons or until the trees are well established.
Herbicides are often the most effective method for follow-up weed control. The proper choice of herbicide, timing and method of application are critical to insure that planted trees are not damaged. Detailed forestry herbicide information is available online.
Mechanical weed control may be suitable for some post-planting situations. Shallow disking or rototilling between rows is effective if care is used to avoid damaging the trees and their root systems. Mowing can reduce weed maturation and seed production and minimize rodent habitat, but it may also stimulate grass root growth and intensify competition for soil nutrients and water. Mowing can prevent the physical smothering of trees (i.e., lodging) as grasses and broadleaf plants die and fall over in the winter. Hand or mechanical cutting of woody vegetation may effectively release young seedlings, but repeated treatments may be needed due to stump sprouting.
Most forest plantings will experience some type of animal damage (e.g., browsing, rubbing, rodent bark feeding), however the severity of that damage will vary across planting sites and between tree species. Many different techniques can be employed to discourage severe wildlife damage.
Hunting can be an effective way to reduce local deer and rabbit populations. Rodenticides can be used to control mice, pocket gophers and meadow voles; however, these baits are hazardous and can affect non-target organisms. Rodenticides may be restricted and require a license.
Wildlife damage can be minimized by manipulating the habitat in and around the plantation. Mowing and other grass control measures will reduce rodent damage by removing their habitat and increasing access by predators such as hawks. Constructing raptor perches (posts that allow raptors to sit above the plantation) throughout the plantation can also improve rodent predation. The removal of brush and hedgerows virtually eliminates rabbit damage since they do not venture far from shelter. Manipulating the planting design can protect high hazard areas and discourage animals from entering the plantation. For example, plant several rows of less palatable trees, such as spruce, next to existing woodlands or along obvious travel corridors.
There are a wide variety of products available to protect seedlings. Electric fences, tree shelters, bud cap protectors and bud nets create a physical barrier between seedlings and animals. These devices must remain intact to be effective, which often requires routine maintenance. Repellents rely on fear, conditioned avoidance or taste to discourage animal from browsing. Repellents can work for short periods, but their effectiveness is reduced with time.
Insect and disease control
All plantations will experience some degree of insect and disease damage. If local pockets of damage develop, or problems persist, carefully identify the pest organism and assess the degree of damage prior to developing control recommendations. Once trees are damaged and weakened, they become susceptible to further attacks by pests. Proper identification becomes complicated when more than one organism or injury is present. For more information on diagnosis of insect and disease concerns, visit the forest health pages.
Insects causing the most damage to young tree plantations fall into three categories.
- Main stem and root pests, such as weevils and white grubs, feed on the main stem or root system and can cause serious tree mortality.
- Shoot or branch pests, such as scales and spittlebugs, feed on or within the shoots, causing branch damage or death.
- Defoliators, such as caterpillars and sawflies, feed on the leaves or needles.
Diseases can also be grouped into three broad categories.
- Root rots cause slowed leader growth and yellowing of the crown. Mushrooms may be evident around the base of an infected tree. Direct contact between roots will cause the disease to spread, resulting in pockets of infection.
- Cankers, stem rusts and shoot blights appear as lesions and/or swellings on stems and branches. These lesions will eventually cause dieback by girdling the stem.
- Foliage diseases, such as anthracnose and needle casts, appear as spots or lesions on needles and leaves.
Weather and environmental damage
Drought: Adequate soil moisture is crucial when the trees are young and lack fully developed root systems. Trees damaged by drought appear wilted and have yellow or brown foliage. The symptoms should appear similar throughout the plantation. Recovery is possible if seedlings get water before extensive damage is done. Drought will weaken seedlings and predispose them to insect and disease attacks.
Frost/freeze injury: Frost damage generally occurs in depressions or low areas where cold air settles. The foliage and/or young shoots will curl and die. Freeze injury can cause hardwood stems to die back the following growing season. Trees from inappropriate southern seed sources and species on the edge of their natural range are particularly susceptible. Frost damage rarely kills trees, but it does slow growth and predispose the seedling to insects and diseases.
Desiccation: Dry winter winds may cause desiccation — or the drying out — of conifer seedlings and turn needles reddish brown. This damage is mostly an aesthetic concern.
Herbicides: Improper application or timing of a herbicide can damage or kill seedlings. Foliage and shoots will usually appear yellow and have distorted growth. Detailed forestry herbicide information is available online.
Pollutants: Damage from pollutants can resemble many different problems and is difficult to identify. Sulfur dioxide, ozone and road salt are common tree damaging pollutants. White pine is particularly susceptible and should not be planted in areas frequently exposed to air pollution or road salt.
Fire: The best way to prevent a fire is to reduce the amount fuel in and around your plantation. Establish and maintain disked firebreaks and mowed access roads in order to prevent the spread of a fire and provide easy access by fire control equipment.