Distribution: Sunscald can occur anywhere night time winter temperatures drop below freezing.
Host: Thin bark trees, wounded trees, and water deficient trees. Mostly occurs in newly planted trees such as Maple or Linden.
Damage: Injury usually occurs on the south to southwest side. During night, the sap in the cambium layer freezes. then during the day, the sun shines on the south or southwest side thawing the sap on that side. These rapid changes in temperature cause death of cambial cells, leading to a separation of bark and wood. Control Tips-Wrapping the trunk with a light colored tree wrap during winter is useful in preventing damage. If a tree has already been damaged, proper fertilization is recommended to promote healing of the wound.
- Frost Injury
Distribution:Frost injury can occur in any region that is subject to near-freezing temperatures.
Hosts: Evergreens, fruit trees, rhododendrons, roses, and seedlings are a few of many plants affected. Birches, hard maples, dogwoods, red elm and willows show more tolerance to freezing temperatures.
Damage: Plants must acclimate to changes in temperature. Cold acclimation is a process involving the plant's ability to reduce or eliminate ice nucleating centers within cells or develop barriers to ice crystal formation. Water is tied up chemically and is unable to freeze. Plant species differ in the amount of time required to acclimate and their degree of acclimation.
- Iron Deficiency
Distribution:Iron deficiency is found whenever the following conditions are present: high soil pH, low or high temperatures, high soil moisture, lack of iron in the soil, excessive applications of phosphorous, relatively high concentrations of copper, manganese, and zinc in the soil, removal of the topsoil due to erosion or land leveling exposing the subsoil, and genetic susceptibility towards iron deficiency.
Hosts:Most deciduous and evergreen trees, shrubs and vines have varying degrees of susceptibility.
Control Tips: Proper fertilization can prevent or correct Iron Deficiency but often takes several years to correct. Iron trunk injections give quick results but do not cure the problem.
- Herbicide Damage
Definition:A herbicide is generally a chemical used for the purpose of suppressing or killing unwanted plants. For the purpose of this discussion, herbicide damage is simply the adverse effects to desirable plants resulting from either intentional or accidental herbicide exposure. There are many types of herbicides, with many new products being introduced each year; some are highly selective, while others affect plants of a much broader range. Most of the herbicides commonly used with ornamentals operate within a narrow margin of amounts and/or conditions, that will, or will not, damage desirable plants. This is particularly true in nurseries, which have a variety of plant material along with the variations in soil, moisture, and plant conditions. Herbicides provide a valuable tool, but must be used with extra caution, in and near ornamental and nursery situations.
Symptoms:Hormonal herbicide injury is commonly expressed by cupped leaves, unusual parallel leaf venation, chlorosis, mastic growth, and wavy or curled leaf margins.
Control Tips:The most important step is to be sure that herbicides are properly applied. Applicators should be informed about the products used and the potential for damage. When possible, select chemicals and application methods that pose a minimal risk to desirable plants and the environment. Once exposure has occurred, little can be done to minimize the initial effects. Washing herbicide off foliage can be effective if it is done during or soon after application. Soil-active herbicides can be deactivated on a limited scale with activated charcoal or similar products. Damaged plants will generally benefit from efforts that enhance growth. However, stimulating late season regrowth of lost foliage is undesirable. Plants weakened by herbicides may be predisposed to other kinds of damaging agents.