Newsletter

Summer Pests July - Sept.

Tips for Keep-

ing Bees Safe

Fall Nutrient Status &

Needles Loss continued with insert

538 Scotts Creek Road, Suite 205

Sylva, N.C. 28779

828-586-4009

http://jackson.ces.ncsu.edu/

NC STATE UNIVERSITY

North Carolina Cooperative Extension Service

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July-September 2015

Jeffrey H. Owen, Area Christmas Tree Extension Specialist, NC State University Usually, you can’t shake needles off of a dormant Fraser fir Christmas tree whether it is standing in the field or recently cut. Time and again, people have overheated, frozen, or dried the tree in full sun and the needles still held tight. The tree’s ability to hold up in retail lots from Chicago to South Florida and beyond reflects the often harsh and unpredictable condi-tions of its native Southern Appalachian mountain range. The Problem: When a NC grown Fraser fir tree does lose needles, it’s unusual and a point of concern for the grower. In certain years, some Fraser fir Christmas trees shed more than the normal amount of needles in late September or early October. Losing older needles that have been on the tree for 5 to 7 years is normal. However, trees in some problem fields lose current year needles at this time. Trees in other fields may lose multiple years of needles all at once. The top, middle, or entire tree may be affected. Some trees that were tagged in summer can become unsalable. Needle loss problems seldom show up before trees are of a marketable age and size. Trees greatly increase the amount of foliage with each progressive year. This creates an increasing demand for water and nutrients. Factors which may have been adequate or marginal for a smaller tree become limiting as the tree grows. The failure of symptoms to be expressed in younger trees has often lulled growers into complacency only to be surprised by needle loss in trees already tagged for market. Growers easily identify needle loss as it occurs in the field, but the same factors that caused needle loss in trees in the field can contribute to needle loss after harvest when the trees are out of a grower’s hands. A problem that only showed up in a few standing trees could involve more cut trees. As trees are stressed during shipping and display, some problems that were marginal in the field can be aggravated to the point where needle loss occurs. Physiology of Needle Loss Needle loss occurs when a series of chemical reactions result in a weakening of plant tissue along an abscission or separation zone at the base of the leaf. As cells in the abscission zone break down, the needle can shake or fall off. The balance of three plant hormones as influ-enced by light, temperature, moisture content, and other environmental factors is thought to control the formation of the abscission zone. Dormancy is a separate physiological process that becomes critical in needle retention of har-vested Christmas trees later in the season. Dormancy of Fraser firs and other Christmas trees only occurs with the seasonal accumulation of cold temperatures uninterrupted by extended

warm spells. Continued page 4.

Summer Pests: July - Early September

The following information was taken from the NCSU Christmas Tree Portal Website: http://www.ces.ncsu.edu/fletcher/programs/xmas/control/window/summer.html Stages of pests. Most pests continue to be very active through the summer, though BTA and HRM are not.

• RBM — Mites are actively feeding and reproducing. Mites are residing in the newly

formed rosette bud and will remain there until bud break of next year.

• EHS — All stages present. Another flush of white as the males pupate and emerge is seen in August.

• BWA — Adults laying eggs. All stages including eggs, crawlers, nymphs and adults present.

• BTA — Eggs.

• Cinara aphids — Cinara aphids may be active.

• SSM — All stages present including eggs, immatures, and adults.

• HRM — Typically inactive as it is too hot except for the highest elevation fields.

• Predators — Most predators are active and commonly found. Advantages to applications during the summer. This is a good time to control EHS. Ci-nara aphid control for trees to be harvested can begin in August, so combing control of those two pests can occur then. Twig aphid control for the following year with bifenthrin products is better later in the summer as well. Disadvantages to applications during the summer. It is hot, making it hard for the ap-plicator to safely spray and wear the appropriate PPE. Predators and pollinators are both very active and can be impacted by pesticide applications.

*BTA control is for the following spring. **Cinara aphid control is for harvest of that year.

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Tips For Keeping Bees Safe

USE IPM PRACTICES

Only use an insecticide when you really need to. Unnecessary pesticides waste moneys, kill natural predators, and can actually make pest problems worse. To learn how best to manage pests, see the Christmas Tree Portal at http://christmastrees.ces.ncsu.edu When an insecticide treatment is required, use only the materials that are necessary. Don’t mix insecticides unless there are multiple pests that need controlling that require the combi-nation. Use the lowest toxicity product. Be sure to read the label and follow all label direc-tions. Warnings about bees are found in the Environmental Hazards section near the front of the label. Labels can be found at the NCSU Christmas tree Portal. Spray at night, early in the morning or in the evening whenever pos-sible to avoid problems with bees. Bees are not actively foraging when it is cold. Spraying in the late fall and winter is a good way to avoid impacts on pollinators and predators both. Know Your Neighbors Another important step in protecting bees is to know your neighbors. How close is your Christmas tree farm to bee hives? Many people keep backyard bees. These may be a hobby, or it may be a way for a family to earn much needed money from the sale of honey. Each bee hive represents several hundred dollars in investment and hours of care on the part of the bee keeper. Bees can travel as much as five miles from a hive, but typically stay within a couple of miles. Bee keepers can “keep the girls at home” if you need to spray a field with an insecticide. They can do this by stopping the entrance to the hive for several days, or even by moving the hive to another location. By communicating in advance with the bee keeper, they will have time to protect their bees. Scout for Bees

Honey bees are not always in Christmas tree fields even if there are flowering ground covers. In some instances, there are no nearby bee-hives. In other instances, the bees are working trees such as sour-wood, and the clover in fields is not as attractive to them. But, espe-cially in the early spring when flowering mustard or purple dead-nettle are blooming in tree fields, the Christmas tree field may be one of the few sources of food, and bees will be very attracted to the area. The only way to know if bees are in a field is to scout for them. Visit the field during mid-day and sunny weather be-fore spraying to see how many bees you observe.

Stop Ground Covers From Flowering

Tall flowers such as mustard can be chopped down to reduce flowering. Treat-ments with low rates of Roundup will also burn back flowers for several weeks. Do this prior to treatment, then scout to make sure bees are no longer actively visit-ing a site before spraying. Another option is to mow your groundcover.

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During a mild autumn, many woody plants fail to undergo the physiological changes that induce dormancy. Without full dormancy, foliage respires more quickly and trees are under greater moisture stress. Judging by the history of poor needle retention in trees harvested too early in the fall, the stress of rapid foliage respiration in non-dormant cut trees may induce the hormonal shifts that lead to needle loss the same as drought stress in the field.

Contributing Factors: The factors that contribute to changes in the hormonal balances related to premature needle loss vary from field to field and season to season. Climate, soil type, plant nutrition, and individual tree genetics all can influence a tree’s ability to hold needles. However, once trees are planted, the only factor that growers can readily alter is plant nutri-tion. Climate and soil are most important from the management standpoint in the ways that they effect root func-tion and nutrient status. It still comes down to what nutrients are high or low on the soil and tissue reports. Over the years, a number of different nutrient problems have been linked to needle loss in Fraser fir. Only careful soil and tissue sampling and some knowledge of field history can determine which fertility problem underlies needle loss. Consider the following nutrient problems in relation to your own fertility management situation:

Salt Injury: Excessive fertilization can induce trees to shed needles at any time of year when high salt concentrations develop in plant tissues. Symptoms of salt injury have developed soon after fertilizer application or even months later during a fall drought when plants underwent moisture stress and the subsequent salt concentration in tissue. High salts can develop after excessively high per acre applications or when a proper amount of fertilizer is improperly ap-plied over too small an area near each tree. Salt injury is most likely when fertilizers with higher salt indexes are used such as murate of potash (0-0-60), ammonium nitrate (33-0-0) or calcium nitrate (15-0-0).

Symptoms of salt injury in the field can include wilting of new growth, freckling of needles with narrow brown bands, needle loss of current season needles or of all needles in parts of the tree, branch tip dieback, to total death of the tree. Inner bark and the surface of the wood is often discolored to a gray-brown color or even a sticky black tar.

Jackson County Center 538 Scotts Creek Road, Suite 205 Sylva, NC 28779

NC STATE UNIVERSITY

Christy Bredenkamp, Extension Agent

Agriculture-Horticulture

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