US National Arboretum


Pest Management

Pest Management Tips: January

image of a ladybug     While live Christmas trees remain popular, they must be treated as very temporary visitors in your house during the holidays. They are not houseplants and will not survive long in conditions—low light and low humidity—found in our homes in winter. They should be kept as cool as possible, away from warm heater vents. Give them plenty of water and plan on moving them outside after a week or ten days. When planting them in your yard, remember that most of these small Christmas trees grow into very large trees 30 to 100 feet tall. For example, the cute little pine trees, with the soft, bluish foliage and usually pre-decorated with ornaments, are actually Italian stone pines. These stone pines, with adult, dark green needles over six inches, are hardy only to USDA zone 9. Where adapted, these Christmas trees grow up to 80 high and 40 wide, much too large for the average suburban lot.

image of a ladybug     Still procrastinating about raking those leaves? Do not let fallen leaves remain on your lawn all winter. Even a few weeks of dense leaf cover can kill or severely damage grasses. This heavy layer of leaves will keep the grass wet and dark, which will cause disease problems. Also, remove leaves from dwarf conifers and anywhere else they tend to collect. Adding fallen leaves to your compost pile is a great idea and is far easier than trying to bag up or cart off a large amount of leaves. Adding an organic fertilizer as a nitrogen source will hasten decomposition. Turn your pile once in a while to aerate. A properly decomposing pile will warm up to over 140 degrees and effectively kill insects, diseases, and weed seeds, that may be present. Next spring, you will be rewarded with leaf mold, an excellent soil amendment or mulching material.

image of a ladybug     Cold, drying winds in winter can cause leaves on evergreen plants to dry out and die. Leaves turn yellow at first, then brown. When temperatures fall below freezing and the soil is dry, the root system is not able to replace the water lost through the leaves. Cells in the leaves desiccate and die. Sometimes twigs and whole branches can perish. Many plants are susceptible: conifer, including arborvitae and junipers, and broadleaved evergreens, including boxwood and rhododendron.  Groundcovers like pachysandra, which are now exposed to full sun after trees drop their leaves, can suffer leaf and stem damage. Once the leaves have been damaged by windburn, they will not recover. To prevent this burn, water them well when temperatures warm. Provide wind breaks if possible.

image of a ladybug     Winter is a great time to reduce the bagworm population, decreasing damage next summer. Eggs of the bagworm moth survive the winter in bags left on the tree. These bag, which are 1 to 3 inches long and hang from the branches, are easy to spot, especially on deciduous trees including bald cypress. Check your evergreen conifers as well. Pick off the bags and throw them away. Each bag contains 500 to 1000 eggs, so removing even a few can significantly lessen the injury next year.

image of a ladybug     Forced air heat during winter resulting in very low indoor humidity can cause houseplants to suffer. Do not allow them to dry out, as they will be more susceptible to mite damage. These pests suck sap from leaves, which destroys the chlorophyll, resulting in yellow, stippled leaves. Heavy populations form silky webbing on the undersides of the leaves. Under favorable conditions, one generation time is only a couple of weeks, so populations can increase rapidly. Check for mites by holding a white sheet of paper underneath a branch and tap on the branch. Small, specks, the size of a period, will appear on the paper and begin to crawl around. A good spray of water will reduce a mite population. This shower will also reduce the dust accumulation on the leaves, which in turn, will increase photosynthesis.

Pest Management Tips Home

The best way to manage pests is to use a combination of chemical and non-chemical control. Only take action when the problem is serious enough to damage the plant. If we all use Integrated Pest Management (IPM), we can control pests in an environmentally conscious manner.

 Back to the Arboretum Home Page
Arboretum Information || Events & Education || Gardens & Horticulture || Research Activities
Support the Arboretum || New Plant Introductions || USDA Plant Hardiness Zone Map || Comments
Search Our Site

Last Updated   June 11, 2009 2:52 PM

Please address any comments or questions regarding any portion of this web page by e-mail to the FNPRU site administrator