Questions regarding fall landscaping answered

RBC I When should trees and shrubs be watered to protect them over the winter?
In much of Northwest Colorado, winters can have extended warm, dry and windy periods causing winter drought. Trees and shrubs at risk from dry winters include disease and insect-infested trees. Examples include aspen suffering from canker or pine or spruce trees infested with beetle. A second area of concern includes mature trees planted in rocky conditions, recent transplants, evergreens and shallow-rooted species. Winter drought usually leads to branch die-back and leaf loss the following summer. The weakened condition often results in a larger chance of disease and insect infestations.
Monitor weather and soil conditions from November through March. Generally, if four weeks elapse without snow cover, water plants and trees again during these months when temperatures are above freezing and the soil is not frozen. Apply water early in the day so the water can soak into the ground before freezing nighttime temperatures.
One question often asked is how to water in the winter with frozen ground? Place several 1-1/2 inch to 2 inch PVC pipes about 18 inches deep around the tree. The most important area to water is from the edge of the branches halfway to the trunk. The pipe should be at ground level to avoid tripping accidents and capped. Watering can now occur below the frost level. Apply water at a slow rate to avoid run off.
Water plants when the leaves start to fall in the autumn to send them into winter with adequate soil moisture. For recent transplants, a soil needle can be used on low water pressure for one minute at each site to water the root ball and surrounding soil. Make injections in a grid pattern, one foot apart and nine to 18 inches deep. Frog-eye type lawn sprinklers can be used to water established trees and shrubs. Allow sprinklers to run 30 minutes at each setting.
Remember to disconnect and drain hoses after use. Don’t activate sprinkler systems during the winter.
Quite a few of pine trees in my neighborhood are showing a lot of yellow and brown needles. Is there a disease going around?
Interior pine needles of a certain age turn yellow or brown in late summer and early fall, then drop. This is normal. As long as this year’s needles are green and the buds are healthy, the trees will continue to grow. Pines retain their needles for different lengths of time before they shed them. For instance, Austrian pines shed their 4-year-old needles every year. Scotch pines shed 2-to-4-year old needles every year; Ponderosas shed those that are 3 years old; Pinon, the 4-to-5 year old needles and Bristlecones shed the 14-to-17 year olds. If several trees of the same age were planted at the same time, as might be the case in your neighborhood, their needle drop would always be synchronized, giving the appearance of a disease.
Caution: If more than one year’s growth of needles is cast, the tree probably is suffering from some type of stress. If the tree is turning red, it could be suffering from an insect infestation like Mountain Pine Beetle.
For more information on tree care, call Bill Ekstrom at 970-878-9490 or your local Colorado State Cooperative Extension office.