Submitted by Tokina McHarry, James River SCD Education/Outreach Manager
The most common question we receive this time of year is how much water do newly planted trees need? The following information was adapted from South Dakota Extension. There is no specific rule for watering – many factors are involved like soil type and rainfall patterns. But there are some general guidelines that will help alleviate the situation.
The most critical watering needs are for trees that were just planted this spring. These trees do not have a well-developed root system and regardless of whether they are planted bare-root, container or balled-and-burlapped, they will require extra attention to watering this summer.
A newly planted seedling needs between a pint and quart of water per day while a newly planted ornamental tree, one about 6 to 8 feet tall, needs about 2 to 3 gallons per day. Ideally this quantity of water is applied daily for the first couple of weeks following planting. The root system of these transplants is fairly small and larger quantities of water may flow away from the tree roots before being absorbed. It is also important to water directly next to the stem during this time period so the water is available to the tree, not the surrounding soil or vegetation.
Established trees do not need daily watering but will still benefit from weekly watering if the rains continue to hold off. A small windbreak tree, one planted a year or two ago, still needs about 3 to 5 gallons of water a week. A 2-inch diameter tree (measured at 6-inches above the ground) should receive about 20 gallons of water a week during drought periods. The best means of applying this water for landscape trees is slowly with a soaker hose placed near the tree. While tree roots typically extend out as far as the tree is tall, the critical watering zone is a distance out about 2/3’s the height. As an example, if the tree is about 12 feet tall, the watering should be done within 9 feet of the trunk.
The water should be placed on the soil, not the foliage. There is a common myth that evergreens absorb most of their water through the foliage. There is no truth to this as the root system is the primary means of absorbing water, the amount of water absorbed into the foliage is insignificant. While there is nothing harmful about watering foliage (it does not result in scalding), it is a waste of the resource.
If the rains begin to fall across the state, supplemental watering may no longer be needed. Trees generally need about an inch of water a week during the growing season. Watering trees during weeks of receiving an inch or more of rain may contribute to root decline due to the lack of soil oxygen.
Another reason to keep newly planted trees well-watered is that pest problems can increase as a result of long-term drought. Many pests, like wood borers and bark beetles, cannot survive in a healthy tree. As a tree or shrub becomes weakened from drought, these pests invade rapidly. Other pests that take advantage of drought-stressed plants include the bronze birch borer, black turpentine beetle, and many conifer bark beetle species.
Some pests, like spider mites, lacebugs, and aphids, can also be more detrimental to their hosts during extended hot and dry periods. The increased injury is a result of the plant’s inability to grow faster than the rate of damage, due to the lack of water. Also, many beneficial insects, such as predatory mites, slow or cease foraging activity under these conditions.
Once such insect pest that has been observed in greater quantity this spring and early summer is cottony maple scale. These soft scales are usually first noticed during the summer months when the female produces a conspicuous white egg sac, called an ovisac, that appears as a ¼- to ½-inch long ball of cotton. Heavy infestations can result in branch dieback and in rare instances, tree death. While common on maples, I have personally noticed this pest on my boxelder (in the maple family) and linden trees. Be cautious with insecticides because these will also terminate the natural predators. The best remedy is to keep the trees well-watered and healthy, and then there should be no lasting to harm to the trees.
Please don’t hesitate to call the Soil Conservation District office with additional questions and concerns regarding your newly planted trees.
Dates to remember:
June 14 – SCD Board Meeting, CBS’ Ellendale, 8 am
June 19 – Office closed, Juneteenth
For more information contact the James River Soil Conservation District and Ellendale NRCS office at 349-3653, ext. 3. Our field office is in Ellendale at 51 N. 1st Street. Also, remember to visit the James River Soil Conservation District Facebook page and our websites for more information –http://www.jamesriverscd.org/ and http://www.nrcs.usda.gov/wps/portal/nrcs/site/nd/home/. The NRCS is an equal opportunity employer, provider and lender.