WE purchased 8ft tall white pine trees and watered them every day for 2...

Asked September 26, 2015, 7:28 AM EDT

WE purchased 8ft tall white pine trees and watered them every day for 2 months and then every oter day for about a month and now once every 10 days. Some of them have turned all brown and look dead. They are planted in a wooded area with large hardwood trees and some smaller ones. Did we not water them enough? We had purchased the same trees the year before and all but one died and we removed them and planted more this year. The person we bought them from said we did not water the previous ones enough but now I am beginning to wonder if it is not something else as we watered them a bunch!Can you help me?

Lackawanna County Pennsylvania

3 Responses

White pine is more tolerant of wetter conditions than red or jack pine, but less tolerant of dry conditions. Best growth occurs on sites with medium to fine soil texture, medium to high soil fertility, and a soil layer that is moist most of the time and deeper than 18 inches.

Avoid the extremes of heavy, continually wet soils and gravelly, drought-prone soils when selecting planting areas.

Unlike red or jack pine, white pine can easily tolerate growing under a canopy of other trees. White pines survive best and have better form when grown under taller trees because they are less susceptible to attack from white pine weevil and blister rust infection. However, if white pines are planted under a thick stand that allows very little light to reach the ground, they may grow very slowly or die. As a general rule, plant in areas that are 40 to 60 percent shaded from high shade (shade from low shrubs is not beneficial). Aspen, birch, and oak provide good canopies for young white pine, especially if the canopy trees are old and starting to die. White pines grow well under a thin canopy of larger trees.

Thank you for answering my question. If the needles are turning brown on the inside of the tree before the outer needles are, does that mean under watering? We are back to watering them daily. I am attaching 3 pictures so you can see what they look like. Please if you would let me know what you think.

Thank you.

Several things can cause browning needles on white pine. The most common thing is the natural browning, and dropping, of the older, inner needles. Needles that are 4-6 years old will yellow, then brown and drop in the fall.

It is normal for conifers to drop their oldest needles in the fall. This annual shedding occurs on all trees at about the same time, and always occurs in the fall. If this is the case for your tree, there is nothing for you to do. Just give the tree 'good care' by mulching and watering, as noted below under 'drought stress.'

An abnormal needle drop would occur in the spring or summer, affecting only one or a few trees, rather than all or most of them.

Another common issue is drought stress. Last year’s drought, and this year’s lower than normal rainfall in September, can cause the tree to brown and drop more needles than usual. Provide a 2-3 inch deep mulch from trunk to the edge of the tree’s branches (without the mulch touching the trunk of the tree); and slow, deep watering of the root zone all the way around the tree ( a soaker hose is a good way) during times of drought- be careful not to flood the root zone, especially if you have clay soil.

Poor conditions in the root zone can cause pines to lose needles early- and possibly kill the tree. Watch for compacted soil, standing water or flooding, cutting major roots, parking vehicles on the roots, etc.

Injury from de-icing salt also causes the death of white pine needles and branches. Symptoms from salt show up on the side of the tree closest to the salted road. Trees closest to the road are most severely injured.

There are needle blights that can affect white pine- here is a link to an article about blight. It was written for Christmas tree farmers, but the disease symptoms can be compared to your situation http://msue.anr.msu.edu/news/managing_dothistroma_and_brown_needle_blight_on_pines
If you think a disease is involved, you can confirm this a couple of ways. You can send a sample to Penn State via your local county extension.

Or you can consult a certified arborist, who will come on site, evaluate the tree as a whole, and give a diagnosis and a plant heath care guide. See www.treesaregood.com and click on the ‘Find a Tree Care Service’ tab at the top of the page. Contact 2-3 arborists and get estimates.