Brown needles on pinyon pine

Asked June 10, 2016, 11:58 AM EDT

I planted last year and drip irrigate for 20 minutes 3x a week this time of year starting about a month ago. Soil is sandy clayish out here north of flagstaff. Good drainage. Lots of spring winds. Am seeing increase in brown needles but also lots of new growth. Whadyathink? Thx.

Coconino County Arizona trees and shrubs

1 Response

I have been on forestry tours in your area but am only vaguely familiar with the growing conditions. It seems like micro-climate could make a lot of difference in your area. Micro-climate certainly impacts wildfires around Flagstaff. Slope, aspect, temperature, air & water drainage all may vary in a small area (micro-climate) and those differences can impact plant survival. Pinyon pine is shade tolerant and grows best in arid conditions on gravelly slopes usually with scrub oak & juniper.

If the tree has new growth then current conditions are favorable for it. The brown needles could be the result of a soil problem (too much or too little moisture), or it may be the result of an insect pest / plant disease. Since pinyon pine is shade tolerant, it may benefit from a shade/wind barrier. This small barrier placed near the side of the tree is not to exclude wind and sun but to mimic the natural, partial-shade habitat it grows best in. At the elevation of Flagstaff it would seem like snow cover would be common during part of the winter. A lack of snow cover in an area with usual winter snow could reduce available winter soil moisture, especially on frozen ground. On the other hand abundant snow cover can result in sunlight reflecting off the snow onto the needles on sunny days. Intense winter sunlight reflecting off snow onto exposed pine needles can raise the needles' temperature and dry the needles. Winter conditions are important to most conifer trees because they often continue growing in winter.

Many variables here: best to try to provide a pine transplant with conditions as similar to its native habitat as possible. Finally not all species transplant well, and within a population of a plant species, like pinyon pine, not all individuals perform equally. Some individual plants are more or less adaptive to transplanting.