NDSU Extension - Griggs County


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October 12

The Extension Connection


By Megan Vig


Snow won the race of who landed first this fall, while fall foliage still remains on the trees, for the most part.  As you watch for the fall colors hitting the ground, you might also notice needle drop.  This week I share information from NDSU Extension Forester Joe Zeleznik on fall needle drop in conifers. 


During autumn, deciduous trees like green ash and linden change color and lose their leaves.  This is normal and expected.  It happens every year and people are used to it.  When needles of evergreen trees turn brown and die, it’s definitely unexpected, but not necessarily abnormal. 


There are several species of evergreens, or conifers, that are frequently grown in North Dakota.  Pines and spruces are most common.  Pines have relatively long needles (2 – 9 inches) which are held in clusters called fascicles.  Scotch pine trees have two needles per fascicle, about 2 – 4 inches long, and they are usually twisted around each other.  Needles of ponderosa pine are in bundles of two or three (usually three) and are 4 – 9 inches long.  These needles live for 2 – 7 years, and then die and drop during the fall.  These are the older needles towards the center of the tree. 


Another common group of conifers are the spruces – Colorado blue spruce and Black Hills spruce.  These trees have shorter needles, about ¾ - 1-inch-long, and they are attached to the stem individually, not in bundles.  Blue spruce needles are pointier, or sharper, than those of Black Hills spruce.  Spruce needles usually live longer than those of pines, and may persist for up to 10 years.  Just like pines, the needles which are older and more shaded will turn brown and drop during autumn. 


So some needle drop by conifers during the fall is normal.  The exception to this rule occurs with larch trees (also called tamarack).  Larch trees lose all of their needles, every year.  They are deciduous “evergreens”.  Larch needles are 1 – 2 inches long and borne in clusters on short shoots, and individually on long shoots.  They are very soft.  Some larch trees are native to the swamps and bogs of northern Minnesota.  A common larch in North Dakota is the Siberian larch, which can tolerate the severe winters.  Larch needles often turn a bright yellow color and in the bogs provides a golden rain during autumn. 


Evergreen needles don’t last forever.  Some needle loss towards the center of the tree, during the autumn, is normal.  Needle loss at other times of the year is not normal and may be due to an insect or fungal pest or is the result of severe environmental stress.  And larch trees, the exception to the rule, lose all of their needles every year.  Enjoy the fall colors that still remain!


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