Field Notes: Pine Yellows

December 17, 2018 2:00 pm

by Senior Area Forester Joe Rosetti

Every year, about 4-8 weeks after the deciduous trees lose their leaves, the pines of Virginia display a condition we will call Pine Yellows.  Pine Yellows is characterized by about half of the needles on the seemingly healthy trees turning yellow, then after 1-2 weeks falling off.  The trees do not display any other signs of disease or insect damage, and except for the changing color, appear perfectly healthy.  Upon closer inspection, you will see the needles that are turning yellow are only on the interior of the tree. The needles at the ends of the branches are staying green.  The yellow needles come off easily when pulled or brushed.  If this describes pine trees near you, then fear not.  Pine Yellows is perfectly normal.

pine yellowtall

Pine trees, along with spruce and fir, are evergreen, so it’s generally thought they keep their needles forever.  However, the trees needles are their leaves and leaves don’t last forever.  The needles you see turning yellow and falling off now are the needles that grew in the spring of 2017.  Every spring, the trees grow their branches longer and grow new needles at the ends of the branches.  They keep the previous year’s needles and grow through the summer with the needles from this year and last year.  When fall comes, last year’s needles fall off (resulting in the condition Pine Yellows) and the trees go through winter with the needles that grew this spring.  So in our case, the needles turning yellow now are the needles that grew in 2017.  The needles staying green grew in 2018, and they will stay through the winter.  In spring of 2019, the branches will grow and grow new needles, and the 2018 needles will turn yellow and fall off in November of December of 2019.

So if your pine trees are displaying Pine Yellows, don’t worry.  You can rest assured it is perfectly normal.

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