P&PDL Picture of the Week for
March 12, 2007

Chlorosis of pine trees

Mike Mickelbart, Assistant Professor, Department of Horticulture & Landscape Architecture, Purdue University

Pines in this part of the country often struggle on our high pH soils. Many species of pine require soils with a pH around 5.2 to 6.0. Many soils in Indiana are 7 or higher. When the pH is this high, the nutrients required for healthy green growth in pines are not available. The result is slowed growth and, more noticeably, a yellowing of the needles.

Pine chlorosis is often more prevalent, or more noticeable in late winter/early spring. While it is not certain why this is the case, it is likely one of two reasons: Soil is often saturated during this time due to rains or snow melt. In saturated soils, there is not enough oxygen and the plant cannot take up the nutrients that is needs for normal growth. The plant is also preparing to grow. The new growth (still not visible to the naked eye) may be taking nitrogen from the older needles. This is common in many species, especially those that grow in “flushes” like pines do.

To avoid this problem, make sure that you plant species that are adapted to your soil (and other) conditions.

Click image to enlarge

Chlorosis on pine

Chlorosis on pine

Close up of chlorosis on pine

Close up of chlorosis on pine

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service