The most common problem diagnosed in November 2025 was affecting evergreens. The plants had yellowing and browning inner, lower needles (Figure 1). This is a natural process called seasonal or fall needle drop and it occurs each year from late summer to mid-fall. The process commonly affects pine, spruce, fir and arborvitae plants.

Figure 1. The inner and older needles on this pine tree in Oklahoma county are yellowing and browning due to seasonal needle drop.

Note that only the interior (oldest) needles are affected and needles near the tips of the branches are green and healthy (Figure 2). Trees that have suffered from environmental stress (especially drought) may show more dramatic needle drop than plants that have not been under stress. If new growth or outer needles are discolored, this suggests a different problem possibly caused by a pest or plant disease.

Figure 2a. This row of arborvitae plants has browning interior needles due to seasonal needle drop.

Figure 2b. A closer image of the brown needles.

No management is needed for seasonal needle drop. If unsightly, the needles can be removed by raking. However, leaving the needles on the ground under the trees provides a natural mulch that retains moisture, suppresses weeds and adds organic matter to the soil.

A summary of all submissions in November to the PDIDL by Oklahoma specialty crop growers is provided in Table 1. Look for an additional plant health update from the PDIDL in the next few weeks for our remaining 2025 submissions.  If you have suggestions for future topics, please contact jen.olson@okstate.edu or call the PDIDL at (405) 744-9961.

KEY for Diagnostic Testing Methods 

• DD - Digital Diagnosis
• M - Microscopy
• S - Serological tests
• C - Culture analysis
• N - Nematode analysis
• MD - Molecular diagnostic methods
• DS - DNA sequencing
• RS - Referral to specialist
• 0 - Other diagnostic tests