Scots Pine Needle Blight: Questioning Soil Injection Treatment

A 40-foot Scots pine shows orange needles in no pattern. An arborist proposes expensive soil-injected fungicide with "50/50" success odds.

Likely Diagnosis: Brown Spot Needle Blight

Caused by Scirrhia acicola. Symptoms match: orange-brown needles, no distinct pattern. Standard treatment is foliar fungicide sprays, not soil injection.

Proven Spray Protocol

• Materials: Bordeaux 4-4-50 or chlorothalonil
• Timing: First spray at half-candle elongation
• Second spray: 3–4 weeks later if wet spring or severe infection
• Coverage: Complete foliage wetting essential

Critical Questions for the Arborist

1. What specific pathogen did you identify? (Lab confirmation?)
2. Why soil injection instead of foliar spray for a needle disease?
3. What fungicide will be injected, and what's its mode of action?
4. Can you provide references for soil injection efficacy on Scirrhia?

Recommendation

Request written diagnosis and treatment rationale. Brown spot is reliably suppressed with timely foliar sprays. Soil injection for needle cast lacks established efficacy. Consider second opinion from state forestry pathologist before committing to costly unproven treatment.