Disease Directory

    Pine Wilt Nematode

    Bursaphelenchus xylophilus

    Nematode
    Leaves
    Stems
    Whole Plant

    Overview

    A devastating nematode disease of pines transmitted by longhorn beetles. Causes rapid wilting and death of susceptible pine species, particularly non-native pines in Asia. Pine Wilt Nematode lives in soil and roots. Damage is often patchy. Rotation, resistant varieties, and soil health matter more than foliar sprays. Causal agent: Bursaphelenchus xylophilus. In regenerative gardens, prioritize sanitation, airflow, and unbroken soil cover over calendar spraying, and intervene early when symptoms appear.

    Symptoms

    Rapid wilting and browning of needles, progressing from branch tips inward. Resin flow ceases. Wood becomes dry. Tree death within weeks to months. Blue stain fungi often accompany infection. Compare several plants and note whether symptoms spread after rain, insect feeding, or wet foliage. Photograph undersides of leaves and cut stems when wilt is present to refine the diagnosis. Rule out simple drought, fertilizer burn, and herbicide drift before assuming a pathogen - abiotic injury often mimics disease.

    Environmental Conditions

    Hot

    Prevention

    Remove dead and dying pines promptly. Control longhorn beetle vectors. Quarantine wood movement from infested areas. Plant resistant pine species. Preventive trunk injection with abamectin. Mulch to reduce splash, clear season-end debris, and avoid working plants when wet. Design beds for airflow and diverse plantings that support beneficial insects without creating permanent humid pockets around susceptible crops.

    Management

    Remove and destroy infected trees before beetle emergence. Chip or burn wood. Trunk injection with abamectin for high-value trees. Vector control. Quarantine measures. Prefer drip irrigation, morning watering, and open spacing so leaves dry quickly. Disinfect pruners between cuts on woody plants. Use copper, sulfur, or biological products only as labeled protectants when pressure is high - they rarely reverse advanced infections alone. Destroy (do not casually compost) highly infectious debris.