Botryosphaeria dothidea, (Nectria cinnabarina & Phomopsis juniperovora found only on Jack pine), Sphaeropsis sapineas, Leucostoma spp., Valsa spp. (Cytospora spp. conidal form of Valsa), & Scleroderris (Ascocalyx) are diseases of stressed trees. Several cankers cause the tree to bleed heavily, but others listed cause little if any sap to occur on the outer bark. All cause internal discoloration. Rainy wet weather helps in the spread of the diseases.
Control for most of these is to keep the plant growing well and minimize long-term stress factors on the pines. Prune out dead and dying limbs, water properly during droughts and feed in the fall when most deciduous trees are defoliating.
Written by James Schuster, Extension Educator, Horticulture, and reviewed by Bruce Paulsrud, Extension Specialist, Pesticide Applicator Training and Plant Pathology, University of Illinois at Urbana-Champaign.