Canker and Gall Problems

• Cankers and galls are swelling lesions on the wood. Sometimes they exude resins or saps, causing an unsightly look. Spruce Cytospora canker is caused by a fungus that kills off needles and branches, starting at the bottom of a tree. Cankers appear on branches, and the tree's resin turns somewhat blue instead of being clear. Remove infested branches prior to spring rains as water droplets spread the disease. Also, disinfect any tools used to cut branches as the disease is easily transmitted by using untreated pruning shears on another tree. The disease usually only affects weak branches, so prune off inadequate branches and prevent trees from becoming too crowded.
  
  Rust diseases produce galls caused by fungus spores. Cedar-apple rust attacks mostly junipers. Symptoms include swollen areas with an orange jelly-like substance that oozes, along with needle drop. Pruning affected branches is necessary. Pine stem rust is similar and not as severe. Control this rust by pruning all types of conifers, keeping the strongest branches.
  
  

Needle Problems

• Rhizosphara needle cast is a disease that affects spruce. Needles near the trunk turn brownish-purple and fall from the lowest branches first. The disease works its way up to the top of a tree. Chlorothalonil applied late May and July may stop the problem and save the tree.
  
  

Blight

• Diplodia tip blight strikes pine trees by stunting needle growth and turning needles brown. Small black objects grow from the needles, and the cones appear to have scales. Brown spot needle blight also affects and kills pine trees. Needles have yellow and red bands, and needles die and turn brown from the band to the tip. Fungicides containing copper can stop the blight. Apply them in May and again in July.
  
  

Rot

• Fungus enters a tree through wounds and decays the wood inside. The disease only affects conifers that already have problems. Root rot occurs when a tree has root injury. Symptoms include die-back of branches, discoloration of needles and stunted growth. Prevention is the only remedy that helps rot problems.
  
  

Pests

• Pine borers tunnel into the wood of a conifer and carry harmful fungus in with them. Symptoms are not found until it is too late, and insecticides do not work because the insect moves deep within the wood, where it cannot be harmed. Look for yellow needles that fall and for sawdust and small holes in the wood. Bark beetles and weevils affect pine and spruce. Beetles eat the needles and twigs of the tree and carry harmful nematodes that get inside the bark and plug resin ducts. Rodents eat the bark from trunks and lower branches, causing wounds where disease can enter to kill the conifer.