Western Gall Rust, (Endocronartium harknessii).

What's hurting my pine?

We get this question almost weekly because this pathogen causes many issues on our 2-3 needle pines, primary Ponderosa and Lodgepole. 

Western gall rust, (Endocronartium harknessii) is the culprit! 

This is autoecious (requires one host) fungal pathogen that attacks the branches and trunk of the tree, slowly girdling them and causing them to decline. It infects trees of all ages, can increase the likelihood of failure, and is difficult to control!

Trees with numerous galls can develop witchesbroom (masses of dense twigs), however in North Idaho branch and twig dieback are the most common. Secondarily, cankers such as P. contorta can develop (loci) at or near the woody galls. Most of the time it causes either sunken depression and bulging flanks (flat spots) in the trunk, or inversely, produce a hip canker, which can look like a burl or a big booty. These modifications to how the xylem (wood) forms can cause significant strength loss, making the tree much more likely to fail than others. 

Is it killing my tree?

It sure ain’t helping! Assuming it is just staying on the branch tips, the issue is moderate, but once it breaches the trunk, all bets are off for a long life. It’s actually in its best interest to keep the host alive, (just ask McDonalds). 

Keep in mind, many trees can live a long life while sustaining infection of the canopy, but one bad summer, lightning strike, or change in irrigation could be the last pieces of elk quarter on the alpacas back.

Trees usually die from multiple stressors compounding, and every cluster of needles or leaves a tree loses, the less energy it’s producing, as well as the negative atmospheres used to draw water up into the canopy. This makes it hungry and thirsty, even if sun and water is plentiful. 

Tree Maths 101.

Reduced Tree Transpiration = Increased Wallet Perspiration.

So how does it work?

The aeciospores (chalky yellow seeds of annoyance) attack the young succulent growth in the spring and hunkers down, eventually causing swelling and gall formation the next year, and even cones can become infected.

Usually 2-3 years after infection, the galls aecia (cluster cups) releases yellow/orange spores during low humidity weather 2-3 weeks during the spring, primarily when temps are between 60-85F. They hang out floating around until the rains come, and then they get their chance to stick! If conditions are perfect for the pathogen, trees can have a "wave year" which is essential a bumper crop of disease. AKA.... The trees get hammered.

Give it to me straight Doc.....

Prune them out and remove any tree within 300 yards that has it too. If pruning is done, the arborist MUST & SHALL disinfect their tools with a sporicide between each cut, or else they will just spread it even more. Cuts should be made 6” or more past the visible gall. (Many arborists try to help and make matters worse). 

As far as chemicals, there is not any real effective products at this time. Technically the trees could be sprayed with a copper-based fungicide twice a year, but it’s only cost effective for nursery stock.

Note:

This was learned, knowed, and typed by a real human being called Cody Willard, he is the primary human of Tsuga Treeworks.