Hi Jeff...i have this book too, and i did that with all my palms at home and at my customers near Montreal. With my experience, its better to spray all the leaves with the fongicide/bactericide. Use the powder mixed with water and spray. I did spray only the crown last winter and i had 1 Trachy ( i had 12 palms outside last winter) with a fongic problem on the leaves but not in the crown. So i think if we spray all the leaves, we wont have this problem.
I think its maybe the mushroom spore in the air during the summer stay on the leaves during the winter, and inside the protection cage, we don t have ventilation. So thats the perfect environment for the spore, thats cause the fongic problem. If we spray all the leaves, we will kill all the spore before closing the cage.
Thats my way to see that....

Ben

Thank you Ben, on closer reading of the book, he says that its essential, I just found that tonight. It's a great book!

Would this be effective?
http://bloggingherbman.typepad.com/tips/2011/03/safe-homemade-fungal-sprays.html

If you open the cover once in a while-letting moisture out- you don't need it.

I would not spray any type of oil in the crown any time of year.

I don't use fungicide on my palms until they have pulled and then only
down the hole where it pulled to help it stay dry.

Jim, im agree with that. But for me, i have a lot of palms to protect at my customers. So, i dont ask them to open the box once a week or two. I dont really have choice to shoot them. But while using a arbotex covering the palm, thats help the leaves to stay more dryer.
Ben

Bacteria is usually the cause of rot after cold. You'll need to use fungicides that double as bactericides such as copper.

Bacteria is usually the cause of rot after cold. You'll need to use fungicides that double as bactericides such as copper.

Thats what I pepper the blow hole with(just drizzle a little copper f powder),it keeps the core dry so the damage doesn't spread.