I have a huge California willow tree in my yard and have noticed a hole the size of a basketball. The hole is near the base of the tree approx. 5 inches from the ground. There are ants crawling in the hole but no other insects that I could see. There is something that looks like sawdust but not a lot of it. Is this something I should be concerned about?
I would recommend having the tree inspected my a qualified Arborist.
You need to determine if these are carpenter ants, as they could damage the tree beyond repair.
Have a small weeping willow that was here when we bought the house. It had never been pruned so I did it. Now I have something invasive growing out of the tree with wide broad leaves! Also looks like sap or something is seeping from the tree.
Pruning during active growth will result in a tree bleeding sap.
Suckers should be pruned from the tree as soon as they appear.
Watch for signs of stress, pests and disease in the tree. Treat any pests with Neem Oil.
This link will refresh you on proper pruning.
https://www.gardeningknowhow.com/ornamental/trees/willow/how-to-prune-willow-trees.htm
I have three indoor cats and I would like to have a curly willow plant in the house. Is it a safe pet friendly plant?
Ah... the corkscrew willow! One of my favorites... It does contain salicylic acid, which is related to aspirin. The cat may dig in the pot, as they typically do, but this poses no threat to the animal. It is so bitter that the cat won't want to eat it after one taste. Carry on, and enjoy the awesome tree!
type of plant / name of plant/ best ways to take care of it/ does it need special care?
This might be a Salix matsudana, a type of willow. Varieties of this species with especially twisted branches are known as Corkscrew Willow. Here is more about its requirements:
http://www.public.asu.edu/~camartin/plants/Plant%20html%20files/salixmatsudana.html
I have a three year old globe willow tree that was doing just fine. This year the tree has yellow and very few leaves. We have watered it two to three times a week and applied fertilizer but there is no improvement. The tree is in desert calcareous soil type. What can I do to make it produce more leaves?
Definitely keep it watered, as willows tend to like being, constantly moist.
Now, I would not fertilize it very often at all. Adding dolomite lime will help keep the areas pH buffered, but adding that much fertilizer will likely cause the leaf drop to get worse. I would have to guess that it just needs as much water as possible. Keep the area moist.
Here is something that will help you:http://aces.nmsu.edu/ces/yard/2008/080208.html
My willow is oozing a white, foamy substance from its bark....What kind of care should I be taking?
This sounds like bacterial wetwood, aka slime flux or alcohol flux. Willows are prone to this disease. Bacteria produce gas which makes the sap foamy and often foul-smelling. Check with your state extension service for recommended treatment in your area. Here is what New Mexico extension has to say on the topic. http://aces.nmsu.edu/ces/yard/2000/081200.html
Can I put compost or dirt in it, or would that damage it?
Doing so would bring in a multitude of problems, such as pest and fungal infections. It would not be wise to do so. If you still plan to use this, you will want to water with 1 part peroxide to 3 parts water often to fight off any infection. Really, though, I do not recommend doing this.