I have never heard of an outdoor bamboo having insect infestation problems like that. In fact, compared to other plants, bamboo is pretty bug-resistant, except for aphids and bamboo mites.W here do you live? Also, are you 100% sure this is bamboo? (There are a number of plants that resemble bamboo, but are not.) And, if it is bamboo, do you have any idea what species?

Insecticidal soap will help control the cause of sooty mold which is molds growing on the waste from piercing/sucking insects (homoptera). It will also help remove the mold itself when combined with a stiff spray of water. You may need repeat applications. Aphids seem to be more a response to poor culture conditions especially feeding high rates of nitrogen fertilizers which make for weak watery growth that they target. Homemade insecticidal soap would be swishing ivory bar soap in water until it takes on a bit of a gray appearance. Like any pesticide hot sun and pesticide together may be phytotoxic.

I've seen "companion" planting work, BUT it seems only if the milkweed is right in the middle of the repellant plant, not just somewhere around. In my example, I have a few milkweed plants growing in the middle of jumbles of lantana and gaillardia and the aphids for the most part leave those alone. But in that case I have to watch that the other plants don't completely overgrow the milkweed. I have to play milkweed hunt under the lantana and then cut away lantana so the MW can see the light of day, and of course, so the monarchs can get to it! Anyway that's my two cents.

Hi madhatten that is a cool plant and you should have no problem with it reaching 2" dia or up to 30 feet. It will probably take up to 6-7 years to do this with good growing conditions. Bamboo comes out of the ground the diameter it will be when it is full grown. It grows to its full height in 8-10 weeks. It will never grow taller or bigger diameter. Taller and larger diameter growth will come in subsequent years as rhizomes develope and are able to support the larger growth. I attended a growers conference awhile back. A question as to how much room do you really need for best growth and development was asked of a large scale bamboo grower in the SE US. His answer was that the rule was that if you had a bamboo that wanted to be 30 feet tall, you would need 60 feet of room for it's spread. If the plant was to top out at twenty feet, you would want to have 40 feet. This is why people run into problems when they plant it in a small space and walk way from it for twenty year. You can't put a barrier in the ground and expect it to be a forever solution! Concrete and rebar are your best bet for a narrow installation! Bamboo grows wood faster than trees! It's a great plant in the right place. Bend over and do the work pruning the rhizomes and you won't have problems