Learn About Bamboo
Bamboo doesn’t have many pests, but the pests they do have can be unsightly, if not a serious problem, unless some simple steps are taken.
Gophers: In Northern California we have an abundance of gophers and squirrels, who think tender new rhizomes, bamboo shoots, and even new branch buds are a delicacy. To protect the rhizomes from gophers, the best solution is to plant inside of a ¼ inch mesh metal gopher basket (which can be purchased). By the time the basket has rusted away, your bamboo is usually large and well established, and gophers cannot do enough damage to seriously harm your bamboo. If you find that new shoots or new branch buds are being chewed up by squirrels or gophers, painting them in hot sauce is quite effective! (It may leave permanent stains on culms, however.)
Deer: Bamboo in the western US is a deer-proof plant. We have lots of deer here in Northern California, specifically the western mule deer, but have never had a problem with them. However, if bamboo is the only fodder for miles around they might eat it, especially tender new plants; in that case, deer fencing around your new bamboo plants is a good idea. In the eastern U.S., the white-tailed deer co-evolved with the one native American species of bamboo, Arundinaria gigantea, and developed a taste for bamboo; therefore, deer fencing is more imperative in the eastern states.
Insects: Mites, Aphids, Mealy Bugs, Scale, & Ants: It is much easier to keep mites out of your bamboo than it is to get rid of them once they have established themselves, and they can become a serious problem. Therefore, inspect any new bamboo you import into your garden. If mites are found, immediately separate the plants from other bamboos in your garden and clean thoroughly with a high-powered hose. See below for stronger measures, if required. Also, mites live in grass, so if you are having this problem, make an effort to keep grasses away from the base of your bamboo.
The symptoms of mites are small, regular, bleached-looking spots on the leaves. If you look very closely at the underside of the leaves, you will also see a very fine white web. The mites themselves are silvery grey and so small it is hard to see them without a magnifying glass. Often mites and aphids can be found together, and the treatment for both is the same.
Aphids are small crawling insects, either green or black in color. Mealy bugs appear usually in branch joints as little spots of “white cotton” which seem not to move at all. Scale looks like little, flat cones on branches and leaves, and are light colored when young, growing darker and more visible with age.
Aphids, mealy bugs and scale all produce a sticky secretion which is eaten by ants, and often you will see the more mobile ants first. Ants themselves do not harm bamboo, but an unsightly black, sooty mold also grows on the insect secretions; the presence of ants or sooty mold is often a sign of other insect problems.
Areas that receive hard frosts in the winter usually don’t have big problems with mealy bugs and scale.
Treatments for Insect Pests
With the interests of the environment in mind, below you will find our approaches to insect problems, with the most environmentally friendly listed first.
Pressure washer and water: Every week or two blast the entire bamboo plant, paying special attention to areas of dense foliage and the underside of leaves. This can be very effective against mites and other insects, and will not harm the leaves.
Insecticidal soap: We use Arm & Hammer laundry detergent (powder), using 1 tablespoon per 1 gal water in a pressure washer or hand sprayer. Apply no more than once every two weeks. It turns leaves somewhat yellow, but is our treatment of choice because of its high effectiveness and low toxicity to the environment.
A note about potted bamboo: Ants are more likely to take up residence in potted bamboo, and an easy remedy is to simply submurse the entire plant in water for a number of hours to drown them out.
If the above methods are not sufficiently effective and you have a large area of infested bamboo, you might consider the following, more drastic measures or toxic substances:
Neem Oil: Organic insecticide which kills mites, aphids, mealy bugs, white flies, and other insects. Follow directions on the bottle, including all safety precautions. (Other “ultra-fine” oils can also be used.)
Merit .5 Granules: A systemic, soil based insecticide granule that will need to be reapplied annually. Generic version is also effective. Best where spraying is not feasible.
Avid: Kills specifically only mites and leaf miners, no other insects or birds. Has some systemic action, which makes it more effective with mites. Its very expensive and hard to find in retail stores. Follow directions on the bottle, including all safety precautions.
Malathion: WARNING: Kills bees and many other beneficial insects, birds and fish, other aquatic life. Follow directions on the bottle, including all safety precautions. Not recommended.
In very severe mite infestations of very large and dense groves, it is sometimes necessary to mow down the entire grove and dispose of the foliage and canes. If this is done during the rainy season, the grove will usually re-shoot the following spring, albeit with smaller canes than the original ones.