Bamboo Mites
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Promoting the Beauty and Utility of Bamboo

Is there a Problem with Bamboo Mites?

by Gib Cooper

In the past five years or so I have observed a steadily increasing problem with expansion of the pesky bamboo mite. It may not be a problem for most bamboo growers. It’s not a pest that will come swooping down on your bamboo grove and defoliate the culms before your eyes. As far as I can tell from several years of experience this is a “classic pest” that is vectoring to new locations through the selling and trading of bamboo by nurseries, bamboo societies and friends.

When the issue is discussed between bamboo friends the problem is either minimized or exaggerated, depending on the relationship of the speaker to the pest. It is kind of like diseases and pestilence amongst humans. Who gave me that last cold? There is a stigma of blame associated to the giver of the unwanted problem. Well the fact is, the bamboo mite is another organism with a niche in the ecology of bamboo. They are prevalent in many areas and, if ignored, may prevail over your bamboo. You must be asking yourself the question: Where did I get that Sasa palmata? Does it kind of look like it is variegated? When the bottom of the leaf is carefully looked over one may see tell tale flat sheets of webbing scattered among the yellowish striations caused by the bamboo mites.

Identification

Bamboo mites should not be confused with the more common red or Pacific spider mite. These spider mites cause an overall microscopic stippling with yellowish centers throughout the leaf. When the underside of the leaf is viewed through a magnifying glass, one will observe loose webbing and mites moving around on the whole area of the leaf. The bamboo mite in a similar observation will only be seen within their webbed capsules located in the yellow striation of 1/8 to 1/4 inch or so width along the parallel venation of the bamboo leaf. The yellowish streak starts out small but gradually grows longer and spreads to other parts of the leaf and to other leaves in time.


 

Picture of bamboo mite damage

Typical Bamboo Mite Damage


 

picture of spider mite damage

Typical Spider Mite Damage


 

picture of scale damage

Typical scale damage


Mites are not insects but relatives of spiders. The mite sucks juices from the leaves, preferring the underside habitat to the topside. The adult mites are tiny. At 1/60th of an inch, one requires a 10X magnifying lens to observe their activities. The complete life cycle for mites is around forty days. According to Young and Haun in Bamboo in the United States, USDA Agriculture handbook #193, the more common red spider mites are of the genus Tetranychus. Bamboo mites are of the genus Schizotetranychus and somewhat resemble the red spider mite in appearance and make small white webs on bamboo leaves. The two bamboo mites listed in the handbook are the common bamboo mite (Schizotetranychus celarius) and the bamboo sheath mite (Stenotarsonemus phylloporus).

Handbook #193 describes the preferred host genera as Phyllostachys and to some extent, Pseudosasa for the common bamboo mite. This mite is confined to the leaf sheaths for a period of 8-10 months and is not found on the stems near the ground or in rhizomes or other parts of the plant below ground. It migrates in May and June. It is found in Florida and California. No serious injury has been noted in this country or Japan, its native home.

The above description appears to be close to the bamboo mite infestation currently observed by many people. It does not describe the complete and thorough degradation of the leaves of entire bamboo groves as seen by this observer. The preferred hosts seem to be the genus Sasa and Indocalamus with Phyllostachys, Pleioblastus and just about every other genus represented in this country capable of carrying this mite. Host plants seem to live fine with the pests. Perhaps, no more of a inconvenience than a dog with fleas. The main problem with infested plants is visual; particularly, the big leaved bamboos. The other problem is the movement of the pest into new regions by trading among bamboo lovers. We do not know how this mite can affect future attempts in bamboo agro-forestry production.

With many years of experience in the bamboo groves and nurseries of California, the author had not seen bamboo mites until a visit to the Pacific Northwest. The mite was first observed on a Sasa veitchii. The leaves were so discolored as to look variegated. The mite had practically invaded every stand of bamboo in the area. Now one can find the pest in many areas of California, Oregon, Washington and Florida. In other travels in the region many older established groves of bamboo were observed to be uninfested. In talking with bamboo owners of infested bamboo groves, the bamboo mites came from bamboo plants acquired from areas in the Northwest.

Recently, the bamboo mite has been recognized as a problem by the American Bamboo Society and several regional chapters. Jack DeAngelis, Oregon State University professor and entomologist, sent some information about the mite. Professor DeAngelis has experience with the mite, alias, bamboo spider mite, bamboo mite, common bamboo mite or more clearly, Schizotetranychus celarius. He refers to it as a pretty obscure pest. (Unless you happen to be a bamboo lover!) In a textbook of entomology, the native range of the mite is mentioned as the islands of Hokkaido, Honshu, Shikoku and Kyushu in Japan. In the U.S.A., they are found in Florida, Georgia and California. For some reason, Washington and Oregon were not mentioned as areas of infestation.

Control of a bamboo mite infestation in large groves or areas of bamboo may be difficult to attain. One possible control method, but personally untested, is to clear cut the bamboo and burn the debris. Begin and maintain a spray program on the new shoots. However, one could not be assured of success if the nearby neighborhood contains other infested groves. Other plants must be observed also. Bamboo mites have been collected from Ficus stipulata and sugar cane.

Controlling pests

The best opportunity to halt any future mite problems is to quarantine newly acquired plants. Although there are several bamboo nurseries with bamboo mites, there are some that are mite free. Owners of nurseries with mites will generally inform the buyer of the problem and, in some cases, make sure the plants are sprayed. Worry about bringing the pest home should not stop there. The plants should be kept away from other bamboo and resprayed about a week apart at least two more times. One must learn how to recognize the mite under a 10X hand lens. Once the mites breeding cycle is broken, then the bamboo may be judged safe to mingle in the landscape. This method of control is called exclusion or preventive control. Exclusion is the first and easiest pest control step practiced by seasoned horticulturists.

When there is a small mite infested area just getting underway, it may be practical to “spot control” using insecticidal soap or approved miticide. The liquid may be applied to the affected area using a spray bottle or tank sprayer.

The bamboo mite is particularly hard to hit with contact sprays due to the thick webbing barrier and the underneath position of the webbing on the leaves. Therefore, a miticide with systemic capabilities is more effective. The spray is absorbed into the plant and then poisons the mite as it feeds. This does not kill the newly laid eggs. Subsequent spraying at the right time in the mite life cycle will control the newly hatched mites.

Sprays containing oil are effective on bamboo mites. Karl Bareis, of Santa Cruz, CA, passed on information whereby growers remove about 80% of the bamboo leaves and spray with a new oil, which, if the temperature remains below 60 degrees F for the first five hours will cause no defoliation. One application of the oil kills adult, larva and eggs.

Most people are not eager to use poison sprays around the house. So great care must be taken when using these chemicals. It is best to check with your local nurseryman or extension advisor before deciding which spray to use. Always read the label very carefully and handle the product with caution.

Biological control is a desirable control method. Success with predator mites appears to be best in the greenhouse. Betty Shor has tried the predator mites, Galendromus helveolus, used in commercial avocado orchards and G. annectens on three occasions in 1993-94, on mite infested Pleioblastus, Sasaella, etc. in 1 gallon pots. The plants were in her yard in La Jolla and at Quail Gardens in Encinitas, CA. She concluded that the predator mites set back the infestation but definitely did not eliminate it. She observed that Pleioblastus viridistriatus did not become infested even when near infested plants. Other predator mites listed for control of spider mites are Phytoseilus persimilis, Metaseiulus occidentalis, and Ambyseius californicus. It is not known if other predator mites have been trialed by bamboo growers.

The 1994 Pacific Northwest Insect Control Handbook lists only two chemical controls for bamboo mites. These are insecticidal soap (Safer’s brand works well) and Talstar- 10 wettable powder. Talstar is a newly registered pyrethroid compound more active (toxic) than several now in common use. In addition, this writer has had highly effective results practicing exclusionary spraying with Avid on newly acquired plants.


Other Resources

Phil Davidson, of the Pacfic Northweast chapter, offers his homebrew recipe for mite spray.

Get an empty one-gallon milk container and add the following:

  1. two teaspoons of liquid dishwashing soap
  2. two tablespoons of any vegetable cooking oil, new or used
  3. fill remainder of milk container with water

This is your stock solution.

Fill your hose end sprayer (with a golf ball inside) and set for 2.5 oz per gallon. Spray for mites, thoroughly soaking the leaves, especially the underside of the leaf where the mites have their webbing.

Every 20 seconds or so agitate the hose end sprayer to keep the oil, soap and water in solution (this is where the golf ball comes into play)

You can vary your mixture. I sometimes use up to 4 oz per gallon with no burning or other ill effect on the leaves. I recommend starting with a lower dosage and working up.

This mixture will smother the active mites and 'melt' their webbing. I do not know or have studied what effect, if any, it may have on mite eggs.

Repeat every 2 - 3 weeks to kill any mites that may have been missed or newly hatched.

Advantages of this 'homebrew' miticide:

  1. It is safe! These ingredients are found in your kitchen!
  2. The mites cannot build up a tolerance to it as they are smothered by the mixture!
  3. It is very inexpensive. I estimate about 2 - 3 pennies per application.
  4. It is bio-degradable and breaks down quickly.

Note: once you are finished spraying ensure your thoroughly rinse out the plastic hose end sprayer with fresh water as the mixture of oil, soap and water will degrade the plastic making it soft, gummy and unusable.

Phil Davidson
Jade Mountain Bamboo Nursery
www.jademountainbamboo.com

 

Robin Rosetta of Oregon State University has put together a Web site explaining how to use Integrated Pest Management against bamboo mites. She describes the mite, the damage it does, recommends cultural, biological and chemical control and has some interesting pictures (I loved the scanning electron microscope pictures.) Following the links she provides, you can locate sources in the U.S. of preditory insects that prey on bamboo mites.

Dr. Jack DeAngelis, a retired entomologist formerly of Oregon State University, has created a Web site called Living with Bugs. He wrote to highlight a document on his site specifically about identifying and controlling bamboo mites.

Cornell University has a Web site about biological controls, in general. They say:

"This guide provides photographs and descriptions of biological control (or biocontrol) agents of insect, disease and weed pests in North America. It is also a tutorial on the concept and practice of biological control and integrated pest management (IPM). Whether you are an educator, a commercial grower, a student, a researcher, a land manager, or an extension or regulatory agent, we hope you will find this information useful. The guide currently includes individual pages of approximately 100 natural enemies of pest species, and we envision continued expansion. On each of these pages you will see photographs, descriptions of the life cycles and habits, and other useful information about each natural enemy.”


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