Using Predatory mites to control plant-eating mites
As a palm grower I have always hated to hear that many interiorscapers tried to limit the amount of palms they were using because of spider mite problems. I would like to offer a solution to mite problems that is so effective, that those who try it will actually prefer to use palms on their accounts! This new method of mite control is known as biological control and take it from a grower who has used pesticides; it works much better than any chemical!
This method of biological control was introduced to me by Dr. Jeff Brushwein who is the head consultant for Florikan Company in Florida. Florikan has been a dedicated pioneer in biological control in Florida. They have invested a lot of time and money into seeing that the bio program works by having a qualified representative working with their customers to insure that the program works. This personal touch really makes a difference in bio-control as I will explain because this is a very different way of controlling pests and becomes an integral part of growing.
Interiorscapers know how well Chamaedorea (Bamboo Palm),and Neanthe Bella (Parlor Palm) perform in low light. The problem has always been controlling mites. Contrary to popular belief palms do not spontaneously generate spider mites. The mites, actually find safe haven in their protected homes which we keep guarded for them with chemicals.
Palms grown using miticides and insecticides have no natural predators living on them to kill off the plant eating mites. If we continue the chemical approach to controlling our insect problems, we must understand that we have no choice but to keep spraying. Worker Protection Standards and the Right To Know Act has made chemical control methods very risky for everyone. Where are we headed with our chemicals and why do we have to spray so much? The cutting edge technology is here and will be doubted by most until they try it. It’s nothing new actually; it’s called biocontrol and no posting or spray suits are needed to be in compliance with W.P.S. requirements. Best of all, used correctly it, works better than sprays.
Why are mites so difficult for us to control in the first place?
First, we know that Two Spotted Spider Mites and Red Mites are pests that love palms. Both species of mites can reproduce extremely fast and are capable of completely infesting a plant in 30 days or less. We also know that because of their fast life cycle they can develop a resistance to chemicals. Furthermore, it is hard to spray many palms effectively for mites because of the dense foliage mass and the fact that mites live under the leaves. Let’s assume we spray and kill all the nymphs and adults on a plant. Unless we have an ovacide, remaining eggs will be hatching any day. We are on a treadmill of endless spraying.
Now consider the natural mite predators that would normally exist on the plant if not treated with spray. These natural predators of the pest mites eat adults, nymphs, and eggs of the bad mites. They will lay eggs of their own when the food source is good and these eggs will be present to control the next generation of pest mites when they hatch. When we spray chemicals, we not only kill these natural predators, but many times the residues maybe toxic to predators for long periods of time; some up to 90 days. These chemical residues are the primary reason most people experience failure when trying predatory mite control programs for the first time. The residues from the old spray program cause predators to die or leave the plant, and zero predators equal zero control.
Two major problems today with the chemical approach.
The first problem is that for many years our industry (agriculture) has received bad press because of our use of pesticides and chemicals. The hazards of pesticides has been a popular issue on the talk show circuit. Many celebrities have been on the band wagon and have attacked our industry which has resulted in a negative image.The second concern is legal vulnerability. The government, whether we like it or not, has put into place the Right to Know Act and W.P.S. These new policies have created the vehicle to allow many people to sue others. Legally we should read every label on every chemical we use. Most labels require the applicator to wear boots, gloves, respirator, etc.
You may have heard that “The Land” at Epcot Center located at Walt Disney World Florida has been using biological control for pest management. A study was done in 1994 at the University of Florida on the Biological control of mites using Phytoseiid Mites by Drs. L. S. Osborne, J. Pena of U.F., F.L. Petitt, and Y. Q. Fan from “The Land” at Epcot Center. The results were fantastic! Pest mites were controlled using predators. This gave the program merit and caused many people to look at biologicals as a pest control measure. Lets meet the warriors.
More than One kind of Warrior!!!
There is more than one predator available for spider mite control. The most common predatory mite is Phytoseiulus persimilis. This mite is roughly the same size as the. Its body is red making it easily identifiable and has longer legs than the pest mites. They feed only on mites and will leave the plant after they run out of food and search wherever they can for other mites. None of these predatory mites have wings so do not worry about them flying around for people to see. The only way to really see them is to use at least a 10x magnifying glass. In other words don’t be concerned with the predators leaving a plant in search of more food; they are too small for anyone to notice.
Amblyseius fallacis is another predatory mite commonly sold for control of spider mites. This predator is brown in color and is said to have a voracious appetite equal to Phytoseiulus persimilis but has the ability to eat pollen. This is a great choice for plantings where pollen is available to keep the predators around.
Other commonly available predatory species include, Galendromis occidentalis, Mesoseiulus longipes and Neoseiulus californicus. Each predator has its own best application. Your supplier should be able to help you decide which predator will be best for your specific application.
Arrival and Deployment of your troops.
Predator mites are shipped on a carrier such as vermiculite, bran, or green leaves to make distribution easy. When a predator shipment is received; they must be kept cool and out of direct sunlight until released, which should be as soon as possible. When transporting from job to job, treat the predators like you would a pet. Remember that these are living organisms and will die quickly if left in a vehicle in extreme temperatures. All predatory mites are shipped in a styrofoam cooler with cold packs. This is an excellent transportation cooler. The actual application of predators is easier than any spray application. Simply remove the bottle from the styrofoam cooler/shipping container, and slowly rotate the bottle to mix them throughout the carrier. Do this for 30 seconds or so then unscrew the cap and shake out roughly one to two teaspoons on the foliage of the palm. As soon as predators contact the leaves they will run to find shelter. When moving from plant to plant it is necessary to hold the bottle horizontally and cover the opening of the bottle. If held vertically you will find that instinctively the predators climb up out of the bottle. This instinctive characteristic can be a tremendous benefit because they will also climb up the trunks of taller palms; no ladder needed. Keep bottles on their sides when storing or transporting also, because the predators will climb up into the cap and die from suffocation. These guys are not real smart so remember to watch out for their well being. When your bottle is empty leave it in a planting because, many predators are left crawling on the surface of the bottles.
Keys to success.
The two final keys to a successful predatory mite program is understanding that we need to out number the pest mites before they become a problem. For this reason routine releases every two to four weeks in plantings are most successful. If a plant happens to get badly infested with pest mites, a good insecticidal soap sprayed to knock down the major numbers a day or so ahead of releasing predators is a good idea.
This is more economical than buying enough predators to out number the bad guys however, it is not mandatory. You can clean up a severe infestation with a heavier release. Just remember that mite damage is irreversible so prevention is the goal. The second key is to think before you spray and think residues. Check with your predatory insect distributor for insecticides that leave the mildest residues.
Soaps are a great choice and do work if sprayed directly on insects because they suffocate and leave little residue. Check with your nursery grower to see what they have been using for insect control and remember some chemical residues are toxic to predators for 90 days.
If your grower has used a 90 day residual type chemical, control mites with soap or low residual miticide until you can make an introduction with predatory mites. If you are having problems with a particular plant the predators are not working on, chances are the problem is residues.
Understand that biocontrol takes time to work and that total eradication will not occur as quickly as it does with chemicals. Make sure to supply your technician with a 10 power loupe or magnifying glass so they can distinguish a good mite from a bad one. The same goes for identifying eggs. Talk to your predator distributor about what to look for and how to identify predators.
Realize that this is cutting edge technology and the future of all agricultural industries. We won’t always have chemicals to depend on and we need to prepare for it. Do some experimentation at home or in the office with predators until you feel confident with the program. During your experimentation, spray a plant or two so that you can compare how quickly pest mites rebound on chemically treated plants. Market the fact you are working with biological control. This is a great benefit to cover with clients at the time of bidding. This program does take a total commitment to achieve success but once you get the feel for it you will no longer worry about spider mite problems. So try a new approach to mite control and bring that lush tropical look back into the interior. There really is no substitute for the graceful elegance of a palm.
About the Author:
George Butler III is a second generation nurseryman specializing in top quality interior palms an foliage. He can be reached at http://www.butlersfoliage.com.
