This article originaly appeared in “Florida Bonsai” the magazine of the Bonsai Societies of Florida.
VOL XXXV NUMBER 2 ISSUE 146
Reprinted with permission of the publisher of “Florida Bonsai” magazine.
Attack of the killer mites
Warning: This article has not yet been rated and may contain depictions of violence, crawly things and yucky stuff. It may not be suitable for the embarrassingly squeamish. Parental supervision is not advised, kids tend to like bugs.
“You’ve got mites.” No, not you personally. That’s what they’re saying about the juniper that you’ve brought in to a club meeting. Of course, you’re in immediate denial as the declarer calls out for a sheet of paper to prove your malady. However, what is even scarier than the possibility of mites is the enigma of where all those sheets of paper appear from. Say the word ‘mites’ at any bonsai club meeting and a slip will materialize from thin air. If you were stuck on an island with just your juniper and ten other bonsai enthusiast, someone would say, “You’ve got mites,” and immediately a perfectly clean, unfolded sheet of plain white paper would materialize so they could prove it you. Penn and Teller have nothing over some bonsai hobbyist and their blank pages. I don’t know about you, but stuff like that frightens me.
So you watch as they abscond with your plant and begin to shake it over that mysterious slip of paper. If you’re lucky, they don’t beat your poor tree to death. But do beware; these people may be more dangerous than the mites. After some prescribed time, or when they feel they have sufficiently dislodged enough material to show you, the spontaneously appearing leaf of paper is suddenly under your nose, and someone is shouting, “See! SEE! SEEEEEE! I TOLD YOU!!! Do you see’em? See’em? Do you see them RUNNING?!”
Afraid of being the only one who apparently doesn’t see them, or more probably out of the fear of those who are seeing these things scurrying about, and are getting so maniacal about it, you mumble, “Uh, yeah, sure.”
“You better get rid of them. You better get them under control – UNDER CONTROL! Yep, you better get them under control,” they implore, “or they’ll kill your plant!”
Kill your beautiful juniper? You snatch it back protectively and begin looking for an opening to escape from these crazy people with their sheets of paper and things you can’t see.
(Warning: One of those icky scenes not for the timid is about to be recounted. You may want to momentarily turn away. Don’t say you weren’t warned!)
“Just look at them!” they command of you, and even though you know you shouldn’t, like an accident on the freeway that you can’t turn away from, you look. “Watch this!” And they drag their finger across the paper, apparently over some tiny alien bodies that you were previously unaware of. Smudges of something appear on the paper. “Look at them smear,” they cry gleefully. (Icky scene over: You can look back now.)
Who are these nuts, and why would killing some microscopic bugs amuse them so? Should they be feared? Is this condition contagious? And, what about those smears? There was something there after all – something that was living and feeding off your plant. How do combat something you can’t even see? It’s like a scene out of a bad sci-fi movie.
Well, we’re glad you asked, because mites are serious business. (Can’t you tell?). But, before we can tell you what to do about them, you need to know just what it is you’re combating.
First of all, mites aren’t bugs. To be bugs they would have to be insects, and they’re not insects. Mites are arachnids. They’re related to spiders, scorpions, daddy-long-legs, and ticks. This is an important thing to be aware of because if you aren’t aware of this and its implications you’ll end up doing more harm than good. Even people who are aware tend to ignore the meaning and proceed with actions that they should know won’t be beneficial to their plants or surroundings.
A lot of different critters live in your garden, and, contrary to your fears, most of them probably do more good than harm – at least the ones you can see. You’ve got birds, reptiles, snails, insects, mites, and a million other things living out there. Now, you wouldn’t spray your plants with insecticide to keep squirrels off of them, would you? You wouldn’t spread diatomaceous earth to keep raccoons out of your yard, would you? Well, you shouldn’t be spraying insecticides to keep mites away either. Insects and mites are physiologically very different. Insecticides won’t have any effect on mites, and even those insecticides that claim to be effective against mites have such a weak or diluted miticide component that they’re more likely to just increase resistance in the mites than have any real benefit. These sprays, and the even more powerful miticides, have no effect on the eggs, so if you ignore everything here and spray, be prepared to be doing so constantly until the mites are under control, and then be prepared to continue this regimen when they recur. What you are more likely to do is to kill off any beneficial insects that would see mites as a nice snack. Too many people spray way too much, and end up killing desirable insects.
Real miticides are only available to licensed applicators, so chances are you won’t be able to get them. Miticides are also very, VERY toxic. You really shouldn’t be messing with them. You should be more worried about what miticides can do to you than what mites may do to your plants.
Having said that, if you live in Florida, and you have junipers, then you’re going to have bouts with mites. Just look at some of the common host plants of spider mites: azalea, camellia, citrus, silver thorn, hibiscus, ligustrum, pyracantha, rose, viburnum, juniper, arborvitae, holly, wax myrtle, and croton. And another group of mites (the eriophyid mites) attacks black olive, podocarpus, boxwood, maple and citrus, in addition to junipers. Don’t you think that there are more than just a few of these plants in your community, or yard, if not in your collection? Mites are just a fact of life for us, and acceptance of that fact is certainly the first step in dealing with them. They are never, ever going to go away – unless we can get some of those crazy people to run around with tons of copier paper shaking every plant in sight and then shipping those reams to some far away place like the Moon or Mars, but then that wouldn’t be very environmentally friendly to those other worlds, would it? We already litter our own planet enough.
So if mites are always going to be around, how are we to deal with them? Well, most of you have probably heard of the remedy of hitting your plants with a jet of water, especially on the underside of the foliage where the mites live. You’ve heard it, but do you use it? A method is only effective to the degree to which it is carried out. Since mites are always around, it needs to be part of your routine to make sure that you give your plants a nice shower to keep them off.
Something else thing you can do is place your plants properly. You know that you’re supposed to provide plenty of space between your plants so that they receive adequate sunlight and airflow. Airflow is very important in preventing many pathogens and pests. Also, when placing your plants, don’t group them! This may be one of the most important actions you can take in preventing problems. Commercial nurseries have to group their plants all together by species and variety because otherwise they would have an impossible management task. It also explains why they have to spray so much and why they can sometimes get wiped out by a pest or disease. Once a pest finds an appropriate host, it is very easy for it to spread from one plant to the next. Don’t place all of your junipers, or buttonwoods, or black olives, or any-thing else all together. If you do, you may as well be putting a bulls-eye on your plants. The pests will certainly zero in on them. Don’t make it easier for the bad guys.
There are some environmentally friendly solutions like ladybugs and predatory mites; however, they probably aren’t going to be of much benefit to the hobbyist, and the cost to benefit ratio is bound to be lousy, as much as I wish I could recommend them. Lady bugs have a tendency to travel, so even though they can be of amazing assistance against a wide range of pests, once they feel like they’ve done their job, they’re off. Predatory mites may be a better choice because they will hang around better. And as we already know, they’ll always have victims here in Florida. But, predatory mites will die off between infestations so they’ll need to be reapplied when mites reappear.
There really aren’t many other pests that we should have to contend with when it comes to junipers here in Florida. They can get scale, but I’ve never had a problem with any on junipers, and in some areas of the country bag worms are a problem, but we don’t have a problem with them here on the southern end of the state. Most of the junipers we use for bonsai here in Florida are the most resistant to pests and diseases. Both Eastern Red Cedar – Juniperus virginiana – and any of the chinensis varieties are very resistant to pests and disease. You will probably be more dangerous to your trees than anything else they will face, but if you take care of their watering needs and address potting/soil concerns, then your plants will not have to fear you either.
One final note on junipers and mites – when you water your junipers, notice the wet foliage. Healthy foliage will have a nice green color, whereas mite damaged foliage will be a drab gray color. The difference really stands out when the foliage is wet.
Take two fertilizer pellets and call me in the morning.
Junipers aren’t susceptible to very many diseases, and since we don’t generally grow apples or crab apples the list is even shorter for us. Cedar apple rust is a disease that requires two different hosts to survive. The disease lives half of its life on one host, and is then transmitted to the other. It is then transmitted back, and the cycle continues. One of those hosts can be junipers, and the other one will be a plant from the rosaceous family, which includes apple, crab apple, and hawthorn. The disease is actually worse for the host from the rosaceous family than the juniper. It will create galls on junipers. If you have hawthorn and juniper in your collection then you could technically have the hosts for cedar apple rust to survive, but this disease should not be a problem for us here in Florida.
There are three diseases that do affect junipers here in Florida. Again, we are fortunate in that the junipers we use for bonsai are the most resistant to these diseases. Also, healthy plants are much less prone to any of these diseases. The junipers we use that are most prone will be any of those with ‘Blue’ in the name, and any progeny of Rocky Mountain Juniper, Juniperus scopolorum.
The first disease is cercospora needle blight. This disease often resembles mite damage except it starts on the lower interior foliage nearest the trunk. As it progresses, it will move up and out on the foliage. The appearance will be of a tree that only has foliage at the tips. When the disease has advanced, the plant will also have the appearance of a tree that has been scorched by fire. If you’ve ever seen trees that have survived forest fire, then you know the appearance I am talking about. Eventually the tree is consumed and dies. Blue Vase is prone to cercospora.
The next two diseases are phomopsis and kabatina tip blights. Although they are two distinct diseases, the appearance is the same. Both diseases attack the newest growth on junipers. Older growth is resistant. The new shoots will turn reddish or brown. The will be an obvious demarcation between sick and healthy growth. With tip blights, removal of the affected tissue, and at least an inch or two beyond is necessary. This will help in preventing the additional spread of the disease. Once the discoloration is noted there is nothing that can be done. Do not fool your-self into thinking the affected part of the branch can be saved. Remove it immediately.
All three of these diseases are fungal based. When the damage is noticed, death of the affected area can occur very quickly from the time the plant is infected, although the disease may remain dormant for some time until it manifests itself. Since there is no treatment other than to prevent the continuing spread, prevention is the best course.
As already stated, treatment should include removal of affected tissue and in the case of phomopsis and cercospora, a copper based fungicide, Bordeaux spray, or mancozeb can be used. There is no treatment for kabatina. The good news is that prevention is possible and effective, and that these diseases do not have to be plant killers. These few rules really do make a difference. Remove dead foliage when noticed. Don’t prune your plants during the rainy season if possible, and not when the foliage is wet. Do not shear your plants. This is asking for problems and is not conducive to attractive or well styled plants anyway. Water your plants earlier rather than later in the day. Keep the areas surrounding your plants free of debris.
You have more influence on the survival and health of your plants than any pest or disease will have. Most problems are environmental – meaning you, since you create the environment. Water, feeding, placement, pruning, soil, and potting are the most influential factors in your plants health and are all things that you control. Healthy plants, especially junipers, are very resistant to any attacks by pest and disease.
Learn all there is to know about the plants you grow. We are fortunate to live in an age when there is so much information and data readily available. All the answers in the world are available to the inquisitive and those with a thirst for knowledge. All major universities have wonderful sites that have a wealth of reliable information. Share your knowledge with others, and they will share with you. That’s what clubs are supposed to be all about.
Speaking of sharing knowledge, I know many of you have the talent and knowledge to contribute this to publication and/or your club’s publication. So sit at the keyboard, or get out your pen, and start writing. So many of you have so much to share on so many topics. Many of you could add a ton of wisdom to what I have written, so get to it! Don’t make me start naming names! I look forward to your articles!
As always, I welcome any feedback.