Profile: Nina ShishkoffNina Shishkoff at work taking leaf disks in the biosafety-level-3 containment facilityNina Shishkoff grew up in Michigan and studied botany at the
University of Michigan. She spent summers at the University Of Michigan
Biological Station in Pellston, MI, learning about native plants,
lichens, mosses, and fungi. She got a Ph.D. in Mycology from Cornell
University, and then wandered around the country doing plant pathology.
She now studies invasive pathogens for the Agricultural Research Service
of the USDA in Frederick, MD.
The following is an on-line interview with Nina ShishkoffAoB:
At the University of California, you studied diseases of tomatoes and carrots, at Cornel University, you studied diseases of pumpkins, and now at The USDA you continue studying plant diseases and pests. Your qualifications, experience, and interest in bonsai most likely makes you the foremost authority on bonsai pests and diseases; what led you to study plants and what led you to bonsai?Nina:
Actually, studying pumpkin diseases does not make you much of an expert in anything except pumpkin diseases. Right now I'm working on tree diseases for the USDA, and that makes me *kind* of qualified to answer bonsai questions, but I'm not a foremost authority.
Plants are cool! I got interested in them in high school after seeing the TV program "Nova". I majored in botany in college, and then got interested in fungi. When I was doing a post-doc at UC Davis, I went to the California State Fair and saw my first bonsai exhibit, and it was love at first sight. And I knew, whether or not I could make them pretty, I could at least keep them alive.AoB:
Do you think bonsai are more or less susceptible to pests and diseases than trees growing in landscapes or in nature? Why?Nina:
The biggest problem a bonsai has is stress: water stress from underwatering, too much heat, or too much wind. Unlike a tree in the ground, a bonsai has a limited root system in a shallow pot and may need water every day. In hot weather, that can mean a period of stress every day. Stress makes plants more susceptible to insect pests and diseases. AoB:
The Elm Bark beetle seemed to leave trees under a certain height alone, eliminating the threat for Elm bonsai. Are there other cases in which the size of bonsai was prevention against damage or does the smaller typical size of bonsai actually present a greater danger in most cases? Nina:
Yes- a lot of insects will ignore a small tree, or won't be able to "smell" a small tree. Chestnut blight only affects chestnuts when they are about 20 years old- I'm not sure if a 20-yr-old chestnut bonsai would be spared or not. Maybe I'll find out: a friend gave me a chestnut seedling.AoB:
Many bonsaists wait until there actually is a pest or disease problem apparent and then apply a solution, others swear by preventive spraying and other measures to prevent any possibility of a problem. Which method would you recommend?Nina:
If you have a recurrent problem- the way I have with pine tip moths- then prevention is the way to go. However, any time you make an unnecessary application of a pesticide, there's a risk of the pest controlled by that pesticide encountering it when it's wearing off. A few individuals may have resistance genes, survive the encounter, and pass on resistance genes to their offspring. Professional growers "scout"; they look for a pest problem, and only when it reaches a certain level do they spray for it, using several different methods to make sure that an organism resistant to one will be controlled by one of the others. That's the best way to do it. And it doesn't have to be a chemical method: I cover my pines with a fine netting during the pine tip moth egg-laying season.AoB:
In your opinion, does the use of inorganic soil substrates reduce the occurrence of many bonsai ailments?Nina:
Inorganic substrates start out clean, and can have good drainage and aeration qualities, so they are often very good potting media. Some organic media are infested with pests (raw soil from the backyard) and some will be inhibitory to pests (pine bark mulch). It depends. The main thing is to make sure the potting medium, whatever it is, isn't too heavy or too light for the tree, or the bonsai will get stressed.AoB:
Some bonsaists recommend the practice of using cut paste or other wound sealants on bonsai, claiming that these sealants prevent drying out and seals out pathogens and other harmful things. Others like the late Dr. Shigo, claim that sealants do more harm then good, claiming that using such can actual seal in pathogens and do more harm than good. What are your thoughts on this subject?Nina:
At Cornell, we believe that wound paste neither helps nor harms. I don't use it.AoB:
What common practices in bonsai can increase the possibility of ailments?Nina:
Other than when newcomers keep a juniper with glued-on rocks on top of the TV set, I don't get the idea that people are doing anything wrong. They live in areas that have certain insect pests or pathogens, and they aren't certain how to proceed. With the advent of the internet, they now have access to the webpages of all the major agricultural college's extension sites, so it's much easier to get informed. On the "Bonsai Doctor" site, I often only need to identify the pest and steer people to the extension websites.AoB:
What practices would you recommend to maintain a healthy and thriving bonsai?Nina:
Lots of water in a well-draining mix, and regular fertilization.AoB:
Naturalist claim that a few pests are better than no pest at all, due to the indiscriminative nature of pesticides, what are your thoughts on this subject?Nina:
My bonsai have very few insect pests I worry about. Pine tip moth and scales; that's about it. Natural enemies generally control the scales, and as I said, a familiarity with the life cycle of the pine tip moth allows me to avoid using chemicals. I'm a certified pesticide applicator, able to use all sorts of chemicals regular people can't, but I don't feel I need to use them.One of Nina's accentsAoB:
Reading through your publications, it is obvious that you also are involved with fungus. In bonsai, we often depend on beneficial fungus but fear harmful, wood eating fungus quite a bit. Is there a safe method to treat harmful fungus without also killing the beneficial?Nina:
I don't think I've ever sprayed my bonsai for a fungal disease. I remove and destroy diseased leaves; when I water a plant I avoid wetting the leaves. Most of all, I try not to stress the trees. They have natural defenses and beneficial partners and can largely take care of themselves if they are in good condition. Wood-eating fungi attack stressed trees.AoB:
What books would you recommend to those who wish to learn more or diagnose and treat bonsai pests and ailments?Nina:
People should visit their Cooperative Extension offices and pick up free (or cheap) literature, and bookmark the extension office's website. Extension agents know which pesticides are legal in their state, and know the timing of the pests and diseases in the region. That's crucial. I constantly refer to two books by my Cornell colleagues: "Diseases of trees and shrubs" by Sinclair, Lyon and Johnson, and "Insects that feed on trees and shrubs" by Johnson and Lyon, both published by Cornell University Press.AoB:
The import restrictions on plants from Japan are stifling, often entailing a couple years of quarantine, which many trees do not survive. Do you think these measures and precautions are necessary or overkill?Nina:
Sadly, they are necessary. An Asian Longhorn beetle grub can live inside a tree for two years before emerging. The regulatory agents should, however, try to understand the difference between a bonsai and a piece of lumber, and act accordingly.AoB:
Considering the very small amount of bonsai imported, as compared to lumber, wood mulch, and other such products, is the possibility of a invasive pest or disease really so threatening as to support the restrictions?Nina:
Yes. The disease I study, "sudden oak death", was probably brought to California on an infected Rhododendron. It probably wasn't a bonsai, but it could have been. The disease has now spread and killed tens of thousands of trees, damaged the California nursery industry, endangered birds and animals that feed on acorns, and increased the threat of wildfires. The Asian Longhorn beetle, which has been spread on bonsai, threatens the maple sugar industry in Massachusetts. The emerald ash borer is wiping out ash trees in the center of the country, and there's no way to stop it. Invasive species are a serious threat, not only to various industries in this country, but to the country's natural beauty.AoB:
At a recent bonsai show there were inchworms discovered on a Mulberry and sawflies on a pine. At a large exhibit I attended, there was needle cast discovered on a pine. In your opinion, should shows inspect entries better and if so, what method would you recommend?Nina:
My own club, the Baltimore Bonsai club, inspects its potential entries before bringing them to an exhibit. I have seen the club members reject a tree because they felt the show might be too much stress for it, or because it didn't look as healthy as it should. That's a good way to do it. AoB:
You currently have your own forum sub-section at IBC ( ibonsaiclub.forumotion.com ) in which you field questions about pests and disease; this is a valuable resource to the bonsai community, what led you to decide to donate your time doing this?Nina:
I almost cry every time I see a local grocery store selling "indoor" junipers next to the produce section. I often find the manager and explain how terrible this is for our hobby. A person who kills his first tree is going to be discouraged. If I can help people enjoy bonsai, I will.AoB:
What are the most common questions you receive there?Nina:
Before the website crash, I got a lot of beginner questions about indoor junipers; now with the new format, I get a lot of questions from experienced bonsai people and the questions are a lot more challenging. It's too soon for any common thread to be evident, and I hope people will check the list and see if a question has already been asked, and then not ask it again. AoB:
What are the most common ailments you identify there?Nina:
People don't realize it, but the common ailment is stress. It weakens trees and makes them more susceptible. AoB:
Your list of publications is quite impressive with vastly diverse subjects. Is there a place we could read all of your publications? When can we expect to see a list specific to bonsai?Nina:
Don't read those. They are technical and boring. I wrote a couple of articles for British Bonsai that I really enjoyed. Find the back issues.
Watering your bonsai. Bonsai (UK) 42: 45-47. 1999.
Fantastic voyage: the microscopic world of bonsai care. Bonsai (UK) 45: 37-39. 2000.AoB:
With your experience, there is little doubt that a book by you specially tailored to bonsai ailments would be very well received. When can we expect to see one?Nina:
I don't believe in books for recipes or plants. Go online, people. AoB:
Could you tell us a little about your own bonsai experience? Do you grow bonsai, if so how long, and who were your sources for inspiration?Nina:
I've been doing bonsai since 1987. My greatest inspiration has been Kyuzo Murata. He emphasizes that bonsai are a way to see nature. I might drive right by a red maple with bursting buds on my way to work and never notice it, but with my bonsai, I'm always aware of the season. When I see my amelanchier in bloom, I know the shadblow in the woods are blooming, too, and that the morels will soon be popping up.
My living inspiration is Brent Walston of Evergreen Gardenworks nursery. He knows a lot about plants.AoB:
Do your co-workers at the USDA know about your bonsai and do they express much interest or do they just think you are as strange as the rest of us?Nina:
I sometimes bring a tree in for our weekly meetings (if one of them is looking especially nice). Everyone is in awe of them (never having seen a really good bonsai), and I have to convince them that they could do just as well.