You Can Be a Plant Doctor

Being a plant doctor is actually similar to being a medical doctor – you get a sick patient, you check for symptoms, you make a diagnosis, and then you prescribe treatment.  The only problem though with being a plant doctor, is that your patients cannot tell you directly what is wrong.  In order to figure out what’s causing a plant to be sick, you need to be inquisitive, open-minded, and very knowledgeable. 

Photo: Correctly diagnosing plant problems takes a thorough, comprehensive approach. 

For simplicity’s sake, plant diagnosticians have broken down the causes of plant problems into two categories – biotic and abiotic agents.  Biotic agents are living organisms (other than people) that cause plant problems, including insects, mites, fungi, bacteria, viruses, mammals, birds, and nematodes.  On the other hand, abiotic agents are non-living things or phenomena that cause plant problems.  Examples include hurricanes, construction damage, damage from a weed-wacker, and saturated soil. 

Correctly diagnosing plant problems is essential to maintaining the health, beauty, and longevity of your landscape.  But correct plant diagnosis can be quite challenging.  First off, there are many, many things that cause plant problems.  You have thousands of insects, diseases, nematodes, environmental factors, and physiological problems that can wreck havoc on your plants.  Just knowing all the potential causes of plant problems is a challenge, let alone correctly identifying them!  Many different factors are often working together to cause a plant problem.  Usually an insect or disease is not working in isolation; it is influenced by the current climate and the past and current health of the plant. 

Photo: Except for exotic pests, insect and disease problems of plants are often secondary causes of plant decline, not primary causes.  This drought and heat-stressed birch tree was predisposed to insect attack by the native bronze birch borer.  Notice the insects' exit holes in the trunk.

Another difficult thing about plant diagnosis is that many causal factors will produce similar-looking symptoms in the plant.  For example, both a drought-stressed tree and a salt-damaged tree will show brown crinkled leaves and leaf drop.  Furthermore, landscapes are variable and diverse.  Hundreds of species are planted in the landscape and each landscape has a different combination of plants.  Also, the planting sites themselves are highly variable, with differing soil, terrain, light exposure, and microclimate. 

Because of the difficulty of diagnosing plant problems, a thorough, comprehensive, step-by-step approach is needed.  Step 1 – Identify the plant.  Central to correct diagnosis is accurately identifying the species and sometimes the cultivar.  This is because you need to know what the cultural requirements, normal appearance, and growth characteristics are of a plant before you can detect that there is a problem.  For example, if a plant is yellow and drooping, you may conclude that it has a nutrient deficiency or is drought-stressed.  But if a Gold Thread Cypress (Chamaecyparis pisifera ‘Filifera Aurea’) is yellow and drooping, there is no problem and it doesn’t need more nitrogen or water. 

Step 2 – Inspect the site.  Look for conditions in the landscape that may lead to plant injury.  There are many questions to ask, including:  What is the slope of the terrain?  What is the soil texture – sandy, loam, clay?  What are the soil pH and nutrient levels?  Is it a well-drained soil?  Is it a compacted soil?  Are there dry or wet areas?  Is it a windy or protected site?  Is it shaded or in full sun?  Is there existing hardscape?  Is there existing vegetation nearby?  Are there animals or pets that access the site?  Is there mulch or grass beneath the plantings?

Photo: Figuring out what type of conditions at the site may lead to plant problems is essential for proper diagnosis.  Poor drainage is a common problem in urban landscapes that have compacted soils. 

Step 3 – Investigate the plant management and site history.  Gather as much information as possible and check your maintenance records if they exist.   Any information may provide you with clues to the problem.  There are many questions to ask here as well, including: When was the problematic plant planted?  What was the season of planting?  How large was it when planted? What type of nursery stock was used?  Were there any previous problems?  What are the current irrigation, fertilization, pest management, and pruning, practices?  Were any herbicides used?  Are there underground utilities?  Was there any recent construction(less than five years ago)?  Were there any recent abnormal weather conditions (less than two years ago)?  Were any deicing salts used?  

Step 4 – Inspect and describe the plant symptoms.  In most cases, you will only see the symptoms of a plant problem.  A symptom is the plant’s response to a disorder resulting in abnormal changes in the growth or appearance of a plant, which may be observed on the leaves, shoots, branches, flowers, trunk, or roots.  The difficulty of plant diagnosis is that symptoms are usually non-specific, meaning that several different disorders can result in the same symptom.  You need to gather more information and make close observations.  Ask, which plant part (roots, flowers, shoots, etc.) is affected and how severely?  Is there leaf chlorosis (yellowing)?  Is there leaf necrosis (browning and death)?  Is there discoloration or distortion?  Is the plant a normal size?  Is the plant wilting?  Are there a lot of dead branches and dieback?  Are there tattered leaves?  Any defoliation?  Is there early fall color?  Is the bark falling off?  Is there any bleeding or localized swelling?  Is there trunk splitting or cracking?  How do the roots look? 

Step 5 – Look for patterns and signs.  The pattern of symptoms throughout the plant and the landscape can sometimes give you a hint as to the problem.  If symptoms are uniformly distributed throughout the plant, it can mean that there is an underlying issue with the root system.  If only one plant is affected it can mean that there is an abiotic problem at that specific micro-site.  If only one species is affected, it can mean that there is a species-specific insect or disease problem.  Also look for signs.  When you actually SEE the presence or activity of an insect or disease, this is called, in very scientific terms, a “sign.”  A sign is direct evidence of an insect or disease.  Examples of signs are: adult insects, eggs, nymphs, larvae, pupae, cocoons, shed insect skins, frass, protective wax, exit holes, and fruiting bodies of a fungus.  These can be collected and sent to a lab for diagnosis.

Step 6 – Inspect the rest of the plant for abnormalities.  It is so easy for us to just think about the above-ground portions of trees and shrubs because that is what is visible to us.  But we really need to examine the roots and soil to get at the underlying cause of many landscape problems.

And lastly, Step 7 – Test likely causes and make a diagnosis.  Take soil, water, and tissue samples if needed and get them tested.  Make sure that your diagnosis is consistent with standard descriptions of the problem.

Diagnosing and correcting plant problems is challenging.  But with a comprehensive approach and practice, you’ll be able to figure out what’s wrong with a sick plant.

One in a Million

It’s been said that a picture is worth a thousand words.  But for Washington DC, a picture was worth $50 million.  In 1999, satellite pictures in the Washington Post clearly displayed a dramatic loss of tree cover in the District of Columbia, showing far more pavement than trees.  The accompanying article explained that the number of acres of heavy tree cover had dropped by 64 percent over the past two decades, as trees died due to disease, development, and old age, and were not replaced.  The shocking pictures motivated philanthropist and long time resident, Mrs. Betty Brown Casey to generously donate $50 million to re-green the city.  Her donation established the non-profit Casey Trees, which is officially charged with restoring, enhancing, and protecting the tree canopy of our nation’s capital. 

Photo: Trees, gardens, and parks make our densely populated cities liveable, like this tree-lined street of Park Slope, Brooklyn.

During the summer of 2002, I helped Casey Trees with the initial tree inventory and planning process.  Using a hand-held GIS, I traipsed around Washington DC with volunteers measuring and assessing the health of individual street trees.  As we walked the innumerable city blocks, I entered on my digital map the tree information and where new planting opportunities were.  After three months, our dedicated team finished inventorying over 100,000 street trees.  The soles of our sneakers had grown thin, our calves had grown wide, and our bright yellow safety vests had become tattered and stained.  Nevertheless, we were proud of our accomplishment and excited that DC would soon become greener with our help. 

For nearly the past decade, Casey Trees has worked alongside the DC government planting and maintaining the urban forest.  Over 10,000 trees have been planted and thousands of people have been educated on the important role that trees play in making our communities livable.  Casey Trees continues to work diligently towards its goal of creating 40% tree cover in Washington DC by 2035.  (For more information, visit www.caseytrees.org)

Photo:  Tree-lined street of Washington DC

Urban reforestation programs are taking the country by storm.  Not to be outdone, in 2007 Mayor Bloomberg announced a new initiative to create “a greener, greater New York.”  As part of his new plan for NYC, an ambitious goal was created to plant one million new trees across Manhattan, Brooklyn, Queens, the Bronx, and Staten Island by 2017.  Led by the NYC Department of Parks and Recreation and the non-profit New York Restoration Project, MillionTreesNYC has already planted nearly half a million trees.  70% of trees will or have been planted on public land in existing parks and forests and along streets.  The remaining trees will or have been planted on private land on individual properties or institutions.

Photo: Planetree (Platanus x acerifolia) is the most common street tree in NYC, comprising 15% of the trees

Although MillionTreesNYC is a citywide initiative, half a dozen neighborhoods have been identified as focus planting areas.  The neighborhoods of East Harlem, Manhattan; East New York, Brooklyn; the Rockaways, Queens; Stapleton, Staten Island; Hunts Point, Bronx; and Morrisania, Bronx are at a critical need for trees, with higher than average rates of childhood asthma and lower than average number of street trees.  Planting trees, especially in these areas, will hopefully reduce the pollutants that trigger respiratory disorders and help create a healthier living environment for all.

If you live in any of the five boroughs, you can request a free street tree (if you don’t have a tree already) at:  www.milliontreesnyc.org/html/involved/request_a_tree.shtml  If you don’t feel like waiting, you could instead plant a street tree on your own by first obtaining a tree planting permit.  Be aware that there are tree height and species restrictions.  Learn how to care for your new street tree at one of the many free workshops offered by the MillionTrees Stewardship Corps. 

Photo: A greener city - park in Chelsea, Manhattan

It is truly remarkable that urban trees in NYC, Washington DC, and other cities have such a positive impact on the environment and people’s well-being.  Even more remarkable is that politicians are recognizing the importance of trees!  Through the efforts of MillionTreesNYC and the other sustainable initiatives of PlaNYC, New York City - the greatest city in the world - will soon become the Big “Green” Apple! 

Annually, it is estimated that NYC’s 592,000 street trees provide:

·         $52 million in increased property values;

·         $36 million in stormwater runoff abatement;

·         $27 million in energy savings;

·         $5.3 million in improved air quality; and

·         $0.75 million in carbon dioxide reduction.

(STRATUM results based on 2005-06 NYC Street Tree Census)

For more information, visit MillionTreesNYC at: www.milliontreesnyc.org  

Oh Deer!

You don’t need to travel upstate New York to see a deer.  If you live on the eastern two-thirds of Long Island, you may only need to look out your window at dusk to see a doe or buck grazing in the twilight.  White-tailed deer (Odocoileus virginianus) is a species of wildlife native to the East Coast and Long Island that has been reported as far west as Eastern Queens in recent years.  In conversations with friends, landscapers, and nursery growers, I find that everyone I talk to has a very strong opinion about deer - opinions which span quite the gamut.  For example, one homeowner on Fire Island that I know keeps a daily log of all the deer that walk in and out of her beach property.  Not only has she named every deer, but she also knows who is related to who and the genealogy of the entire herd.   On the other side of the gamut, at our July 4^th BBQ, we ate venison that was proudly provided by my co-worker from one of his hunting trips.  As we ate, another co-worker recounted when a deer had accidently become trapped inside our fenced research fields, and he had to chase it out with the golf cart, but not before it had trammeled through the property wrecking havoc on our neatly planted experiments. 

These deer stories have helped me realize that there seems to be three distinct ways of thinking about deer – as innocent and beautiful animals to be protected, as nuisance pests that are highly destructive, or as potential trophies and sources of healthy, wild game.  But all too often, these three different viewpoints do not overlap and one opinion is vehemently defended, while the other two are condemned.

Photo: According to the U.S. Department of the Interior (2008), nearly 1.2 million New Yorkers enjoy viewing deer near their home.  Watch Hill, Fire Island

Perhaps we would have room for these different opinions if it wasn’t for the sheer number of deer.  Although white-tailed deer are a natural part of Long Island’s ecosystem, numbers have greatly increased over the last century throughout the East Coast.  New York’s deer population spiked to over 1 million between 2000 and 2002 (DEC 2011).  Removal of natural predators, conversion of dense forest to habitat preferred by deer, and a nearly 40% reduction in deer hunting participation in New York since the mid-1980s are the cause of extraordinarily high numbers of deer in the state.  

This exploding population of deer has created a melee of problems which threaten all three different perspectives on deer.  There are now too many deer to protect all these beautiful animals from winter starvation.  There are now too many deer to economically protect highly valuable crops upon which people depend for their livelihood.  There are now too many deer to protect seedlings in the forest understory from not being eaten and growing into mature trees, forever altering the composition of our remaining forests.  There are so many deer that they are now one of the number one sources of wildlife-related car collisions.  There are so many deer that the risk of Lyme disease is incredibly high.  There are so many deer that hunters are now sometimes given incentives to shoot a female doe rather than a prized male buck (This apparently lowers the population more efficiently.)  In essence, everyone’s opinions about deer are at risk, which makes people cling even more tenaciously to those opinions and beliefs about nature at large.  What began as a simple argument about deer, has snowballed into an embittered battle of beliefs, values, and our relationship with nature.    

Although beautiful animals, there is no way that deer can be considered innocent little Bambis, as they are the source of many very serious environmental, economic, and public health problems.  The Wildlife Bureau of the NYS Department of Environmental Conservation continues to seriously address these deer-related concerns.  In June 2011, they published a Management Plan for White-tailed Deer in New York State, 2011-2015.  In this document, the DEC confesses that, “Balancing the deer population with the often conflicting demands of the various stakeholders impacted by deer has been and continues to be a fundamental challenge for deer managers.” (Read the whole report at: http://www.dec.ny.gov/docs/wildlife_pdf/draftdeerplan0611.pdf)

Whatever your opinion is about deer, you can minimize damage to your landscape by installing plants that deer prefer not to eat.  There are no truly deer “resistant” plants, since if deer are hungry enough they will eat just about everything.   That being said, you can pretty surely bet that deer will avoid eating Boxwood (Buxus spp.), Japanese Andromeda (Pieris japonica), Russian Sage (Perovskia atriplicifolia), and Catmint (Nepeta x faassenii).  Avoid planting deer favorites, which include Yew (Taxus spp.), Hosta (Hosta spp.), Rhododendron and Azalea (Rhododendron spp.), and Eastern Arborvitae (Thuja occidentalis).  Your other option is to surround your property with an 8-10 ft. tall deer fence.

Photo: 'Walkers Low' Catmint (Nepeta x faassenii), a good plant for deer-prone gardens. 

Photo: 'Brouwer's Beauty' Andromeda (Pieris japonica), a good plant for deer-prone areas.

 

Until wolves are reintroduced onto Long Island or the number of hunters increases dramatically (neither of which seem very likely), we’ll continue to have to find ways of graciously accepting deer as our permanent backyard neighbors.