“Clouds are not spheres, mountains are not cones, coastlines are not circles, and bark is not smooth, nor does lightning travel in a straight line.”

– Benoit Mandelbrot, introduction to The Fractal Geometry of Nature

At this time of year many of the trees and shrubs in our landscapes are mere skeletons of their summer glory. Their beautiful canopies of leaves have been shed and they provide little visual interest. Unless you look a bit closer…

maple-tree

This is actually a great time to observe the branching patterns of deciduous trees. A closer look reveals that they are eerily similar to our own vascular and respiratory systems. As each system goes from the main trunk to the larger limbs to the smaller branches and then the twigs we see the same fractal branching that occurs in the network of blood vessels in our lungs. How incredible that such like systems are actually performing a reverse process. Trees are taking in our exhaled carbon dioxide and releasing oxygen (O2) into the atmosphere.  In turn, we inhale that O2 rich air into our lungs where it travels through the increasingly smaller vessels until it reaches the capillaries where it passes through into our bloodstream. As the oxygen-rich blood travels through our body our cells use the oxygen and release CO2 back into the bloodstream where it travels back to our lungs before releasing CO2 as we exhale.

2012-11-23_07-39-50_640

The important thing to remember is that for both of these systems to work well they need to cover a large surface area and fractal branching is the most efficient way for that happen. Fractal branching is a pattern that repeats itself in either larger or smaller scales, each step looking like a copy of the same overall shape. These patterns are called self-similar and are found in many areas in nature from trees to rivers and many more. Ferns are a great example of a self-similar fractal as each pinnate leaf is a miniature version of the larger frond that it branches off from although natural branching fractals do not go on infinitely as mathematical fractals can. Remember the Fibonacci Sequence from your high school math class?

japanese-painted-fern

Most of the fractals that we are familiar with and see on a regular basis fall into the category known as spiral fractals. Spiral fractals are responsible for some of the most beautiful forms that can be found in nature. Many galaxies are spiral fractals. The marine animal known as the Nautilus is perhaps one of the most well-known examples of the spiral fractal. But there are also so many spiral fractals that we encounter in the plant kingdom on a daily basis.

Ferns exhibit fractal properties in two ways. The uncurling of a new fiddlehead in the spring is a lovely example of a spiral fractal while a mature Japanese Painted fern (Athyrium niponicumn) pictured above shows the self-similar pattern of a branching fractal.

The Monkey Puzzle tree (Araucaria araucana)  has a most interesting growth pattern with each branch a continuing spiral of tough, scale-like leaves. Although native to Chile and Argentina, these images are of a specimen that is located on the Long Island campus of Hofstra University.

Closer to home are some plants that are in many of our gardens during the summer season. The compact spirals of Stonecrop, also known as Sedum, help to form the tight clusters of thick leaves that give it its distinguishing look. I always love the way that dew or rain collect in the in little cups that are formed.

Sunflowers (Helianthus annuus), Gerbera (Gerbera) daisies, and Coneflowers (Echinacea purpurea) show their spirals on a grand scale.

Decorative cabbage and kale (Brassica oleracea) are seasonal plants that bring their cold-resistant beauty to our fall landscaping and thus complete a full year of natural fractals that can be found all around us .

ornamental-cabbage-2

Susan Pelton

Spittlebugs are common and easily recognized by the white foamy ‘spittle’ produced by the nymph or immature stage of the insects as they feed. Adults are less often seen but are commonly known as froghoppers (close relatives of leafhoppers, etc).  Depending on the reference, there are anywhere from 30 to 60+ spittlebug species in the United States.  All feed on plants, including both woody and herbaceous types.  Some spittlebugs have broad host ranges and others narrow.

spittlebugfoam-bugwood

‘Spittle’ produced by nymphs on a plant. Photo by: G. Lenard, LA State Univ.

 

There is usually only one generation per year and most overwinter in the egg stage inside overwintering plant tissue where they were deposited by the females in from mid to late summer to early fall, depending on species. Hatch occurs in the spring, probably in May in Connecticut.  Even though spittlebugs feed by extracting plant sap/juice through needle-like mouth parts, they seldom cause notable injury to the plant.  There are a few exceptions including the meadow spittlebug (Philaenus spumarius) and the pine spittlebug (Aphrophora cribata).

Color variations of the meadow spittlebug adult.  Photos: Cheryl Moorehead,     bugwood.org

The meadow spittlebug has a broad host range that includes both herbaceous and woody plants. It is reported to cause damage in clover, strawberry, mint, herbaceous ornamentals and both coniferous and broad-leaved woody plants when present in high numbers.  Other common names include the common froghopper and the cuckoo spit (most common name in the UK).  Eggs are laid in the stems or crevices of host plants in the fall.  When they hatch in the spring, nymphs usually feed on the plant the eggs were laid on but they will move to younger more tender tissues as the plant grows.  There are five nymph stages and all produce spittle as they feed.   Once the adult stage is reached, spittle is no longer produced and the adult is quite mobile, quickly jumping a long distance relative to its size when disturbed.

The froghoppers or adult stage are so-called because their bodies are somewhat wider at the rear like a frog. The name cuckoo spit may have come about because the spittle tends to be first seen in the spring around the same time that the first calls of the cuckoo bird are heard.  Most adults are brown to green in color with only subtle markings but some species have striking coloration or patterns.  The meadow spittlebug adult is quite variable in coloration.

So, about the spittle. The spittle offers some clear benefits to the nymph(s) hiding within.  First, it helps prevent the soft-bodied little guys from drying out.  In addition, it protects them from detection by potential parasites and predators.  A single mass of spittle may be inhabited by multiple nymphs feeding in the same area on the plant.  How is the spittle produced?  First, the spittlebug ingests more plant sap than it needs for its nutrition/sustenance.  The excess is expelled through the anus as a watery waste product.  It mixes with a mucilaginous fluid produced by glands on the abdomen and air bubbles are introduced from a special canal by abdominal contractions.  This is pretty interesting stuff going on in gardens, forests and meadows all around us each spring and early summer!

spittlebugnymph-bugwood Spittlebug nymph.  Photo: David Cappaert, Bugwood.org

If you would like to get a closer look at a nymph, don’t be afraid to brush the foam carefully away from a plant and look for them inside. They will be up to ¼” long depending on their stage of development and may be yellowish, greenish or brown in color.  They are elongated and generally are positioned head down. This facilitates the movement of the spittle downward to cover them.  Nymphs are shy and will not be happy to be exposed.  They will attempt to walk away but cannot run or fly.

The biggest problem with spittlebugs in the garden, whether it’s an ornamental or food garden, is the unsightliness of the spittle masses. Spittle and nymphs can both be washed off the plants with a steady stream of water.  On a small scale, they can be hand-removed and disposed of.  Normally, no chemical controls are recommended and the spittle protects nymphs from contact insecticides.  Not sure if there are enough spittlebugs to cause plants to be weakened?  Look for distorted or stunted new growth, and of course numerous spittle masses on the same plant.

In a few cases, additional injury to the host plant can occur if toxic substances are introduced into the plant while feeding or if the froghopper/spittlebug is vectoring a plant pathogen (could be a virus or phytoplasma).  Feeding wounds can create entry points for some pathogens.

By J. Allen

January always finds me a bit restless. The holidays are over and it is time to dedecorate the house, the weather may or may not support outdoor activities like walks or cross-country skiing, and that New Year’s resolution of cleaning up the attic seems more daunting with every passing week. So to find some peace of mind, I reach for a hot cup of herbal tea and my stack of seed and plant catalogs that has been climbing higher each day the mail comes.

Like many gardeners, I start off with a wish list. Fanciful, curious, gorgeous or productive new, or previously unknown to me, selections are listed in my seed notebook to be later pared down to what I actually have room in the garden for. The eyes are always bigger than the garden!

I thought I would share some selections in the first few catalogs that I have received which caught my eye. Several new selections from the Park Seed catalog (www.parkseed.com) got my attention. Since I am always looking for cut flower selections, cosmos ‘Cupcakes Mixed’ looked interesting with its fused petals resembling a cup, hence the name. It is supposed to grow 4 feet tall and stand up to heat, rain and drought.

Multi-colored marigolds may work well as bedding plants. ‘Strawberry Blonde’ has double pompom blossoms with petals of coral, peach, gold and orange. I am seriously considering it for lining the front walkway this year. ‘Fireball’ also offers big double flowers that are open red and then turn orange, bronze or gold. Both are compact plants reaching about 10 inches high.

marigold-straw-blonde-park-seed

Strawberry Blonde Marigold from http://www.parkseed.com

Parks also offers a blueberry that fruits twice in one year. ‘Bushel and Berry™ Blueberry Perpetua’ not only fruits in midsummer and again in fall but the leaves change to red in the fall and the yellow stems turn red in the winter making this 4 to 5 foot high plant productive and attractive year round.

Pinetree Garden Seeds (www.superseeds.com) is offering two new kales. ‘Siberfrill’ is quite decorative with its frilly edged leaves while ‘Dazzling Blue’ is just that with bluish-tinged leaves and pinkish-purple midribs. Enjoy them for their decorative as well as eating qualities. ‘Edox’ lettuce is a disease-resistant, butterhead type with attractive burgundy edged leaves that reputedly grows well spring through fall.

Two snap peas will also likely end up in my garden. ‘Sugar Magnolia’ has pretty pink bicolored flowers that turn into deep purple edible podded peas and plants are said to beat the mid-July heat. ‘Opal Creek’ sports white flowers and pastel lemon pods on 6 foot vines and also holds up well to summer heat. ‘Corbaci’ is a sweet pepper with super long, thin fruits that bears heavy and early. This Turkish heirloom can be eaten at any stage and can be used fresh, dried, for pickling or frying.

sugarmagnoliapea-from-pinetree

Sugar Magnolia Pea from Pinetree Seeds http://www.superseeds.com

It is hard to choose tomatoes or peppers from Totally Tomatoes (www.totallytomatoes.com) as there are just too many choices. Usually I just grow sweet peppers but may try ‘Sriracha’ this year. The chili-type fruits are supposed to be mildly hot but not overpowering. The thick-walled, early maturing fruits are good for roasting and pickling. Another interesting pepper is ‘Jupiter’ which is an open-pollinated reintroduction. Blocky fruits ripen to red on 30 inch, tobacco mosaic resistant plants.

‘Sunrise Sauce’ is a hybrid, determinant tomato that is resistant to fusarium and verticillium. Three to 4 ounce orange fruits taste like the traditional red Romas. High yielding fruits ripen all at once which is convenient for sauce making. ‘Tasmanian Chocolate’ is in a unique dwarf class of tomatoes. Three foot tall plants produce large 8 to 12 ounce mahogany red, beefsteak tomatoes delicious fresh or cooked.

tasmanianchocolate-heritageseedmarket-com

Tasmanian Chocolate tomato. Photo from http://www.heritageseedmarket.com

Johnny’s Selected Seeds (www.johnnyseeds.com) is offering All America Selections Regional Winner, eggplant ‘Patio Baby’. This compact mini eggplant would work well in small gardens and containers. Purple flowers are followed by purple, 2 to 3 inch, spineless fruits.

‘Xtra-Tender’ is an early bicolor sweet corn and the first supersweet variety available as organic seed. Supposedly it germinates well in cool soils, is of excellent eating quality and matures in 71 days.

New to me are some mini romaine lettuces. Too often too many lettuces mature all at once and there is just so much salad a person can eat. ‘Dragoon’ is a green, mini romaine that is slow to bolt. ‘Breen’ is a medium bronze mini only 8 inches tall and ‘Trunchas’ is a dark red. All mature in less than 50 days and show some disease resistance.

Sunflower ‘Florenza’ has dark centers ringed with a deep burgundy and tipped with gold. Plants grow about 4 ½ feet tall and flowers have a mild chocolate fragrance.

florenza-johnnys

Sunflower Florenza from http://www.johnnyseed.com

The last couple of years I lost my basil plants to a disease known as basil downy mildew. New from Burpee (www.burpee.com) is ‘Pesto Party’, a late-flowering basil with tolerance to downy mildew. Coleus ‘Pineapple Surprise’ sounds like a container hit with its chartreuse and burgundy leaves swirled with chocolate brown.

basil-pesto-party-from-burpee

Basil Pesto Party from http://www.burpee.com

A definite addition to the cutting garden is celosia ‘Red Velvet Cake’. Three to 4 foot plants have strong stems that do not require staking. The vibrant crimson heads look like they will make great fresh and dried flowers.

celosia-rvc-burpee

Celosia Red Velvet Cake from http://www.burpee.com

Territorial Seed Company (www.territorialseed.com) has a uniquely colored butternut squash, ‘Autumn Choice’. Classic butternut-shaped fruit have attractive orange and green speckled bands. Not only is butternut a great tasting squash but because of its solid stems, members of this species, Cucurbita moschata, are not attacked by squash vine borers.

autumn-choice-squash-territorial

Autumn Choice Winter Squash from http://www.territorialseed.com

Another fun squash is offered by Henry Fields (www.henryfields.com). ‘Dinosaur Eggs’ is a hybrid summer squash with round fruit in three colors – pale green, dark green and yellow. It is listed as disease resistant and productive.

These are just some offerings that piqued my interest and I have yet a dozen or more catalogs to go through. It is fun to try new vegetables and flowers while growing some old favorites. The hard part is whittling down the list to ones you can afford – both space and time wise.

Happy Horticultural New Year!

Dawn

 

lime-bag-homedepot

Bag of Lime

Many Connecticut residents spread limestone on their garden beds and lawn as an annual ritual. Why do we do this? Some do it because their parents did it, or the guy at the garden center told them to and sold them the limestone. How much should be purchased and applied is another mystery to most. The real answers of limestone’s why, how much and when lies in the science of soil.

Soil is made up of sand, silt, and clay. The percentage of each of these three determine the soil’s texture, which will determine how the water will move through it, or hold on to moisture. More clay equals wetter soils; more sand, better drainage. The sand, silt and clay are tiny pieces of rock, broken off of bigger pieces over much time by weathering. The rocks that makes up much of Connecticut has a naturally low pH in the 4.5 to 5.5 range. Other areas of the country and world have different rocks with different pH ranges. Acid rain falling onto the ground lowers pH levels, as does the action of organic matter decomposing which produces organic acids. Even the normal function of respiration by plants mixing oxygen and water together produces carbonic acid in the soil. More acid equals lower pH. No wonder why we need to test, monitor and fight the natural tendency of our soil to stay in a low pH range.

Most plants we want to grow require a pH range of 6 to 7. This means we have to change the pH to grow plants like grass, tomatoes, peppers, squash or garlic by adding limestone which raises the pH level. The only plants consistently happy with our native range are native plants! They have evolved in the local soil. This is why blueberries, oak trees and mountain laurel fill our forests and wild areas. Pines are another tree preferring our lower pH.

Why do the grass and vegetables prefer the 6 to 7 pH range? Because more of the nutrients that these species of plants need are available when the soil pH is in that range. The easiest way to think of pH is it is a measurement of the amount of hydrogen ions in the soil. The more hydrogen ions, the more acidic the soil is. The pH of the soil affects the availability of all plant nutrients. Just as plants have ideal moisture and light requirements, they have a preferred pH range as well.

The pH range numbers 0 to 14. The middle is neutral at 7. Pure water has a pH of 7. 0 is acid or bitter; 14 is alkaline or sweet. Old time farmers used to taste the soil to determine if it was bitter (acid, low) or sweet (high, alkaline). I am glad we have pH meters and laboratory soil testing equipment now!

0_________________________________________7_____________________________________14 Acid (Bitter)                                                                           Neutral                                                                  Alkaline (Sweet)

Soil pH levels also affect other life in the soil such as insects, worms, fungi and bacteria. The soil is alive with more than just plants. It is an entire ecosystem sustaining many life forms all interacting with each other. The pH level is probably the most important place to start when trying to provide the best environment for whatever plants you are growing.

Have your soil tested for pH and nutrient levels at the UConn Soil Nutrient Laboratory www.soiltest.uconn.edu. Have the $12.00 basic test for Home Grounds and Landscapers done. Forms and directions are on the website. We will be offering free pH only tests at the CT Flower Show February 23-26, 2017. A half cup of soil is needed. If you don’t have snow covering your ground now, go gather some soil now and hold it until the show. Once you know the pH of your soil, we can tell you how much limestone to apply in the spring. Fall is the best time to put down lime as it needs about six months to fully react and change the soil pH. Never put limestone down on frozen or snow-covered soil to avoid it running off to areas you didn’t intend to lime, like the storm drain. Limestone will not soak into frozen soil.

ph-meter

pH Meter

-Carol Quish

waxwings-between-bites-of-hawthorn-fruit-pamm-cooper-photo-12-19-16

Cedar waxwings in a Hawthorn tree, an important food source for birds in the winter

I love the outdoors and have spent a lot of time off the beaten track exploring since I was a young adult growing up in the Chenango River valley in New York. The way to get acquainted with nature is to get out in it. And I have done so all my life. This year was a good one for me personally as far as observing nature in all its glory. Even though the weather was colder in the spring and hotter and drier in the summer, and perhaps was the hottest year on record, there was a lot going on, both on a typical and uncommon level.

The first surprise was a pleasant one- a larger than average number of foxes spotted in all kinds of places. Innumerable times I saw foxes in the wee hours of morning returning with prey for their young. Whether in rural or residential areas, these animals were having a great year. The ones I saw had healthy skin and fur, and certainly had no trouble finding food. On the golf course where I work, there was a pair of foxes that had a den of kits just inside the woods by a tee. Every day like clockwork, they had a specific route they traveled going from the den to hunt, and they had a specific, different, route returning to the den with their quarry. The good news was they killed a lot of troublesome landscape troublers- mice, voles and even several woodchucks.  Later on, the parents would be accompanied by the kits as they learned to hunt.

coopers-hawk-2016-november

Cooper’s hawk patrolling near a bird feeder

Although a dry year, the two or three thunderstorms we had brought out a few creatures the next day. One of my favorites is the eft form of the red- spotted newt. These tiny, bright orange amphibians sometimes  venture out of the woods after a rainy night and sometimes can’t seem to find their way back. Several fairways tend to have these guys on them in the mornings, so I am on the alert for them as I mow. Box turtles are also known to put in a similar appearance on days after summer rains. This year I was able to help a granddaddy of a box turtle get across a very busy road safely. This particular turtle  was one of the most ornately marked ones I have ever seen.

eft

Eft form of the red- spotted newt happily returns to the woods

Another creature that had an exceptional year was the Spicebush Swallowtail butterfly. The previous year, they were few and far between, but in 2016 they had a banner year. The host plants of the caterpillars are spicebush and sassafras and careful examination inside leaves  folded lengthwise reveal the larvae of this butterfly. It seemed like whenever you came across  a host plant, at least one of these caterpillars was somewhere on it. On one small spicebush in a butterfly garden there were six caterpillars from eggs laid by six different females.

spicebush-swallowtail-cats-late-season

Two spicebush swallowtail caterpillars found on the same sassafras sapling

Fall leaf color wasn’t great at first- perhaps because of the drought- and some red maples that turned early were actually yellow or brown in color. But there was a snap of cold in early October and a day later the leaves were at peak color, a sudden surprise after a drab start. Oaks were also beautiful this year- not dominated by the browns of last year. Red and white oaks had striking reds, and some red oaks produced yellow or tan. Acorns were not particularly abundant, but enough were around to keep deer, turkeys, squirrels and chipmunks in good supply. This was actually good for the squirrels and chipmunks because in late September and early October they were not able to find many maple seeds to eat because of the sudden freeze in April that caused many maple flowers to drop early.

willow-leafing-out-in-snow-4-3-16

Willow leafing out in the snow on April 3, 2016

While insect populations, especially caterpillars, seemed low this year, bumblebees and other native bees abounded. Late season bloomers like mums, asters and goldenrods provided many insects with a good source of pollen and nectar. I found a small goldenrod in full bloom after Thanksgiving, which was very unusual. Bumblebees, some small native bees and honeybees were active up until Thanksgiving week, at least here on the UConn campus and in my backyard garden because alyssum, some hydrangeas and a few obedient plants were still in flower. And the caterpillars of the imported cabbage worm butterfly abounded late this season- even into December- especially on certain ornamental cabbages. A good find this year was a scarlet malachite beetle- on a blade of grass near my front step. This was only the second one I have ever seen, so it was a noteworthy event. The excitement never ends…

scarlet-malachite-beetle-front-yard-5-14-16-pamm-cooper-copyright-2016

scarlet malachite beetle

This year there was a pair of barred owls that had a nest inside a standing dead tree trunk on the side of a country road I travel on every day. In the pre-dawn when I passed by on my way to work, the parent owls would often be bringing the last protein nuggets of the night’s hunts back to their young. In the afternoon, both parents would be guarding the nest from perches nearby. In the pre-dusk twilight, the young owls would appear at the entrance of the nest hole and let it be known that they were hungry. And so the hunts would begin, to continue until the following dawn. I missed them all when they fledged and went off into the wild blue to learn to be on their own.

barred-owl-across-from-nest-at-dusk-5-16-16

Barred owl guarding her nest during the day

Wild blueberries were especially abundant this year, as were huckleberries. Noticeably fewer were dewberries, which are produced by plants that creep along the ground. Late in the season, migrating birds had few cedar berries to eat (unlike the bumper crop of last year), but at least black gum, poison ivy and Virginia creeper were loaded with fruit. Migrating warblers such as the yellow- rumped warblers are especially fond of these fruits. And if you have a bird feeder and some woods nearby, keep on the lookout for small raptors like the Cooper’s or the sharp-shinned hawks which prey on other birds. If birds around the feeder scatter suddenly, there may be a good reason, apart from a cat. During the winter, check out any hawthorn or crabapple trees that still have fruit. Robins and cedar waxwings are common winter visitors to these trees.

And as a final note, enjoy what is left of the year. And have a Merry Christmas! Or whatever you may celebrate at this time of year…

highland-park-springs-christmas-2016

Highland Park Springs Manchester, Ct.

 

 

 

 

 

If you could pick a superpower what would you choose? Extraordinary strength? Extrasensory perception? Exceptional intelligence? How about the ability to predict the future?  Or at least the weather? It would be so much easier to plan and plant a garden each year if we only knew what the growing season had in store. Is it going to be a very long, cold, and wet spring with a frost at the end of May? Then the warm weather crops shouldn’t go into the ground until the start of June when the soil will be warm and dry enough to encourage germination of seeds such as beans which do not like cold, wet feet. Will a lack of precipitation stunt plant growth and require more supplemental watering than usual?

It’s no surprise to anyone at this point that Connecticut is experiencing drought conditions that range from abnormally dry to extreme drought conditions in the western part of the state according to the USDA. The National Weather Service Seasonal Drought Outlook only extends through February 28, 2017 at this point but it predicts that the drought will persist in the Northeast based on “subjectively derived probabilities guided by short- and long-range statistical and dynamic forecasts”. Say that three times fast!

weather-chart

The National Weather Service, which is a division of the National Oceanic and Atmospheric Administration, was formed in 1970 under President Richard E. Nixon’s administration. Prior to that date they were known as the Weather Bureau (forms 1870) and before that, the United States Coast and Geodetic Survey (formed 1807). It’s safe to say that NOAA has the most up to date weather technology including geosynchronous satellites, Doppler weather radar, and undersea research centers. But even with that technology most predictions are only up to 90% accurate for 6-10 days out. Past that it becomes probable trends based on current and past information.

And yet, for 225 years, there has been a resource that claims that its weather forecasts are 80-85% accurate. Since 1792 the Old Farmer’s Almanac has been a go-to resource for weather, astronomy, gardening, cooking, and predictions of trends in food, fashion, and technology.

About that weather accuracy claim: the Old Farmer’s Almanac has a closer to 50% predictability rate. But that doesn’t stop thousands of readers, especially in the pre-National Weather Service days, from using it as their planting and growing guide. Its folksy character is a large part of its charm. Not to mention its compact size and unique punched hole in the upper left-hand corner for hanging from a nail or string in the outhouse. I pause for a second to express gratitude for modern indoor plumbing.

And now, spoiler alert, here are the Northeast predictions for 2017 from The Old Farmer’s Almanac: Although there will be lower precipitation than normal in January it will be at or above normal for February through July with temperatures 1-4° below normal for most of that period. Pretty much the opposite of what 2016 brought us. But what stands out the most is the blizzard accompanied by bitter cold that is predicted for February 11-17. Let’s hope that one isn’t correct!

Susan Pelton

Images NOAA, Old Farmer’s Almanac

 

Oak wilt is an important disease to be on the lookout for in New England. This is especially true for Connecticut because it has been confirmed in three locations in our neighbor to the west and south, New York.  The disease is important because it kills trees in the most susceptible red oak group (northern red, black and pin oaks in our area) within weeks or months of infection.  White oaks are more moderately susceptible and are generally not killed for a few to several years.  Early detection of this disease in any new location is critical to attempting to eradicate the problem before it becomes widespread.  The causal fungus is Ceratocystis fagacearum.

Oak wilt was first confirmed in the U.S. in Wisconsin in 1944. Since that time it has become widespread in the upper Midwest and Texas.  In the northeast, it has been confirmed in NY and western PA.  Just this year, 2016, two new locations were confirmed in NY by the Cornell University Plant Disease Diagnostic Clinic:  Central Islip on Long Island and Canandaigua in the Finger Lakes region.  The origin of this pathogen is not known.

So what does oak wilt look like? In the most susceptible red oaks, symptoms include wilt, browning of the tips and edges of the leaves beginning in the upper part of the tree, twig and branch dieback, and browning of the outer sapwood.  The fungus kills the tree by growing in the xylem vessels where water and nutrients are translocated from the roots to the crown. The fungal invasion results in the production of gummy blockages that prevent translocation.

oakwilt-leaf-michstate Photo credit: Michigan State University

The disease is spread from one tree to another in two ways, via root grafts and sap beetles. A root graft is a ‘fusing’ of roots of neighboring trees that allows for movement between them of water, nutrients, and, unfortunately, the fungus.  So trees growing in close proximity in forests, landscapes or along streets can share this disease readily.  Sap beetles are attracted to fungal mats that form under the bark of dead and dying trees. Bark cracks form as the fungal mats enlarge. Spores of the fungus and an odor attractive to the beetles are both produced on the mats.  Beetles come to feed there and sticky spores adhere to their bodies.  The beetles are strongly attracted to fresh wounds on trees (ie pruning or other wounds) and when they move to those sites after picking up spores, the disease is spread to a new tree.  The spore can only invade a tree via a wound.  Long distance spread can occur when infected logs are moved to new areas.

oakwilt-fungalmat-michstate

Oak wilt fungal mat under bark. Michigan State photo.

 

sap-beetle-uwisc

Sap beetles are often black with orange markings.  University of Wisconsin photo.

 

If you’re not sure how to tell red oaks from white oaks, here’s the most visible difference: Oaks in the red oak group have leaves with pointed lobe tips and those in the white oak group have rounded tips as shown below.

 

oak-red-white-leaves

Photo credit: University of Minnesota Extension

 

Browning and wilt can also be caused by drought stress.  If it’s oak wilt, remember that the browning will begin in the top of the canopy.  Red oaks will die within months; not usually the case with drought stress or even other pest and disease problems.

What should be done if you suspect oak wilt on trees in CT? Contact your state’s diagnostic lab as soon as possible for information on sample collection and submission.  You may send images via email for a quick look and to see if other causes of the symptoms can be ruled out.  The UConn Plant Diagnostic Lab can be reached at 860-486-6740 or by sending an email to joan.allen@uconn.edu.  The diagnostic lab website is www.plant.lab.uconn.edu. Your vigilance will help protect oak trees in CT and throughout New England!

J. Allen