Why do leaves change color in the fall? When leaves appear green, it is because they contain an abundance of chlorophyll. There is so much chlorophyll in an active leaf that the green masks other pigment colors. Light regulates chlorophyll production, so as autumn days grow shorter, less chlorophyll is produced. The decomposition rate of chlorophyll remains constant, so the green color starts to fade from leaves.

At the same time, surging sugar concentrations cause increased production of anthocyanin pigments. Leaves containing primarily anthocyanins will appear red. Carotenoids are another class of pigments found in some leaves. Carotenoid production is not dependent on light, so levels aren't diminished by shortened days. Carotenoids can be orange, yellow, or red, but most of these pigments found in leaves are yellow. Leaves with good amounts of both anthocyanins and carotenoids will appear orange.

Temperature affects the rate of chemical reactions, including those in leaves, so it plays a part in leaf color. However, it's mainly light levels that are responsible for fall foliage colors.
​
Sunny autumn days are needed for the brightest color displays, since anthocyanins require light. Overcast days will lead to more yellows and browns.

​The close of the gardening season is always bittersweet. Though there are few more beautiful places on earth than Wisconsin in the autumn, it’s hard saying goodbye to the lush, green world for one that's cold and white. Now it's time to reap the season's most abundant crop: leaves.

One of the very best sources of organic matter is autumn leaves. Leaves are packed with trace minerals that trees draw up from deep in the soil. When added to your garden, leaves feed earthworms and beneficial microbes. They lighten heavy soils and help sandy soils retain moisture. Leaves make an attractive mulch in the flower garden. They're a fabulous source of carbon to balance the nitrogen in your compost pile. And they insulate tender plants from cold.

Here are 7 ways to put autumn leaves to work.

​If you are traveling in the Philadelphia area I highly recommend this list of gardens, all quite different.  Seeing woodland spring ephemerals in different settings taught me a new appreciation for what I tend to take for granted here at home.   Anytime during their long growing season these gardens will teach, display and provide pleasure to their visitors.  

​Morris Arboretum – As the name implies the arboretum is a teaching and research facility of the University of Pennsylvania.  It is set on the historic grounds of the summer home of John and Lydia Morris.  They have informative displays of trees, shrubs, and woodland perennials.  

​Longwood Gardens – One of many du Pont family gardens in the area.  The gardens are spread about on 1,100 acres of highly manicured display gardens.  We were there for six hours, more than enough time to see almost everything and spend time in their excellent garden shop.  According to their website they raise 75 percent of the plants used in their displays onsite producing about 110,000 plants of 1,000 different varieties.  Nearby is Kennett Square, a tidy small town with many retail shops and restaurants. 

​Mt. Cuba Center – The Center is set in the rolling hills of the Delaware Piedmont near Wilmington.   The property was developed by Mr. and Mrs. Lammot du Pont Copeland.  Mrs. Copeland is quoted in their intention for the property: “I want this to be a place where people will learn to appreciate our native plants and to see how these plants can enrich their lives so that they, in turn, will become conservators of our natural habitats.”.  If you go, I recommend scheduling a tour by one of their very knowledgeable tour guides.  If you can’t go to Mt. Cuba Center, you can still learn much by going to their website.  I have bookmarked as one of my favorites the native plant finder.  

​Winterthur – The home of Henry Francis du Pont, the 1,000 acres near Wilmington, DE includes 60 acres naturalist gardens, a research library, shops, museum, and the mansion chock full of American textiles and furniture.  The gardens are more in the background of Winterthur given all the other attractions of this property.  

​Chanticleer  - This garden was the last we visited, and I think the best.  Chanticleer is set on 47 acres of the former home of the Rosengarten family, members of the family still guide the foundation that manages the property.  This unique property employs seven Horticulturists who are each responsible for an area of the grounds.  Chanticleer advertises itself as a pleasure garden and definitely lives up to that name.  We felt as if we were invited guests, the horticulturists and grounds staff were about the grounds ready to answer our questions.  

What a treat to have visited these gardens, each one unique in its own way.  And the Winnebago Master Gardener Volunteers are wonderful traveling companions.  

​Author:  Sue Reinardy, UW-Extension Master Gardener Volunteer

The trees most likely to die from oak wilt infection are in the red oak group, including northern pin oak, northern red oak, red oak and black oak. The white oak group is more likely to survive infection and includes bur oak, swamp white oak, white oak and English oak.
Tree paint or wound dressing is not normally recommended on pruned or wounded surfaces, but for damaged oaks an immediate light application of these products may be the only defense against oak wilt infection from April through July.
Pruning in spring can be damaging to any deciduous tree because their energy reserves are low as they produce new buds and leaves following the winter months. In general, the best time to prune is in winter when trees are dormant. 
As of January 31, oak wilt has been found in all Wisconsin counties except Ashland, Iron, Forest, Taylor, Door, Kewaunee, Calumet and Manitowoc counties. Several of these counties contain the highest abundance of healthy and productive oak forests in the state. Taking recommended precautions will help keep them that way for years to come.
Oak wilt and other diseases move easily on or in firewood logs year-round, so keeping firewood local, or purchasing Wisconsin-certified firewood, is another important component of protecting trees and keeping forests healthy. Visit the DNR firewood page for more information and a directory of certified firewood vendors.
More information, including a recently released oak wilt video, is available at the DNR oak wilt page. Additional information about proper pruning techniques is available from community foresters or through DNR resources such as this tree pruning poster. 

​Each season Master Gardeners answer a plethora of questions for the public about gardens, turf, trees, flowers, vegetables, insects, and plant diseases. Some people have methods of gardening that have been passed down through generations that have no basis in fact and can, in fact, be downright detrimental to the landscape.

One very common practice is using salt for weed control in an asparagus patch. This old practice involves pouring salty water or granular salt in among the asparagus plants to kill the weeds.  While asparagus is deep-rooted and has a higher salt tolerance than shallow rooted weeds, this is still a poor practice.  The salt destroys soil structure, creates a crust on the soil surface, and results in poor water penetration.  Ultimately it will kill the asparagus along with the weeds.  Mechanical (shallow tilling or hoeing in the spring), cultural (applying mulch), or chemical (using preemergent herbicides) are all superior weed control methods.
​
Epsom salt application is another favorite of the garden misapplications. Epsom salt is high in magnesium and some gardeners use it generously when growing roses, peppers, and tomatoes.  In reality, unless the soil is extremely deficient in magnesium, it will not be of any benefit.  Even then, the application may result in environmental harm that negates any benefit. A soil test would be the first line of defense to determine if any deficiency exists.  In that unlikely event, an addition might be necessary, but Epsom salt would be a poor choice for an amendment.   Magnesium is not a macro element needed for ideal growth.  Healthy soil and the three major elements, nitrogen, phosphorous, and potassium, will produce ideal growing conditions.

A common misconception when planting a tree or shrub is to dig the planting hole twice as wide AND twice as deep as the root ball. Only half of that statement is correct.  The hole should be twice as wide, but only as deep as the root ball itself.  Deep planting leads to stress, decline, and eventual death of the tree.  Contrary to popular opinion, tree roots do not grow deeply like a carrot, but they spread widely.  They will extend as far, or farther than the tree canopy.  Ninety to ninety-five percent of the roots will be within the first three feet of soil, and fifty percent will be within the first foot.  When planting a new tree, identify the first set of primary lateral roots and locate them at or near the soil level.

Another mistake is to add compost to the planting hole. Roots prefer to grow in this nice, soft soil and will curl around and try to stay in the area instead of spreading out.  This will lead to girdling and eventual tree death.  Instead, backfill the hole with native soil.
​
The last fantasy is a potentially deadly one: organic pesticides are not as harmful as synthetic ones. Keep in mind that arsenic, snake venom, and E. coli are all organic, and all can be deadly.  A pesticide is defined as “any substance or combination of substances intended for preventing, destroying, repelling, regulating, or controlling pests.”  This covers both organic and synthetic pesticides and includes herbicides, insecticides, and fungicides.  The perception is that organic pesticides are gentler to the environment.  However, if improperly applied, organic pesticides containing pyrethrins (a compound extracted from chrysanthemums) can be toxic to both humans and pets.  Rotenone, another organic compound, can be hazardous to aquatic life.  All of them are harmful to beneficial insects.

To determine relative toxicity on any pesticide label, look for the signal words “Caution” (least toxic), “Warning”, or “Danger” (most toxic). However, these words do not give an indication of environmental harm, only toxicity. In any case, use according to label directions.

When trying to determine if a practice is sound or is based on questionable data, always use university based research. Find sites that end in .edu or .gov when using the internet as a resource.  Consult the County Extension Office or a Master Gardener for assistance.
​
Happy Gardening.
Carol Shirk
Certified Master Gardener
Original Post at:  ​https://dodge.uwex.edu/2017/04/ask-a-master-gardener-garden-facts-and-fantasies/