Video: Evergreen Shrubs in the Fall

Video: Evergreen Shrubs in the Fall

Fall is the season for leaf color changes on many plants, but we are often concerned when we see evergreen plants with brown leaves. Learn what is normal browning for evergreens and when to seek more help from UF IFAS Extension Escambia County.

What Can Be Done To Prevent Tree Dieback?

What Can Be Done To Prevent Tree Dieback?

Tree dieback is a complex syndrome and slow developing. Dieback is essentially a process in which trees lose leaves and limbs. This usually occurs as a result of severe stress to the tree’s bark or root system, but could be a result of a declining life cycle.

It’s important to note that there is a significant balance between a tree’s root system and the number of leaves and limbs it can support.  For example, if a tree loses part of its root system, possibly due to disease or lawn equipment damage, the tree will forfeit a portion of its leaves. Dieback doesn’t happen overnight, though. It’s a slow process, with larger trees taking much longer time for signs of stress to emerge.  However, a large tree root system is very sensitive to damage, whereas a small tree will adapt quickly and is much more resilient to damage.  So, what can be done to prevent dieback in trees?

First and foremost, trees, like all living things, have a natural life cycle.  Regardless of how you care for your trees, dieback will occur. The most important management measure in extending the life of a tree is to protect the root system and bark.

With each passing year, a tree grows new bark in the rejuvenation process.  The bark replacement process inevitably becomes more difficult as the tree gets older and in turn the tree is more and more susceptible to dieback. If the bark becomes damaged, especially later in the tree’s life cycle, then fungi and insects have a much greater chance to cause serious harm. Treating bark damage with a wound dressing to prevent decay is the recommended procedure.

Lichens come in many forms and are commonly blamed for the decline and death of trees and shrubs, however they do not cause harm. Credit. Sydney Park Brown and Joseph Sewards, UF/IFAS.

A common misconception is that epiphytes, such as lichens and Spanish moss, are tree diseases. Epiphytes are known as “air plants” and thrive in the Panhandle. They survive on moisture and nutrients in the atmosphere and are harmless to trees. However, a tree that becomes inundated with epiphytes may be an indicator of excessive soil moisture, which may lead to root rot.

Lawn weed killers can have detrimental effects to trees, even if the application seems to be from a safe distance.  When using a weed killer near a tree’s root system, confirm on the label that the product is designed to kill green growth only. It can’t be overstated that excessively fertilizing an old tree will greatly accelerate the decline of the tree. Some may think this will stimulate a tree and extend its life, but instead it will do the opposite. Young trees can tolerate fertilizer applications, as they need crown growth. Older trees will simply become top heavy, and structural damage will likely occur.

Don’t forget, trees need space too.  A mature tree forced to occupy a small space will simply not adapt. Be sure to have adequate spacing when planting younger trees and shrubs in the vicinity of older trees. Also, keep your trees pruned away from touching structures and utilities.

Tree dieback is a complex issue to manage. By following these measures, you can help extend the life of your trees and continue to have a picturesque landscape.

For more information on tree dieback, contact your local county extension office.

Please visit Florida Friendly Landscaping, http://fyn.ifas.ufl.edu/, for more information on maintaining your landscape.

For more general  information on lichens, please see UF/IFAS EDIS document “Spanish Moss, Ball Moss and Lichens-Harmless Epiphytes” by Joe Sewards and Dr. Sydney Park Brown: https://edis.ifas.ufl.edu/pdffiles/EP/EP48500.pdf

UF/IFAS Extension is an Equal Opportunity Institution.

Controlling Cogongrass

Controlling Cogongrass

Over the last decade or so, the Panhandle has been overrun, and I don’t just mean by the summer beach traffic.  Rather, by an aggressive, exotic perennial grass that quickly displaces all native species, is not useful as a forage to wildlife or livestock, can spread by roots or seeds, and has no natural enemies.  If you own property in the Panhandle or spend any amount of time on its roads, chances are you have become acquainted with this worst of invasive species, Cogongrass (Imperata cylindrica).

A native of Southeast Asia, cogongrass was introduced into the US in 1912 around Mobile, AL as a hitchhiker in orange crate packing.  Then the 1920s, 30s, and 40s, it was intentionally introduced from the Philippines into other Gulf Coast states, including Florida, as a potential pasture forage for livestock.  Since then, cogongrass has become one of the most economically and ecologically important invasive species in the US and worldwide, infesting nearly 500 million acres and is now found on every continent.

Cogongrass in Calhoun County, FL. Photo courtesy of Daniel Leonard.

Cogongrass is easily identified in late spring, when the grass throws easily spotted fluffy, white-colored seedheads above the mats of grass beneath.  Additionally, patches of cogongrass are almost always noticeably circular in nature, radiating out indefinitely from the initial infestation.  A closer inspection of the grass will reveal light green leaves up to 4’ in length, with an off-center, silvery colored midrib (the primary leaf vein that runs from the base of the leaf to the tip) and serrated leaf edges.   Underground, cogongrass exhibits a dense underground root system that can reach as deep as 4’.  This feature is the primary reason cogongrass outcompetes other plants, withstands any drought, fire, or soil condition thrown at it, aids in its resistance to herbicide activity, and generally makes it very difficult to manage.

The first step in managing cogongrass is prevention.  If your property or the property you manage doesn’t have cogongrass, do everything you can to keep it that way.  While the species can spread distances through seed dispersal, it is much more frequently moved around by fragmented rhizomes hitching a ride on equipment.  If you or a contractor you’ve hired are working in or around an area with cogongrass present, avoid disturbing it with equipment and be diligent in monitoring the site for outbreaks following the job’s completion.

If you find cogongrass on your property, effectively eradicating it requires patience, persistence, and several years’ worth of herbicide applications.  Currently, of the hundreds of herbicides available for purchase, only two chemistries have been proven to be very effective in destroying cogongrass, impazapyr (Arsenal, Stalker, etc.) and glyphosate (Roundup, Cornerstone, etc.).

  • Imazapyr is an extremely effective non-selective, residual herbicide that controls a wide variety of weed species, including cogongrass. Just one or two applications of imazapyr can provide 18-24 months of effective cogongrass control, with follow up treatments required as needed after that.   However, Imazapyr has a major downside that limits its use in many settings.  Because it is a non-selective herbicide with significant soil residual activity, it cannot be used around the root zones of desirable plants.  Oaks, other hardwood trees, and most landscape plants are especially sensitive to imazapyr.  This herbicide is best limited to use in fields, waste/fallow areas, natural areas, and monoculture pine plantations – it is not appropriate in most residential and commercial landscapes.
  • The other option, glyphosate is a non-selective herbicide with no soil residual activity. It is often a better option where severe injury or death of desirable hardwood trees and ornamental plants cannot be tolerated.  However, due to its lack of residual soil activity, glyphosate applications on cogongrass patches will need to be repeated on an annual or biannual basis for up to five years for eradication of the infestation.

*Regardless of which herbicide you choose, controlling cogongrass is a multi-year affair requiring diligence and patience. 

For more information on cogongrass and for specific herbicide recommendations and application rates/timing for your site, please contact your local UF/IFAS County Extension Office.

 

Fall Preparation in the Garden!

Fall Preparation in the Garden!

Carrots need enough space so as not to compete for light, nutrients, or moisture. Photo by Full Earth Farm.

Photo by Full Earth Farm.

Yes, that’s right! We made it through the hottest part of the year and we are looking ahead to fall just around the corner!  I am excited to be discussing September and what we can do to prepare for fall in the garden.  As the nighttime temperatures start to cool down, we are given many more options.

For annual color plantings in September, try Ageratum, Celosia, Zinnias, and Wax Begonia to add fall color to your landscape.  Bulbs will also add color, texture, and pattern to a bed.   If you have some extra space, a variety of elephant ears could really accent a bed or you could always go with the classic calla, narcissus or zephyr lily.  Popular vegetables to plant in North Florida in September are broccoli, carrot, cabbage, and collards. See Vegetable Gardening in Florida This is also the time of year to establish strawberry plants.  Some great herbs to get started are Mexican tarragon, mint, rosemary, and basil.

Strawberries growing on "plastic" to protect them from water splashed fungal spores found in soil. Image Credit: Matthew Orwat UF/IFAS Extension Washington County

Image Credit: Matthew Orwat UF/IFAS Extension Washington County

There are many things that can be done in your lawn during September.  Monitoring your lawn for its health and potential insect pests is important this time of year.  Common insects to scout for are fall armyworms, chinch bugs, mole crickets, and sod webworms.  The last fertilizer application should be done by the middle to end of September.  Make sure you choose a fertilizer with little to no phosphorus unless a soil test shows differently.  To maintain a healthy lawn, avoid weed and feed products and only apply herbicides in areas with high infestations of weeds. Weed and feed products are not recommended because the timing of when to fertilize and the timing of the weed killer is not always the same. The best management practice is to use a separate treatment for weeds and when possible spot treat weeds.

If you already have bulbs in your landscape from previous growing seasons, this is the time to divide and replant those that are big.  You can also add organic matter to new planting areas. Continue working on your vegetable plants and prepare them for either transplants for a fast start, or plants seeds for more variety.  Throughout your landscape, it is important that plants are getting the right amount of water as we go in and out of wet and dry weather this time of year.

October will be here before we know it in just a couple of weeks. Look out for the next article to come.  We will be getting into the cooler nights and more options for planting vegetables and herbs!

Plant Growth Abnormalities

Plant Growth Abnormalities

Every so often while I am enjoying a walk through the garden, I notice a growth pattern on a plant that is just not normal.  One of the more interesting patterns I see is called fasciation.  This is a distortion of plant tissue that often causes flattened, curved, or the thinning of plant tissues.  I recently noticed this on the stem of a Coral Porterweed in the Escambia County Demonstration Garden.  The leaves were a normal shape but several inches of the stem were flattened and curved.

The distorted stem tissue of a Coral porterweed. Photo by Beth Bolles, UF IFAS Extension Escambia County.

So what is causing this type of growth pattern?

The most common cause of fasciation is usually some type of genetic mutation in the growing points of the plant.  The other possible causes could be a physical injury to new tissues, a bacterial infection, chemical injury, or even an insect injury.  Fasciation will be random in its occurrence and many gardeners may never have it occur on a plant in their yard. I have seen it on both woody and herbaceous plants in my own yard and in the demonstration gardens.

If you see a plant exhibiting this distortion of growth, you don’t need to take any action.  If the growth is unsightly to you, prune out the affected plant tissue.  It is probably best that you not propagate material from an affected plant just to prevent any transfer of the distortion to a new plant if the cause is genetic or from a living organism.