How Does Your Garden Grow?

Information gathered from Alabama Cooperative Extension System

Lichen on Trees and Shrubs

Lichens are often blamed for the decline and death of shrubs and trees in Alabama landscapes. This is not too surprising because these unusual plantlike organisms are commonly seen on the exposed limbs and trunks of declining or dead shrubs and trees, especially azaleas, dogwoods, and pecans. Lichens are not responsible for the poor top growth or death of shrubs and trees. Instead, their appearance is often related to damage from environmental stress or poor management. Exposed limbs on damaged plants simply give lichens access to the sunlight they need for growth with little competition.

These often inconspicuous, hardy, and adaptive plantlike organisms are composed of two fungi and a green alga. This union or symbiosis produces a long-lived organism that does not look like the fungal or algal partners, all of which contribute to the growth of the lichen. The alga uses photosynthesis, like other plants, to produce food while the fungus supplies water and essential minerals and produces a structure that protects the alga from extreme environmental conditions. Together they thrive in some of the harshest environments on earth where few other plants and neither partner alone can survive.

Lichens colonize a wide range of exposed surfaces of limbs, stumps, fence posts, soil, rocks, and other living and nonliving objects. Lichens are firmly attached to these hard surfaces. They are most numerous on limbs and trunks of large mature trees and shrubs in full sun, particularly those plants with badly thinned canopies. Most lichens will not thrive on heavily shaded twigs and branches of healthy woody plants. Few lichens are found in areas with high levels of ozone, sulfur dioxide, acid rain, and other common air pollutants. Consequently, lichens are a good indicator of air quality.

Lichens are not generally considered plant pathogens. Lichenized forms (Strigula spp.) of the green alga Cephaleuros are plant pathogens. Strigula spp. is the causal agent of algal leaf spot of camellia, southern magnolia, and other shrubs although southern magnolia and camellia are the most common hosts. On leaves of camellia and southern magnolia, the lichen Strigula appears as numerous small gray-white crusty spots (figure 4), which later turn yellow and are shed. Leaf spotting and premature leaf shed may be unsightly, but this disease is not a threat to plant health.

Lichens are an indication of poor plant health. Good plant vigor is the best defense against the presence of lichens. Heavy infestations of lichens are most common on shrubs and trees in declining or poor health due to other factors. Following recommended establishment, watering, and fertility practices will promote the development of a thick leaf canopy, which will inhibit lichen growth on twigs and limbs. Better growing conditions and soil fertility may stimulate new plant growth and ultimately suppress the lichens. Light pruning of affected limbs will remove some lichens and stimulate new shoot growth that may help shade out the remaining lichens. Trees and shrubs in extremely poor condition will often not respond to better care and should be replaced. Refer to Extension publications “Pruning Ornamental Plants” (ANR-0258) and “Planting and Establishing Woody Landscape Plants” (ANR-0410) for additional information on pruning, planting, and maintaining shrubs and trees.

No pesticides are currently registered for the control of lichens commonly found on the twigs and branches of shrubs and trees. Kocide 2000 or Kalmore (1 level tablespoon per gallon) will control the lichen (algal) leaf spot caused by Strigula spp. on southern magnolia when applied every 7 to 14 days, starting with the unfurling of new leaves. Continue sprays until the leaves mature.

 

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Gardening Calendar

OCT-2021

October : Lawns

  • Perform a soil test to determine if limestone is recommended and apply anytime this fall.
  • If winter or spring weeds were a concern this year, apply preemergent herbicides.
  • Fertilize fescue lawns at 1 pound slow-release nitrogen per 1,000 square feet.
  • As fall rain returns, monitor for fungal disease in fescue.
  • In regards to mowing, mow until no new growth is noticeable.
Information gathered from Alabama Cooperative Extension System

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Daylily Donation

Three daylily plants were generously donated to Montgomery Botanical Gardens by the Huntsville Botanical Gardens and recently added to our Daylily Display Garden which was created and is maintained by the Montgomery Area Daylily Society. The three donated daylilies are:
 
MONTGOMERY (1985), hybridized by Grady Kennedy
OLIVER BILLINGSLEA (1996), hybridized by Larry Grace
 XIA XIANG (1987), hybridized by Oliver Billingslea
 

Join us on October Volunteer Day this Thursday, October 14!

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How Does Your Garden Grow?

Information gathered from Alabama Cooperative Extension System

Recycling Leaves

You can recycle leaves and other yard waste for use as mulch or make compost for use as a soil amendment.

In heavily wooded areas, leaves should be left where they fall. This natural leaf litter breaks down over time and adds nutrients for plant growth. In managed landscapes, leaves make an excellent mulch for outdoor plants and shrubs. Whole leaves may be used, but you can reduce their volume (to as much as one-tenth), and create a more uniform look by shredding or chopping them. Mulch conserves water, suppresses weeds, and moderates fluctuating soil temperatures that can disturb roots.

If your soil drains well (is sandy or loamy), spread up to 5 inches of chopped leaves on all garden beds and under all shrubs, hedges, and trees. This layer will settle down to 3 or 4 inches, the maximum application you can make without risking oxygen depletion in the soil. If your soil is predominantly clay, spread 2 to 3 inches for best results. By next autumn, when the next batch of leaves is about to fall, the previous year’s mulch will have decomposed almost completely.

Leaves can also be turned into compost. Compost is the product of the aerobic (in the presence of oxygen) biological decomposition of organic waste material under controlled conditions. Composting at home saves transportation and disposal costs and provides an environmentally sound way to manage yard waste. Composting offers you an opportunity to keep yard waste out of landfills and makes a valuable soil amendment from your on-site resources.

If you have a compost bin, fill it with shredded leaves in the fall and keep any remaining leaves in a holding bin or in plastic bags stored nearby. Mix a few shovelfuls of soil or finished compost into the pile at the beginning of the process to add microbial decomposers. As leaves settle in the bin, add another bag or two of shredded leaves. Adding sources of nitrogen, such as vegetable scraps, grass clippings, or a cup of a nitrogen fertilizer, to your compost encourages decomposition.

By spring, all leaves should be in the bin and decomposing into rich compost. Turn the compost periodically, and by early summer, it is ready to use as mulch or for tilling into a garden. Compost improves any soil for growing summer plants.

If you don’t have a bin, you can create a compost heap, which is simply a free-standing pile of leaves. A good, workable size is about 3 feet wide and 3 feet high. The size can vary according to the amount of leaves used.

A good location is important for a successful compost pile. The bin or pile needs good drainage, and water should be readily available. The compost pile should not be located against wooden buildings or trees, since wood in contact with compost may decay. If you notice strong odors from your compost pile, you probably need to turn it. Odors associated with composting are generally due to insufficient oxygen, too much nitrogen, or too much water in the pile.

A compost pile made up of nothing but whole leaves does not need turning. Leaves will mat together and slowly decompose in about 2 years. If you want to speed up the process, shred the leaves and turn the pile monthly. This brings the most decomposed material at the bottom to the top and shifts the least decomposed material to the hot, bottom layer of the pile. Add some water each time you turn the pile. The compost is ready to use when it is dark and crumbly like rich soil.

For the latest facts and figures about materials, waste, and recycling, visit the United States Environmental Protection website.

For more information on your garden, visit the Alabama Extension website, www.aces.edu.

 

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Beauty in the Gardens

One of our new Entrance Beds was created and is maintained by the Capital City Master Gardeners. The Marigolds are responding to the cooler weather with increased blooming. The summer annuals in the circular beds will soon be replaced with plants with fall and winter interest.  

Our next Volunteer Day is October 14, we’d love for you to join us!


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