Question
Jim,
My challenge is a brown dusty residue on my lawn which is Hybrid Bermuda.When I walk out onto my lawn my feet get covered in this brown colored dust. It's basicly easy to wash off with water but is a real nuisance.This appears to occur mainly in Spring and early Summer. It's real heavy right now. My dog doesn't even want to go in the yard.My lawn is otherwise healthy and for the most part weed free. I (my wife) mows the lawn once a week and we water using an automatic (Torro)inground sprinkler system three times a week (yes it is timed to run like clockwork. But after reading another article about only running it when the grass looks like it needs it I'm going to vari my watering times). We live in Central Texas and it gets hot here with occassional high humidity.
I've read a paper from Texas A&M University that this problem is cured by using a broom or high pressure water spray throughout the yard when symptoms appear.  Local Nurseries want to SELL me everything under the sun to correct this problem. What's your advice to get rid of the Slime Mold dust and control it's emergence.
Looking forward to receiving your advice soon.
Thanks,
K-MAN

Answer
Hi K-Man,

Your 'slime-mold' problem is most likely a category of fungus diseases called 'Rusts and/or Smuts'.

Some of the brownish rusts can occur often an an area where species of Malus[Apple, Pear, Plum], Rosa [ Roses], Fragraria, Duchesnea [Strawberries], and etc grow.  Fungi which cause rust/smut-like syndromes are many but most belong to the Genera 'Puccinia', 'Tranzschelia', 'Uromyces', 'Ustillaga',...and etc.

Some variants may infect turf grasses, although I have never encountered this myself.  "Wheat rusts" are a serious global agricultural problem, and wheat is a grassy-plant.

Using key-words 'Cynodon rust infection' at the search engine GOOGLE.com, it returns 157 web-pages that discuss rust infection of Bermuda grass (Cynodon specie).  Some of these are PDF files and you may find more information by scanning these resources.


A super-hybrid cultivar of a grass plant may be particularly susceptible to these types of disease agents while extra-immune to others.  You may find more information by contacting your State's Department of Agriculture and the Plant Pathology Director.

 These diseases of plants can spread vigorously to infect a variety of  foliage plants from onions to mums, and you may have to work hard to find the main source of the fungus' spores that help it to spread. It may have a reservoir host in the neighbor's rose bushes which can continue to infect plants in the area as the microscopic spores can be spread by the wind.

The causative microbe makes tiny redish-brown to orange dots on the leaves which tend to form a dry powdery rusty powder (spores)  that can be easily picked up an shoes and anything that rubs against the infected vegetation.

Fungi reproduce by microscopic SPORES.  As with weeds and their seeds, working to break the reproducing cycle by eliminating the spores and reproductive phase of the fungus is the best way to control it.  Rakes and tools, including the lawn mower should be sufficiently cleaned with a bleach solution to reduce the human caused spreading of the spores.
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If you can verify a FUNGUS DISEASE:
Your local garden center should have a variety of FUNGICIDE chemicals to treat a fungus infection of the grass.  Some fungal infections can spread very fast and destroy vast areas in short order so do not waste any time in treating a fungus infection once diagnosed.
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FUNGICIDES containing

Maneb,
Zineb, or
Mancozeb

....Used at two-week intervals or as necessary should control this type of problem.

If possible,...at the end of the growing season use a CONTROLLED BURN of the blanched vegetation-lawn to attempt to sterilize the top-soil.  With Bermuda grass, this burn-off should not destroy the lawn which will return after dormancy from its root-node clones.

If the disease appears on certain perennial shrubs and plants every year, destroy the plant and remove it as a source of the spores in the area.

Any fungus disease which may threaten agricultural crops or one in a rural area near farming concerns should be considered a serious problem to control. Fungus diseases cost the consumer billions of dollars per-year.
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A heat stressed BERMUDA and other grass type lawns with HIGH THATCH accumulation and over watering may  have a FUNGUS OUTBREAK.  Keep thatch removed and composted to re-cycle to the lawn's hot spots every year before the heat arrives; this improves the top soil and also adds to soil fertility.

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Turf grass FUNGUS outbreaks are relatively common and often fast spreading.
Work fast to avoid losing large areas infected with the phytopathogen.

Visit this website and link to "Lawns" for IMAGES of many turf grass diseases and their diagnosis:

http://plantpathology.tamu.edu/Texlab/index.htm

BROWN-PATCH DISEASE Website: http://plantpath.unl.edu/peartree/homer/disease.skp/Hort/Turf/Tubrnpt.html
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Since fungal problems in lawns are most often associated with too much watering, I include here a short article about watering the lawn:

Regular "Clock-timed" watering causes a "spoiled, shallow and weak root system" unable to cope with hot weather conditions.

ABOUT WATERING:
Unless you have a COMPUTER CONTROLLED IRRIGATION SYSTEM, i.e. one which automatically accounts for not only how much water rains are supplying to the lawn but also keeps a record of quantities applied to the lawn, DO NOT totally water your lawn with clock-timed regularity.  This can be a big mistake.

It is a common error with watering and sprinkler systems in particular to water with clock-timed regularity .  Lawns are best watered on a visually inspected and "as needed" system.  You should know how much water your sprinkler system delivers and also have a rain-gauge to help keep watering to within 1-3 inches per week.  Climate and weather factors of humidity, barometric pressure, winds, and micro-climates, soil drainage-physics etc., can make clock-timed watering more than in-efficient and un-reliable. A well hydrated stand of turf grass should bounce back when compressed by foot traffic; it should also be able to go several days between soakings in mild weather...this promotes deeper rooting and helps to get by in dry times. A single good deep soaking is better than frequent smaller waterings.

Watering at nights is usually more practical and efficient.  The idea is to NOT lose water by winds and evaporation effects which are usually less intense at night.
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Again, excessive moisture in a high nitrate-fertile cool top soil can cause fungal blooms and diseases; do not contribute to these conditions by over-watering or over-fertilizing your lawn when the turf grass is in a low metabolic state and not readily up-taking the salts.
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I Hope this has answered your question(s)!
Have a fantastic Summer!

Visit my Lawn & Gardens webpage for more Lawn and Garden Tips, Facts and Links:
http://hometown.aol.com/eilatlog/lawnol.html

Your Questions and Comments are welcome at ALLEXPERTS.com

___ Jim Gibbs,
     Microbiologist.