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28 Cards in this Set

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  • Back
Concerning Fairy Ring, what are the 3 types and describe each.
Type 1: Contains a zone of dead grass with an outer zone of stimulated grass, which may or may not produce basidiocarps. The zone of dead grass may also contain an inner zone of stimulated grass.

Type 2: Contains only a ring of stimulated grass growth, which may or may not produce basidiocarps.

Type 3: Contains a ring of basidiocarps which do not affect the growth of the grass. Only appear briefly when enviromental conditions are met.
Concerning Fairy Ring, what leads to the stimulated growth in Type 1 and Type 2?
As fairy ring mycelium grows outwards it decomposes organic matter in the soil, which releases nitrogen. this accounts for the outer ring of growth. The inner ring of stimulated growth comes about from older mycelium being decomposed by microbes in the soil.
Concerning Fairy Ring, what causes the death of turf in Type 1?
The exact cause of the death is not known, but there are many ways it ca happen.
1.) Soil moisture could be too low. this can occur from a build-up of mycelium in the soil, causing the soil to become hydrophobic.
2.)Nitrogen might build up in the form of ammoinia to leathal concentrations.
3.)Nitrogen might become used up and thus their is not enought o support life.
4.)The fungus might produce toxins such as hydrogen cyanide and ethylene.
5.) Roots might be infected by the mycelium.
6.)The degradation of te mycelium might lead to the production of substances that lead to hydrophobic soils.
7.)The grass becomes so weakened that it dies from other enviromental conditions.
When is injury from Fairy Ring most severe?
When fertility and soil moisture are low. Thick thatch layers and turf grown in sand also cause severe conditions.
Explain the use of fungicides to control Fairy Ring and whether they are successful.
Limited success has come from their use. they usually fail because they are usually water-insoluable and are difficult to distibute through the infected soil profile. Mixing them with wetting agents and drenching the turf at 4-6 week intervals can be effective.
What practices can be done to ensure some effectiveness when using fungicides (and wetting agents)
Core aerate (or spike) and pre-irrigate.
What are other ways of controlling Fairy Ring?
Turf destruction through soil fumigation, soil replacement, and soil cultivation and mixing.
What is the best way(s) to prevent Fairy Ring?
Thatch control, irrigation, and fertilization.
What are some ways of masking the damage of Fairy Ring?
If it is Type 3, simply remove the Basidiocarps. If dealing with the other two types, irrigate deep into the soil and apply moderate amounts of nitrogen. Aerification and wetting agents enhance the irrigation of the soil profile. Be careful also when applying nitrogen. Applying to much nitrogen can enhance the symptoms of Fairy Ring. Weed control might also come into play if they invade the dead areas of the turf.
What species of grass is Spring Dead Spot most important in, in North America?
Bermuda grass and can also occur in Buffalograss
What are the symptoms and signs of Spring Dead Spot?
Circular, bleached, dead grass in spring when plants are beginning growth. Circular depressed areas might also be evident before green up. These patches can be up 3 ft in diameter and tend to reappear and expand in the same area of 2-3 years. After these 2-3 years, grass or weeds begin to grow here, and they begin to take on a ring look or even a serpentine look if the "rings" coalesce. The fungi that causes Spring Dead Spot produces dark mats of mycelia which can be seen on infected roots or stolons. Ascocarps are occasionally found as well.
Concerning Spring Dead Spot, explain the regrowth in the dead spots after 2-3 years.
The regrowth is either weeds or new Cynodon plants. If its new Cynodon, the grwoth tends to be extrememly slow and the plants are stunted. This occurs because of a toxin that is left behind in these dead areas.
Where can algae be found?
On overly wet soils.
What problems does alage cause?
It prevents the exchange of gas bewteen air and soil. It may also induce chlorosis and turf thinning.
What are some management practices that can be done to control algae?
1.)Reduce Shade
2.)Avoid excessive or low fertilization
3.)Improve soil drainage
4.)Alleviate compaction
5.)Mow high to increase density
What are some fungicides that can be used against alage?
Mancozeb and Chlorothalonil
What are some chemical abiotic diseases?
2.)Animal Urine and salts
4.)Nutrient defieciencies
5.)Air Pollution
6.)Chemical spills
What are some mechanical abiotic diseases?
1.)Mower Injury
3.)Leaf and Crown Bruises
4.)Abrasive Injury
What are some physical abiotic diseases?
2.)Water and Ice
3.)Shallow Soil
4.)Soil Compaction
6.)Trees and Shrubs
What are slime molds sometimes confused with and how do you tel them apart?
Stripe smuts. The difference is when you wipe away stripe smut, it has shredded the leaf tissue while the slime molds leave the blade intact.
What are the symptoms of Pythium Foliar Blight?
Circular spots, usually 2-5 cm, sometimes up too 15 cm. Smaller circular spots on short grass, such as Agrostis and Poa, willhave a orange or bronze color and be 3-8cm. Larger irregular spots on longer grass, like Lolium, Festuca, and others may either be copper colored or have a gray water soaked look. Sometimes appear in streaks following water drainage patterns or paths of mowers and other equipment. These spots look water soaked and dark in early morning and feel greasy when rubbed bewteen the fingers. If humidity remians high lon enough, especially at night, leaves will collapse and become matted and mycelium will begin to grow. "Frog eye" look as well. In cooler conditions when fungus is still active, may take on the look of dollar spot on the fringe of patches,e xcept their is no tan line on the lesions and microscopic views show oopspores, spornagia, and coenocytic mycelium.
What enviromental conditions favor Pythium Folair Blight?
Hot (86-95F) Humid (90%+ for 14hrs+) or wet conditions with warm nights (min temp of 69f). Lush, dense grass growing under high N conditions. Alkaline soils may also increase severity.
What are some management practices that can be done to prevent Pythium Foliar Blight?
1.)Improve your soil drainage
2.)Increase air ciculation to promote drying
3.)Avoid mowing wet grass
4.)Avoid excess watering
5.)Manage turf to prevent lush rapid growth
What turf is most susceptible to Powdery Mildew?
Festuca and Poa in low light and poor circulation condtitions.
What are the symptoms of Powdery Mildew?
At first, isolated colonies of whitish mycelia on leaves and sheaths which then begin to spread to cover most of the leaf surface with superficial gray to white wefts of mycelium that appear powdery or dusty. As the area begins to grow, it begins to look as though the area was dusted with flour or lime. Older leaves are usally infected more then younger leaves. Heavily infected leaves begin to turn yellow then brown, then die. They also tend to die from other enviromental conditions. Cleistothecia may form as well with the age of the mycelium.
What conditions favor Powdery Mildew?
Cool, humid, cloudy periods, with temperatures between 41-72F (Spring and Fall). Most severe when there is heavy shade and poor air circulation. Times like these, Poa pratensis is highly susceptible especially if heavily fertilized with N.
What are some management practices that can be done to prevent Powdery Mildew?
1.)Reduce shade
2.)Increase air circulation to dry turf foliage
3.)Use resistant cultivars
What fungicides can be used against Powdery Mildew?
The DMI's and Heritage and Insignia