Turf grass diseases

22 Apr 2012 Comments 0




Pennisetum Clandestinum (known as Kikuyu lawn grass) as a general host and Stenotaphrum Secundatum, also known as (Buffalo lawn grass).


Some Dematiaceous Hyphomycetes that cause lawn diseases are:

Leaf spot, Rhizome rot and Fading-out, Blight, Crown and root rot, Poa leaf spot, scald, and a host of diseases caused by Drechslera spp (which was formerly called Helminthosporium), also the disease called Fusarium spp, Curvularia spp, Bipolaris and Exserohilum spp. Each disease has its own related pathogens.


Epidemiology and disease cycle

These pathogens are active at all times, the grass blades, roots, lower stems rhizomes and / or stolons may be affected directly by fungus, mycelium bearing conidiophores and conidia. These pathogens survive unfavorable conditions (periods of very hot or cold weather) as conidia (spores) and as dormant mycelium in infected plant tissue and in debris. The fungi can grow saprophytic on dead tissue and produce spores profusely when dry debris is rewetted.


During periods of cool, moist weather the conidia may spread to healthy leaves or leaf sheaths by wind, rain, irrigation water, equipment, or feet of people or animals. When the leaf surfaces are moist and the temperature requirements are met, the conidia germinate quickly and

produce germ tubes that infect the leaves.


Different pathogens become active at different times according to temperatures and growing conditions. Lesions are produced, and additional spore production may occur on the dead and infected tissue in larger lesions.


The disease cycle occurs mainly during spring and autumn, while other pathogens continue the cycle during the warmer weather.


Physiologic changes in the plant heighten susceptibility to the disease when light intensity is low (shading by trees, clouds, etc), when movement of air is impeded, when the mowing height is lower than that recommended for specific turf grass being grown, when turf is fertilized excessively with nitrogen, and when hormonal type fungicides or herbicides have been applied to control other diseases and broad leaf weeds. In addition, large amounts of thatch provide a food source on which the disease can grow and produce spores.



If the lawn is badly affected, remove thatch if it accumulates to depths of more than 2cm. Rake out all dead material and thin lawn to get rid of sponginess. This should be done in early spring. Destroy all diseased plant material, grass cuttings etc.


Water should be applied thoroughly in the morning or at midday to wet the soil deeply but as infrequently as possible without causing stress. Avoid frequent short irrigations, especially in the latter part of the day or evening. During winter period do not water, only water when really needed.


Mow the grass as high as possible on lawns and commercial turf grasses; the minimum height should be 5 to 6cm to enable the grass to absorb day light (photosynthesis).


Avoid the over use of systemically trans located fungicides and herbicides for control of other diseases and broad leaf weeds these chemicals may accentuate the disease caused by Drechslera spp, Curvularia spp, Fusarium spp, Bipolaris and Exserohilum spp.


Apply fertilizers as needed to encourage moderate growth but avoid rates that cause excessive growth. It is especially critical to avoid over stimulating the growth of the grass in early spring and midsummer. Fertilize with 2:3:4 (30) The number (4) stands for the high potassium content which increases the plant's resistance to disease and promotes the plant's health and sturdiness. Alternate with 3:1:5 use 20 to 50 grams

per square m2. The exact proportions and amounts of fertilizers can only be determined host after soil tests are conducted. Be careful with the use of L.A.N (Limestone Ammonium Nitrate) or compost with high nitrogen content, such as mushroom compost, chicken manure, etc.


Apply KMnO4 (Potassium Permanganate) used as a fungicide. A purple-red crystalline salt, used as an oxidizing agent.


Dosage of use: 1 tea-spoon in 5-liter water over an area of 20 m2 lawn. Use a fine nozzle watering can or a high pressure spay can. The program is essential in March, April and May this can be suspended to September, when it should be repeated for approximately 2 months again, as required.


Alternate with CHLOROTHANIL a soft white-gray crystalline metallic element in a liquid form, used as a fungicide. It is obtained synthetically and is a byproduct and formulated by the oil industry. Spray particularly on the diseased or bare areas as the spores affects the soil as well as the grass. Dosage of use: 25 ml in 1-liter water and spot spray badly affected areas in the lawn.


Controlling the disease needs to be done immediately when there are signs of returning.

There are at this stage no guaranties of a permanent solution.


Create a better environment with PENAC "P" (Apply for our separate information sheet). PENAC "P" plant and soil catalyst, will stimulate the development of O2 (oxygen) generating microorganisms such as aerobic bacteria. PENAC comes in a form of a fine white mineral powder. It is chemically inert Dosage of use: 12 grams in 24-liter water will cover +/- 60 m2 area. It is relatively inexpensive. Positive results have been reported in horticulture and agriculture where all synthetic growth regulators, cosmetics, etc. are excluded.


A conversion process of developing a viable and sustainable agro-eco system over a period of time to organic agriculture is another option. If the farm or fields are not converted at once it should be done on a field-to-field basis, whereby full standards are followed from start to conversion on the relevant fields. The area of land being managed to the full standards will therefore progressively increase. It is recommended that a conversion plan is made and assessed periodically. Inspections must be made and updated when necessary.

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