DOC PREVIEW
700303

This preview shows page 1 out of 4 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 4 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 4 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

Whenslow freezingoccurs, water is slowlydrawn out of the cells and all freezable wateris crystallized in the intercellular spaces. Ifsuch a condition is not prolonged, the plant mayescape injury.Turf Killed at TimeofThawWhen freezing occurs, water is pulled fromthe cells and the cell wall is pulled inward. Theprotoplasm in the cell becomes plasmolized, orballed up. Unless the protoplasm is well sup-plied with bound or unfreezable water, it be-comes brittle. Upon thawing, water rushes backinto the cell through the highly permeable cellwall, and the protoplasm may be stretched andsubjected to shear forces sufficient to destroyit. Under these conditions, turf is killed at timeof thaw.Turf Killed While FrozenThe work done by Dr. Jack Le Bean, of Leth-bridge Experiment Station in Alberta, Canada,indicates that fungi in plants produce gaseswhile the plant is frozen. These gases may causedeath. This production of toxic gas and trafficon frozen turf are the two main causes of turfdeath while still in a frozen state.Turf Killed After ThawingMany of the common pathogens associatedwith winter injury are apparently very active,and their destruction may be most pronouncedjust after thawing begins and when the plantis striving to re-initiate growth.When frozen soil begins to thaw, heaving mayalso occur. Heaving may cause a large portionof the root system to be pulled off. If crowntissue h3s also been damaged, little of the plantis left to support continued growth, and deathoccurs when the immediate energy supply isexhausted.DesiccationDesiccation is the drying out of soil and planttissues. It may cause severe damage in winterif adequate moisture is not maintained. In theabsence of snow cover, moisture may be lostfrom frozen soil by sublimation. This means thatthe moisture may pass directly from solid togas without becoming a liquid which is of coursethe only form available to the plant. When thishappens, plants simply die from drought.Ice SheetsThe most comprehensive work on ice sheetdamage has been done by Dr. James Beard ofMichigan State University. Some of the mech-anisms of ice sheet damage suggested by Dr.Beard are the depletion of oxygen, the accumu-lation of carbon dioxide and the leaching ofcellular constituents. Although Dr. Beard hasthus far reached no definite conclusions on thematter, his work indicates that direct effects oflow temperature may be more important thanany of the mechanisms of ice sheet damage.What toDoWhen Winterkill Occurs1.Water lightly and regularly until the plantcan re-establish its root system.2. Where no plant is left, replant followingwhatever renovation is possible with spiker andperhaps some vertical mowing or vertical slicing.3. Gentle treatment of the turf as if the en-tire damaged portion were all new seedlings,which in effect it is, is called for.Winter injury has been so widespread andsevere recently that numerous experiment sta-tions have begun to study the matter morecritically. There has been a renewed interest insoil warming by the use of electric heatingcables and in the use of various types of cover-ings.Winterkil/:Learn The Cause, Improve The Cureby JAMES W. TIMMERMAN,Agronomist, USGA Green SectionWithin the last five years, golf courses in theNorthern United States have experienced winterinjury as severe as any in history.What are the causes of winterkill and what isknown of their destructive action?The ravages of winter are easily classed intosix categories:MARCH 1970ASSOCIATED ICE SHEET DAMAGEThe extensive damage suffered from icesheets during the 1961-62 winter seasonprom pted con sid era bIe resea rch. Investigatedcauses of ice sheet damage include:1.Oxygen suffocation under the ice sheet.32. Toxic accumulation of carbon dioxide and other breakdown products under the ice sheet. 3. Outward leaching of vital cellular constit-uents while submerged in water during thawing. 4. Outward diffusion of water from leaves encased in ice. 5. Direct low temperature injury. The work of Dr. James Beard at Michigan State University, however, suggests that injury from the first four causes above normally does not happen until after 75 days. Ice sheets of this duration rarely occur in the United States. Injury, therefore, is apparently caused by direct low temperature kill. Observations by Green Section agronomists conclude the following: 1. Poa annua is more severely injured than any other turfgrass found on northern golf courses. 2. A solid ice sheet must be in place 20 to 25 days before Poa is damaged. 3. Bentgrasses will subsist considerably longer. 4. Damage is aTways more severe on poorly drained soil which compacts readily. 5. Succulent turf experiences the greatest in-jury. DIRECT LOW TEMPERATURE INJURY Injury of this type is associated with freezing and thawing of water in the plant. Death results because of the harmful effects of ice crystals either within the cell or in intercellular spaces. In the case of intracellular (inside the cell) freezing, injury is caused by a mechanical dis-ruption of the protoplasm by the ice crystals. Generally, intracellular freezing always kills the cell. However, this apparently happens in nature only to unhardened plant tissue frozen rapidly. Hardened tissue undergo changes which resist intracellular freezing. These changes include: 1. A reduction of water within the tissue. 2. An increase in soluble carbohydrates. 3. A change in the type of proteins present. 4. An increase of bound water within the cell. When intercellular (outside the cell) freezing occurs, death may or may not result, depending on the degree the protoplasm of the cell is affected. Injury to the protoplasm from inter-cellular freezing is different from injury from intracellular freezing. When the plant freezes slowly, water is drawn from the cell into the intercellular spaces where it freezes. If enough 4 Severe damage to this green was caused by traffic allowed during a thaw period. water is drawn out of the cell, the protoplasmic consistency is increased until with extreme de-hydration it becomes brittle. Due to the water removal, the cell wall contracts and subjects the brittle protoplasm to tensions. Upon severe contraction the tension produced results in me-chanical damage to the protoplasm. Further in-jury can result if the plant thaws rapidly. When this happens, water rushes back into the cell and the protoplasm may be stretched and sub-jected to shear forces sufficient to destroy it. Hardened tissue, because of an increase in the bound


700303

Download 700303
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view 700303 and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view 700303 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?