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Issued By The 

UNITED STATES GOLF ASSOCIATION GREEN SECTION
P. O. Box 73 
Benjamin Franklin Station 
Washington, D. C.

SNOWMOLD INJURY TO TURF: One of the several causes of turf injury in northern 
sections of the United States during the winter and early spring months is the fung­
us disease known as snowmold. The name of this disease is something of a misnomer 
because snow is not necessary for its appearance, but it is important only in so far 
as it provides a favorable temperature and moisture for the growth of the fungi that 
may cause this type of disease. In some areas, however, such as the Pacific North­
west, the fungi grow actively in the winter in the complete absence of snow so long 
as there is an abundance of rain or mist.

In the early stages of the disease the fungus may appear as a thick, 
cottony growth covering certain more or less definite but irregular patches of turf 
ranging in diameter from one inch to several feet. Later, as the grass dries, these 
same patches appear grayish and dead, the spots in the final stages resembling those 
on turf infected with brownpatch. The disease may occur during fall, winter, or 
spring months but is usually first noticed when the snow is melting.

This is the time of year, however, to consider possible ways and 

means of preventing snowmold injury to your turf this winter or next spring. If you 
are growing grass in northern areas where snowmold is prevalent, it is advisable to 
use strains of grasses which are resistant to the ravages of the fungus. Some of 
the grasses which are particularly susceptible, and are therefore to-be avoided in 
such areas, are red fescue, Poa annua, and several strains of creeping bent such as 
seaside, Columbia and Inverness.

Fertilization with excessive quantities of nitrogen late in the fall 

has been shown to increase the susceptibility of any of the grasses to snowmold. 
Therefore, in regions where snowmold is likely to prevail, fertilizing should be 
avoided in the fall. In such regions, inorganic fertilizers are better than organ­
ic materials for late summer fertilizing because with the latter the nutrients are 
slowly available and feed the grass much later in the season than do the inorganic 
materials applied at the same time.

Covering the turf with such materials as manure, and straw in order 
to protect it from the cold should be avoided. The use of any such coverings which 
keep the grass wet after the snow begins to melt and the grass begins to grow will 
encourage the growth of the snowmold fungus. Snow falling on unfrozen ground will 
encourage the fungus both in late fall and early spring.

However, even when these precautions are taken, it is a good form 

of insurance to apply mercury fungicides now as a preventive treatment. Corrosive 
sublimate and calomel have been shown to control the disease effectively. These 
should be applied in late fall at the rate of 2 to 3 ounces to 1000 square feet. 
Either corrosive sublimate alone or a mixture of it with calomel will be satisfac­
tory. They may be mixed with sand and applied even after the first snow has fallen. 
Under certain conditions which are particularly favorable for the development of 
the fungus or where grasses are used which are particularly susceptible to the dis­
ease, a higher rate of 4 to 5 ounces to 1000 square feet may be necessary. In the 
Northwest where the winters are open, more nearly perfect control is obtained by 
applying repeated treatments at lower rates in fall, winter, and spring. At pres­
ent, no fungicide can be recommended as a substitute for the mercury compounds al­
though the latter are now unusually expensive.

October 1940

IMPROVE DRAINAGE NOW: One of the most frequent causes of winter injury to turf 
probably is inadequate drainage. Too often, the turf is weakened by poor drain­
age conditions during summer as well as winter. However, there are a number of 
factors which are involved in this problem particularly during the winter. Even 
though drainage may be good in the summer, the snow, ice, and frozen soil all 
combine to prevent the water from running off or penetrating the soil in the winter.

Alternate freezing and thawing is aggravated by poor drainage both 
on the surface and within the soil. The resulting heaving is particularly injuri­
ous to seedling turf. Usually such heaving is worse in heavy than in light soils. 
Therefore, before the ground freezes, an effort should be made to improve the 
drainage on areas which are recognized as being inadequately drained. This will 
not only reduce the danger from injury to turf during the winter but will speed 
up the run-off of water next spring when melting snows and spring rains bring the 
question of drainage to the fore once more.

GREY OR WHITE SODIUM ARSENITE: Sodium arsenite is available both in a white and 
a grey form. Both forms contain similar amounts of metallic arsenic and apparently 
are equally toxic, but the grey product is a trifle cheaper than the white. When 
applied by the dry method, the grey form is apparently just as satisfactory as the 
white. The grey form, however, contains 1^ percent more insoluble matter than the 
white and consequently does not dissolve so completely. When the grey product is 
to be applied as a spray, therefore, the solution must be filtered through a cloth 
or a fine screen or it will clog the pores in the spray nozzles.

ARSENICAL TREATMENTS AND BIRDS: The question is raised repeatedly as to whether 
or not the arsenical treatments which are commonly recommended in turf maintenance 
programs are injurious to birds. Several years ago, recognizing this possible 
hazard to birds, the Green Section cooperated with the office of Mr. McAtee of 
the Biological Survey in a study of the birds feeding on turf which had been poi­
soned with arsenate of lead.

For the test, an area of turf was selected which was badly in­

fested with sod webworms. These grubs were attracting large numbers of birds to 
the area. Before the area was poisoned the representative from the Biological 
Survey studied the habits of the birds and located all the nearby nests. Then 
liberal quantities of arsenate of lead were applied to the turf and a high per­
centage of the webworms were killed. The birds returned the.first day after the 
application of the arsenate but they did not eat nor carry to their young any of 
the poisoned webworms nor the earthworms which were poisoned by the same chemical. 
After that the birds went elsewhere for their food. The young birds in the' nests 
were watched and it was found that they all grew in a normal manner and left 
their nests without any sign of injury.

Similar observations have since been made repeatedly on the Arling­

ton Turf Garden. There have been occasions in which several hundred birds have 
been feeding there and within 24 hours after the poison was applied the area was 
abandoned by the birds, without any sign of injury to them.

Likewise, on many golf courses where arsenate of lead has been 

applied to greens, fairways, and even the rough, no dead birds have been found 
to indicate poisoning. At the same time, ground-feeding birds have continued to 
nest and raise their young on these courses with no evidence of harm from arsenic­
als. Apparently in regions where grubs or worms are sufficiently numerous to jus­
tify the expense of an application of arsenate of lead, the birds can usually find 
a plentiful supply of them in nearby areas which it has been impractical to treat.

The amount of arsenic applied to turf to selectively kill weeds 
is only a small fraction of that used in insect control. The Green Section is 
confident, therefore, that arsenical treatments to turf can be made to kill insects 
or weeds without introducing any menace to the bird population.

October 1940 

T.T.T. 2

FAIRY RINGS: Fairy rings may appear wherever turf grasses are found. They are 
caused by various fungi, one of the commonest being the edible mushroom, Agaricus 
campestris. The thread-like mycelia of these fungi grows 6 to 8 inches below the 
surface of the soil and their presence is not recognized until the fruiting bodies 
which are known variously as mushrooms, puffballs, and toadstools suddenly appear 
in a more or less defined ring. Each year the infestation gradually spreads out­
ward from a central point in an ever-widening circle.

The tightly interwoven mass of mycelium occurs in a circular band 

or ring. During dry periods the soil invaded by the fungus is dried and not easily 
moistened by showers or sprinkling, with the result that the grass wilts and often 
dies immediately above the mycelium. At certain seasons of the year the grass just 
inside and outside of the band of injured turf which marks the presence of the my­
celium is stimulated in some way by the fungus, so that it grows as though it were 
particularly well fertilized.

Fairy rings are usually considered as interesting curiosities, which 

is fortunate because no control for them has been developed as yet. This lack of 
control is due to the fact that unlike most disease producing fungi, the mycelium 
grows too deep in the soil to be reached by the fungicides which are usually fil­
tered out by the top few inches of soil. If it is necessary to rid the turf of 
them, as is the case occasionally on putting greens, the most certain method is to 
remove the sod in the affected area, take out the soil to a depth of 6 or 8 inches, 
and replace it with new soil and sod. However, the fairy rings are less conspicu­
ous and cause less damage on turf which is well-fertilized and properly watered 
than on that which is less carefully maintained.

FERTILIZING IN THE SOUTH: In the southern states the summer grasses tend to 
turn brown during short cold periods in the fall. If generous applications of 
fertilizers are made during these cold periods, they will encourage the summer 
grasses to actively grow again during intervening warm spells. Sulfate of ammonia 
applied at the rate of 3 to 5 pounds to 1,000 square feet will serve well for 
this purpose.

FALL LEAVES FOR COMPOST: This time of year one of the major jobs in turf main­
tenance is to keep ahead of the falling leaves. Once they are raked into piles it 
is much better to use them in making compost than to burn them. Not only is the 
latter method wasteful, but it involves a risk of leaving unsightly scars, even 
though they may be on outlying areas.

Decomposition of the leaves in the compost pile can be hastened by 

the addition of fertilizer materials. One of the combination of materials frequently 
recommended for this purpose is the following,- 70 pounds of sulfate of ammonia, 
25 pounds of superphosphate, and 55 pounds of finely ground limestone, to each ton 
of leaves. The leaves should be spread in a layer 6 inches deep, treated with this 
combination of fertilizers and watered before the next 6-inch layer of leaves is 
added. Such material, when well decomposed, makes excellent topdressing for turf.

SCREENING COMPOST: Since compost must be screened before it can be applied as a 
topdressing to turf, this should be taken care of when the compost is relatively 
dry and easily pulverized. Usually the compost is in this condition in late sum­
mer, but the pressure of other work which is more immediately necessary frequently 
makes it impossible to screen a good supply of it at that time. Hence, too often 
the screening is postponed until spring when it is needed again. Unfortunately at 
that time of year the compost is likely to be wet and soggy so that screening is 
impossible. It is wise, therefore, as soon as time permits in the fall, to screen 
enough compost and soil for next year’s demands for topdressing. Where practic­
able, a covering for such screened material is desirable during the winter months.

October 1940 

T.T.T. 3