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Issued By The

UNITED STATES GOLF ASSOCIATION GREEN SECTION
P. O. Box 73 

Benjamin Franklin Station 
Washington, D. C.

Dollarspot frequently becomes prevalent in May, so it
DOUARSPOT CONTROL: 
is wise to be on the alert for it in your bent tuff now. Early attacks are 
frequently mild and may be ignored, but it is well to apply control treat­
ments before serious injury develops, as it may take several weeks for grass 
to recover from serious attacks. When bent turf is protected by a generous 
dose of mercury in May the succeeding attacks of dollarspot and brownpatch 
are less likely to cause serious damage before additional treatments can be 
applied. The most economical and lasting of the mercury fungicides used 
to control dollarspot is calomel. The May treatment with calomel should be 
at the rate of 3 ounces to 1,000 square feet.

Excessive watering during May and early June,
AVOID EXCESSIVE WATERING: 
just like excessive rainfall earlier in the spring, encourages the develop­
ment of a lush top growth and a shallow root system, both of which may invite 
disaster during the hot, sultry summer months which follow. Much serious dam­
age to turf during the summer months can be attributed directly or indirectly 
to excessive watering.

In May and June the adult beetle (May beetle or June Bug) of

WHITE GRUBS: 
the common white grub is active and laying eggs for the next brood of white 
grubs. These well-known beetles spend the nights in trees, where they feed 
on the young foliage. They seem to prefer the white or burr oak foliage but 
are also found in such trees as hickory, poplar, elm, willow, locust, ash, 
walnut, or even pines. The females fly down to the turf, particularly in the 
early morning hours just before daylight, and immediately burrow into the soil 
and deposit their eggs. They do not fly far from the trees which they inhabit. 
Consequently, the heaviest.grub infestation appears in the immediate vicinity 
of trees which have been hteavily infested with beetles.

In most species, the beetle spends two winters in the ground 

in the grub stage and one as a dormant beetle. After the third winter it 
emerges as an active flying beetle and lays the eggs from which the young 
grubs soon hatch. The life cycle of these species, therefore, covers 3 years. 
It has been found that the white grubs appear in large broods in certain sec­
tions of the country every third year as a result of a large brood of beetles 
the preceding year. Brood A appeared in 1936 as a result of a heavy infesta­
tion of beetles in the spring of 1935. Brood C appeared in more limited areas 
in 1935 from beetles which appeared in 1934. According to predictions, the 
beetles are scheduled to appear this spring for the 1941 infestation of Brood 
C of the white grubs. Maps showing the districts of greatest abundance of 
Broods A and C have been published in the April, 1939 issue of TURF CULTURE.

At this season of the year it is well to watch for the beetles 

at night or in the very early morning. Wherever they are observed in large 
numbers, grub injury within the next few months and particularly next year can 
be anticipated. Important turf in such infested areas may be treated with 
arsenate of lead at the rate of from 5 to 10 pounds to 1,000 square feet dur­
ing the summer to poison the young grubs before they do serious damage to the 
turf.

May 1940

In regions having excessive rainfall during
RAINFALL AFFECTS TURF MAINTENANCE: 
the spring months, turf is apt to be shallow-rooted and therefore more likely to 
be severely injured by hot, dry weather in early summer. Also, grass with a 
shallow root system will not recover so rapidly fhom fungus attacks as will turf 
with a deeper root system. Therefore, after excessive spring rainfall, attacks 
of fungus diseases should be controlled as promptly as possible.

This year during the months of February, March and April the average 

rainfall exceeded the normal for those months in 35 states. In some sections the 
excess was particularly large as, for instance, in the New England and Middle 
Atlantic states, where April rainfall ranged approximately between 35 and 70 per­
cent above normal. It is interesting to note that on the opposite side of the 
country the three Pacific Coast states also experienced excessive spring rainfall, 
that in February having been from 85 to 100 percent above normal.

In certain regions receiving excessive rainfall last

LEAFSPOT ON BLUEGRASS: 
month, conditions have been particularly favorable for the development of the fun­
gus which causes the leafspot disease on Kentucky bluegrass. In such regions it 
is not uncommon to find large brown areas appearing on otherwise good stands of 
Kentucky bluegrass. Although many of the leaves in such areas have been entirely 
killed, close examination of some of the more recently infected blades will reveal 
typical leaf spots. Unfortunately there is as yet no cure for this disease although 
cultural practices will help to speed up the recovery of the grass. It is well to 
keep the grass on such infected areas of turf cut as high as possible and well fer­
tilized until it has recovered. So far, the chief hope in preventing the occurrence 
of this disease is the selection and propagation of resistant strains such as some 
of those which we have selected and are propagating at present at the Arlington 
Turf Garden. No seed of such selections is as yet available.

MERCURY FUNGICIDES

The recent rapid’ rise in price of calomel and corrosive sublimate has 

raised the question of the advisability of substituting other mercury products for 
them as turf fungicides. The experimental work of the Green Section showed many 
years ago that the value of the various mercury fungicides in turf disease con­
trol was largely dependent on their mercury contents. The percentage of mercury 
contained in several fungicides in common use is given below:

Mercury Compound 

Approximate Percentage of Mercury

Oxide of Mercury 
Calomel 
Corrosive Sublimate 
Fungol 
Curex 
Special Semesan 
Semesan 
Nu-Green 

92
85
74
33
20
18
17
11

Mercury ’has always been the most expensive ingredient in this group 

of fungicides and those which contain the most mercury have naturally shown the 
greatest rise in price during the last year due to the steadily mounting price 
of mercury, or quicksilver as it is known in the trade. On the pound-for-pound 
basis, calomel and corrosive sublimate may compare unfavorably in price with the 
commercial preparations containing relatively small amounts of mercury. Since 
their fungicidal value in turf maintenance, however, is determined by their mer­
cury content, they should be compared on the basis of cost per unit of mercury 
applied. Compared on this basis, it will be found that in most cases the inor­
ganic salts such as calomel and corrosive sublimate represent the best buy.

May 1940

The accompanying chart shows fluctuations in the price of mercury 

which have occurred during the last 35 years. The figures represented have 
been taken from New York quotations of the cost per flask of 76 pounds. The 
peaks in 1916 and 1918 reflect the increased demand for mercury due to its war 
use chiefly in the manufacture of detonators for explosives, together with the 
difficulty in importing our normal amounts of mercury from Europe. The peak in 
the years 1926-1929 reflect the world-wide increase in consumption of quicksil­
ver during the period of economic expansion prior to the depression in the fall 
of 1929. During that time new uses were found for it, particularly in the elec­
trical field.

The principal quicksilver sources in the world are the Almaden mine in 

Spain and the mines in Tuscany and Idria which are both in the hands of Italy. 
The reserves in the United States are not great and would be exhaustible in meas­
urably short periods if continued production were pressed. Although the ores in 
this country contain at best only 6 pounds of mercury to the ton, they are present 
in sufficient quantities so that 25,000 to 35,000 flasks (our yearly consumption) 
could be produced at a cost of $90 to $100 a flask, but any additional amount 
could be produced only at a higher price. It has been reliably estimated that 
70$ of our annual requirement could be furnished profitably from Arkansas re­
sources alone at $125.00 a flask, and these deposits are not ordinarily worked.

Therefore, it is only following peaks in prices that the American mines 

are reopened and new ones started. At present, domestic mines are producing larger 
quantities than were anticipated by authorities, and the price has eased. Figures 
for 1939 and 1940 show a sudden rise from an average price of $84.41 in August, 1939, 
to $140.00 in September and $183.00 at one time in March, 1940. The average price in 
April, 1940, however, was $173.54 as compared with the average March figure of $180.92.
It would not be wise, therefore, for clubs to set aside reserves of mercury 

fungicides at this time. Clubs that want to reduce the cost of turf disease control 
may well consider reducing the rates of application of calomel and corrosive subli­
mate which will accomplish wiser economy than shifting to lower grade mercury prepara­
tions. Also, some economy can be effected by treating the grass only as the presence 
of disease necessitates treatment rather than using preventive treatments as a reg­
ular practice.

May 1940