The National Nurseryman. 
FOR GROWERS AND DEALERS IN NURSERY STOCK. 
Copyright, 1897, by the Nationil Nurseryman Publishing Co. 
VoL. V. 
A SCALE FUNGUS. 
Particulars of Its Discovery by Professor 
P. H. Rolfs, of Florida —Now Being 
Tested In the North and East. 
Attention was called in the last issue of this journal to the 
discovery by Professor P. H, Rolfs, entomologist of the Florida 
Experiment Station, Lake City, Fla., of a fungus disease of 
the San Jose scale. Special interest is taken in anything which 
may prove destructive of so pernicious a pest. In response to 
an inquiry by the National Nurseryman, Professor Rolfs 
has kindly furnished the following detailed account of the dis¬ 
covery and application of this fungus : 
It is difficult and probably impossible to say just at what 
time the San Jose scale were introduced in Florida, but these 
insects were doubtless brought here from California on nursery 
stock. In several instances the introduction of this insect has 
been traced directly to that source. Such a misfortune could 
not now occur under the present horticultural laws of Califor¬ 
nia. It is certainly a credit to that state, as it would be to 
any other, to have such rigid laws regulating the introduction 
and dissemination of material so dangerous to the horticultural 
interest of the state, and at the same time to protect other 
states from receiving infested material from its own borders. 
The genial climate and long summers make the State of Cali¬ 
fornia an especially fine habitat for this insect. 
In Florida this insect flourishes and is disseminated very 
rapidly from February or March until about the first of July. 
About the latter date the summer rains commence. During 
this season myriads of young crawling San Jose scale are 
washed from the host plant down into the soil and destroyed. 
While it multiplies very rapidly and moves on to the newer 
growth of the trees, the rapid increase which took place during 
the months of May and June is now somewhat suspended ; 
though to the unskilled eye it appears that July and August 
are the months when the scale spreads the most rapidly. After 
the summer rains cease, during the months following Septem¬ 
ber, the wood and bark of the fruit trees harden so much that 
the young scale have greater difficulty in locating themselves. 
From the foregoing it will be seen that the scale insect in 
Florida has a chance to increase about as much in one season 
as during three in our Northern states. It has been observed 
repeatedly that a peach tree which was perfectly free from San 
Jose scale when planted into the infested orchard became so 
infested with San Jose scale before the end of the year that 
there was not a spot as large as a dime, excepting on the leaves, 
where none of the scale were present. It has been observed 
repeatedly that a few trees planted in an orchard could so in¬ 
fest it that only a small per cent, of the trees were alive at the 
end of three years when the orchard was treated in the normal 
way. 
f' 
No. 8. 
While working in orchards during the summer of 1895 I 
noticed what seemed to be a mortality among these insects. 
A careful search for the cause was instituted, but nothing 
could be discovered that gave definite information regarding 
the subject. During the summer of 1896 the search was re¬ 
newed. This time greater care was taken and more time used 
for careful observation. Several orchards that were badly in¬ 
fested with San Jose scale in 1894 were found to be free from 
this pest, but usually the orchard had been sprayed or other¬ 
wise treated. Finally an orchard was found which had not 
been treated, and yet was almost free from scale insects. It 
was in this instance where the fungus was found. Immedi¬ 
ately upon the discovery, specimens of diseased insects were 
transferred to an orchard about two miles away where the 
scale insects were flourishing and healthy. At the end of six 
weeks’time this mortality became noticeable among the insects 
of the orchard where the fungus had been introduced. 
Specimens of the fungus were taken to the Experiment Sta¬ 
tion laboratory and cultures begun with the view of propagat¬ 
ing it artificially. After many repeated trials it was finally 
discovered that stale bakers’ bread was the best medium at 
hand. It produced spores in unlimited quantities and in ex¬ 
cellent condition for artificial infection. 
The spores thus produced are short-lived, and must be ap¬ 
plied under favorable conditions. It is imperative that moist 
atmosphere must follow such an application for several hours. 
The natural time would be during an evening or night follow¬ 
ing an afternoon rain. Happily this condition may be artifi¬ 
cially brought about. The spores may be applied to the portion 
of the tree infested with this insect, and that portion of the 
tree then wrapped with wet burlap or other coarse cloth. 
The all-important point is to get the infection to take, for 
when a few insects are once diseased the fungus will produce 
spores in countless numbers, beside sending the mycelium from 
one insect to the adjoining one. Thus the infection may be 
carried on until three-fourths of the insects of the tree are dead 
before the most practiced eye would discover the fact. It is 
only under certain conditions that the fungus produces the 
orange-colored protuberance that led to its discovery, the 
greater amount of good being done by invisible spores and the 
mycelium. This may be discovered, however, by the use of a 
compound microscope. In summing up it may be said : 
This fungus is doubtless a native to Florida, but it has also 
been discovered in several other states and at least three 
continents. It has been known in Europe for more than thirty 
years. It may be transferred to trees affected with San Jose 
scale and the disease produced among these. Material may 
be produced in the laboratory at slight expense. The labora¬ 
tory-grown material may be applied successfully by fruit¬ 
growers. This fungus cleared the orchards more effectually 
of San Jose scale than could have been done by insecticides. 
It is now being tested by the best entomologists in the North 
and East, who will report on the subject in proper time. 
ROCHESTER, N. Y., SEPTEMBER. 1897. 
