FLORIDA STATE HORTICULTURAL SOCIETY 
73 
21; 18.8% of the fruit on these trees were 
found to be affected with Black Spot and 
Blotch on August ist. 
Group 7 was sprayed twice during the 
season with 4-4-50 Bordeaux Mixture. 
The first application was made May 21 
and the second on June 22. Sixty per 
cent of the fruit on these trees were found 
to be badly affected with Black Spot and 
Blotch on August ist. 
Group 8 was sprayed only once during 
the season with 4-4-50 Bordeaux. This 
application was made on May 21. On 
August ist when the fruits were exam- 
ined, 97% were found to be affected with 
Black Spot and Blotch. 
Group 9 was not sprayed during the 
season and served as a check. The fruits 
were examined on August 1st and 84% 
were found to be affected with Black Spot 
and Blotch. Why the unsprayed trees 
should show less spotting than the trees 
in group 8, which was sprayed once, can 
probably be explained by the fact that two 
trees in this group showed a marked de¬ 
gree of resistance to these diseases. 
In summarizing the results it will be 
noted that sprayings made in April and 
May were more effective in reducing the 
amount of Black Spot and Blotch. 
Where the April spraying was omitted 
the disease showed an increase following 
two applications of Bordeaux Mixture. 
For the control of Black Spot and 
Blotch the bloom spray hardly seems nec¬ 
essary. It appears to me that these dis¬ 
eases can be controlled by two timely ap¬ 
plications of Bordeaux Mixture, or three 
at most. The first spraying need not be 
made until the fruit is well set, probably 
two or three weeks after the bloom has 
disappeared. A second spraying should 
follow three weeks to one month later 
and possibly a third spraying three weeks 
to one month after the second. I would 
advise the use of 4-4-50 Bordeaux Mix¬ 
ture which should be made of fresh stone 
lime rather than hydrated lime. 
The above experiment will bear repeat¬ 
ing and should be carried through a few 
more seasons before final conclusions 
might be drawn, but from the results ob¬ 
tained it seems to me that spotting of the 
Avocado fruit can be easily taken care of 
by timely and efficient sprayings. The 
lime sulphur solutions might work equal¬ 
ly as well as the Bordeaux Mixture and 
they should be tried out along the same 
lines. I can see no serious objection at 
the present time, however, to the use of 
Bordeaux on the Avocado tree. 
A similar spraying experiment for the 
control of Avocado Scab was carried 
along with the sprayings for Black Spot 
and Blotch. In each case the sprayings 
were made on the same dates and the 
same solutions were used. The scab 
spraying experiment, however, was con¬ 
ducted in a different grove. The trees 
were of the Trapp variety and were in 
their second or third year of bearing. 
Eight blocks of trees were set apart for 
this experiment. 
Block 1 of ten trees was sprayed once 
during the season. An application of 
3-3-50 Bordeaux was sprayed directly 
into the bloom on March 23. The fruits 
were examined on August ist and 25% 
of the fruit on these trees showed slight 
scab infections. 
