12 BULLETIN 1178, U. S. DEPARTMENT OF AGRICULTURE. 
Many times more mites appeared where copper sprays had been 
used than where sulphur sprays had been applied, and the mites 
were present in large numbers as early as May 14, especially on the 
unsprayed trees and on the plats sprayed with copper compounds. 
This can be accounted for on the supposition that the copper sprays 
inhibit the action of fungi which presumably attack 6 the rust mites. 
Although the mites were many times more abundant they were 
easily controlled by a single spraying with lime-sulphur solution 
applied on June 8. Up to this time the rust mites had caused little 
or no russeting of the fruit. 
The results presented in Table 3 are in keeping with those obtained 
during the past four years and in accordance also with observations 
made annually since 1914. 
1919 TREATMENTS. 
Similar results were noted in grove B, Winter Park, Fla., in 1919 
following one application on March 19, of essentially the same 
materials that were used the preceding year for scab control. Again 
citrus scab did not develop, nor was spray-burn observed. On 
August 21, 1919, there were many times more scales on the plats 
treated with simple Bordeaux mixture and Bordeaux-oil emulsion 
(one-half of 1 per cent of oil) than on any of the other plats. This 
rapid increase of scale insects was due to the omission of an oil spray 
in late June or early July, the most effective time for controlling scale 
insects during the summer months. 
On May 26 practically no rust mites were on the plats sprayed 
with any of the different forms of sulphur. In March they were 
much more abundant on the plats sprayed with Bordeaux mixture 
plus one-half of 1 per cent of oil as emulsion. On August 21 all the 
iruit on the sulphur plats remained bright, while the fruit on the 
Bordeaux-oil emulsion plat was very badly blemished by rust mites. 
Millions of mites were or had been present, as was evidenced by the 
number of dead bodies. This indicates that the fungus which pre- 
sumably kills rust mites had acted in the usual way, except that 
following the use of Bordeaux mixture it became effective very much 
later. On the unsprayed check plats the fruit was reasonably bright, 
but the percentage of first-grade fruit was much less than on the plats 
sprayed with sulphur. 
1920 TREATMENTS. 
Grove B, Winter Park, Fla., received one application of 3-3-50 
Bordeaux mixture plus 1 per cent of oil on May 4 to 7, 1920, for the 
control of melanose, with good results. On July 27 the young 
stages of the purple scale were present in great abundance, but little 
or no damage had been done up to this time. A spraying of 1 per 
cent of oil was given during the first week in August, which controlled 
the scale. 
e While definite proof that living rust mites are attacked by fungi has not been established, their change 
in color accompanied by sluggishness and herding prior to their sudden and enormously rapid dying early 
in the rainy season each year, the presence of fungal filaments within and sometimes protruding from their 
dead bodies, and the presence of more living rust mites on trees sprayed with copper compounds than on 
unsprayed trees are strong circumstantial evidences that living rust mites are attacked and killed by mi- 
croorganisms. 
