394 
Journal of Agricultural Research 
Vol. VIII, No. to 
Apricot trees are also very badly affected with symptoms almost iden¬ 
tical with those of the vine. Other trees, such as peach, walnut, almond, 
fig, and umbrella trees, show similar symptoms; but the resemblance to 
the trouble of the vine is less marked than in the cases of poplar and 
apricot. The symptoms have not been noted in any annual plant, even 
in the worst affected spots. 
COMPARISON WITH OTHER VINE DISEASES 
The symptoms distinguish little-leaf clearly from any other disease of 
the vine in California. To two European diseases, however, it shows a 
strong resemblance. These are “mal nero” and u court none” 
From the former it seems sufficiently distinguished by the different 
discoloration of the leaves. The u mal nero ” moreover, is infectious 
and is not confined to special soils. The name u court noue” meaning 
short-noded, indicates one of the most characteristic symptoms of little- 
leaf. It appears to be applied, however, to several distinct diseases. 
One of these has been shown to be due to a minute arachnid attacking 
the leaves. Others have been traced to winter frosts and bacterial 
infections in the old wood. Others are unexplained and may be iden¬ 
tical with our little-leaf. 
CONTROE EXPERIMENTS 
To seek to control a disease whose cause is unknown is to work in the 
dark. The need of a remedy, however, is so pressing that a considerable 
amount of work has been done in the hope of finding one. 
INSECTICIDES AND FUNGICIDES 
Affected vines were treated with various insecticides and fungicides 
on the supposition that the trouble might be due to some unperceived 
animal or vegetable parasite. 
Vines were sprayed at the swelling of the buds, when the shoots were 
6 inches long, and on the appearance of symptoms, with “Rex” and 
nicotine and with “Killthrips.” No results were noticed. 
Other vines were sprayed with Bordeaux mixture, iron sulphate, and 
dilute sulphuric acid in various combinations and at various times, but 
without any very noticeable results. Spraying in June with Bordeaux 
mixture produced some slight improvement for a few weeks, but later 
the treated vines were no better, if not worse, than the untreated. Other 
sprays had no noticeable effect. 
Swabbing the vines when dormant with 5 and 10 per cent solutions of 
copper sulphate had no effect. Swabbing the pruning wounds with 
0.5 and 0.1 per cent solutions of mercuric chlorid in winter resulted in 
the improvement of the vines early in the season, but later these vines 
looked worse than the untreated. 
