1922.] Anthracnose of the Cucumber under Glass. 561 



any ap})reciable damage. If the fungus is allowed to (jet a 

 strong hold upon the leaf-stalk or stem tissues, it is increasingly 

 difficult permanently to check the disease. Its spread may be 

 stopped for a time, but as only the spores and spore-bearing 

 parts of the fungus on the outside of the plant are killed, the 

 fungus within the stem grows out in time and produces masses of 

 spores, which are rapidly carried about the house and the dis- 

 ease again appears. In these cases it is advisable to remove the 

 diseased individuals and replant the house after thoroughly 

 cleaning it. 



The cleansing may be effected by means of the cresylic acid 

 emulsion described, after which planting must be deferred for 

 a fortnight; or else by a solution of liver of sulphur at the rate 

 of 6 lb. in 100 gallons of water, or lime-sulphur at the rate of 

 8 pints per 100 gallons. When liver of sulphur or lime-sulphur 

 is used, the house may be replanted in 24 hours. 



(c) Dusting. — Dusting with sulphur powders has been exten- 

 sively tested, but while it checks the rapid spread of the fungus, 

 a complete control has never been observed. 



{(b Cultural Methods. — Much can be done to preve'-it and con- 

 trol the disease by providing the best cultural conditions for the 

 plants. The disease assumes its worst form and spreads most 

 rapidly, when the atmosphere of the houses is badly ventilated 

 and saturated with moisture, and also when there is a marked 

 difference between the day and night temperatures in the houses. 

 The conditions which best enable the plants to resist the disease 

 may be summarised as follows : — 



Plants should be grown steadily from the beginning, without 

 any attempt at forcing, and a little air should be given when- 

 ever outside conditions will allow. The atmosphere of the houses 

 should never be stagnant or saturated with moisture for long 

 periods and efficient circulation of air should be encouraged by 

 suitable ventilation. The beds should never be cold or sour, 

 and careful attention should be paid to the mair.tei.ance of 

 constant day and night temperatures. 



Conclusions. — (1) C. oUgochaetum, Cav., which causes 

 Anthracnose of the cucumber, carries on a saprophytic existence 

 in rotten woodwork, timber, paper, etc., in the glasshouses, and 

 thus tides over the winter period. 



(2) Straw manure from towns constitutes an important source 

 of infection. 



(3) Infected houses may be cleansed by spraying the interior 

 woodwork during the winter with emulsified cresylic acid. 



f; 



