PESTS OF GARDEN VEGETABLES. 



823 



The only application which has proved effectual is that of " flowers 

 of sulphur," as in this case the fungus is an epiphyte, and is open to 

 similar treatment to that for the vine mildew. 



Said to be common throughout the world. 



Sacc. Syll. iv. 189. 



Cucumber and Melon Eot Mould. 

 Plasmopara cubensis (B. & C). 



This rot mould was first discovered in Cuba, from whence it after- 

 wards spread, until it was found on leaves of Cucurbita and Cucumis in 

 Japan. More recently it became known in the United States, and 

 afterwards in England. 



It forms a delicate white mould on the under surface of the leaves. 

 The erect branches are forked on the upper portion, with the ultimate 

 branches straight, and not hooked as in some species. The conidia are 

 oblong-obtuse at the ends (25 /x long). 



It has been recommended to spray the under surface of the leaves 

 with dilute Bordeaux Mixture, taking care that the under surface is 

 reached and wetted. 



Berk, and Curt. Cuban Fungi, No. 646 ; Sacc. Syll. vii. 872 ; Mass. 

 PL Dis. 80. 



Melon Spot Mould. 

 Cercospora Melonis (Cooke), PI. VIII. fig. 129. 



This disease made its first appearance on the leaves of Melons in 

 1896, and since that time it has been even more troublesome with 

 Cucumbers, and may now be looked upon as a constant danger. 



The leaves are spotted sometimes with rather small orbicular spots 

 with a definite margin, and of the usual bleached dirty-white colour. 

 At other times the spots are larger, one inch in diameter, and of a smoky- 

 grey colour. The mould appears on these spots, but hardly distinguish- 

 able to the naked eye — save to slightly darken the centre cf the spots. 



The erect threads are few and slender (200 /x long) and of a decided 

 olive colour. The conidia are robust for the genus to which they belong, 

 either cylindrical, or slightly attenuated upwards, and divided by seven 

 or more transverse septa (80-120 x 7 ft) and a little curved, but scarcely 

 at all coloured. 



Spraying with dilute Bordeaux Mixture will probably assist, but 

 infected leaves should be picked off and burnt. 

 Gard. Chron. Sept. 5, 1896, p. 271. 



A Musk Melon disease is attributed to a black mould (Alternaria) in 

 N. America ; see Journ. B.H.S. 1901, xxvi. p. 563. 



We know nothing whatever of the smut on Cucumber roots described 

 under the name of Ustilago Cucumis in Proc. Boy. Soc. Ed. xv. 1887, 

 p. 403. 



