310 



INJURIOUS INSECTS AND FUNGI. 



[Marcli 1895r 



Experiment Station, has just published a most elaborate bulletin 

 upon this cabbage-root maggot, and the results of a series of 

 experiments " with a view to finding some effective preventive 

 or destructive method of combating it." This pest was so trouble- 

 some in Long Island that many gardeners had given up trying to 

 grow early cauliflowers and cabbages solely on account of its 

 ravages. Some new and interesting discoveries in respect of this 

 insect have been made by Mr. Slingerland. Among these is the 

 fact that the cabbage-root maggot in the United States not only 

 feeds upon cabbages, cauliflowers, radishes, turnips, swedes, and 

 stocks {Matthiola), as in Europe, but it also feeds on the 

 common winter cress {Barharea vulgaris) and the hedge mustard 

 (Sisymhrium officinale). Mr. Slingerland has found the maggots 

 on the roots of these plants, and is of opinion that they 

 probably infest other cruciferous weeds. He writes : " If all 

 the cruciferous weeds could be exterminated and none of its 

 other cultivated food plants be grown unprotected near by, then 

 a few years of prevention with the cards would doubtless starve 

 out the pest in that locality." This " prevention with the cards " 

 means encircling each cabbage or cauliflower plant directly it is 

 transplanted with tarred paper collars resting close upon the 

 ground. These tarred cards, or paper collars, are cut with six 

 sides, and are about 3 inches long by 3 inches broad. A slit 

 runs to the centre, in which a " star-like cut " is made. To put 

 the card in place it is bent slightly, the slit is opened, and the 

 stem put in and slipped to the centre ; the card is spread down 

 flat, and the points left by the " star-like cut " are pressed around 

 the stem. The tarred paper prevents the flies from egg laying 

 on the stem. 



Spraying plants with carbolic acid emulsion appears to have 

 been efficacious in preventing egg laying. This is made with 

 1 lb. of soft-soap and a half gallon of crude carbolic acid mixed 

 with J gallon of water, and then diluted with from 50 to 75 

 parts of water. Mr. Slingerland says that spraying with a 

 stronger carbolic acid emulsion will, he believes, " kill eggs and 

 recently hatched maggots." 



Carbon bisulphide injected close to infested roots has proved 

 aLgreat value. - This is put -into the ground round the plants by 

 means of a clever instrument known as the McGowen injector, 

 very much less clumsy than the " Pal injector " used for injecting 

 carbon bisulphide in the French vineyards, though its principle 

 is similar. The reservoir of this will hold 2 quarts of the carbon 

 bisulphide, which is sufficient to treat about 500 cabbage plants. 

 The cost of the injector is from 12s. to 25s. Carbon bisulphide 

 costs about Qd. per lb. in America, and about a teaspoonful is 

 required for each plant, costing about ^d. Mr. Slingerland 

 believes " it is the best, cheapest, and most effectual and most 

 practicable method yet devised for fighting this pest on crops of 

 cabbages and cauhflowers ; on crops of radishes, turnips, or 

 onions it will probably be too expensive." 



