CERTAIN INSECT AND FUNGOUS PESTS. 



416 



specimens of the " parsley-worm," which is the larva of 

 the gay asterias butterfly [Papilio astcrias), and feeds 

 on the leaves of parsley, parsnip, carrot, dill, etc., as 

 well as celery. This parsley-worm is a handsome green 

 and yellowish fellow, but disagreeable, with a disgusting 



Fig. I.— Portion of Leaf Affected with Celery- 

 Blight (Cercoipora Apii, Fr.). 



odor. We have never seen either of these enemies 

 numerous enough to require the use of spraying mixtures, 

 such as buhach in water, or the kerosene emulsion, both 

 of which would probably be effective in an emergency. 

 The worms are easily discovered on the foliage, and in 

 ordinary cases may be disposed of by hand-picking. 



Hardly more serious, in ordinary cases, than the in- 

 jury resulting from caterpillar attacks, is that done to the 

 stalks underground by various grubs, larvae, beetles and 

 worms. Heavy applications of lime or kainit to the soil, 

 either in solution or dry, are likely to give relief from 

 these pests. Celery is not injured by such applications. 



FUNGOUS DISEASES OF CELERY. 



The celery-grower often sorely taxes his invention for 

 methods of saving his crops from blight or rust. This 

 is caused by a fungus known to scientists as Cercospora 

 apii (Fries), and ordinarily called celery leaf-blight, or 

 sun-scald. Hot, dry soil and seasons favor its develop- 

 ment. About midsummer, usually, we notice the ap- 

 pearance of small yellowish spots upon the outer leaves. 

 Later these turn yellow, then brown, and finally die. 

 If the plants survive until the cooler, moister weather of 

 autumn, they sometimes outgrow the disease ; but 

 usually the blight continues to spread, and often de- 

 velops on the plants even after they are stored for winter. 



The life-history of the celery-blight fungus is not yet 

 fully known, and preventive treatment has by no means 

 passed its experimental stage. Frequent sprayings with 

 a solution of potassium sulphide, one-half ounce to the 

 gallon of water, and with the Bordeaux mixture, have 

 been tried with varying success. Sometimes it has 

 seemed to us that the treatment in a measure prevented 

 the disease or its spread ; at other times the attacks con- 

 tinued in spite of all efforts. Further tests, perhaps 

 with other fungicides, will be needed. 



More promising for the present, as a preventive treat- 

 ment, is the careful selection of moist, cool soil, and 

 slight shading of the plants during hot, dry weather. 

 For this purpose the grower might adopt the system of 

 close planting, or planting in beds, as practiced at the 

 south, and shading by means of slatted frames. All dis- 

 eased leaves should be carefully gathered up and de- 

 stroyed. Some interesting notes on celery diseases are 

 quoted below from Professor Byron D. Halsted ; 



' ' The true celery-blight, or ' ' rust " as it is sometimes 

 called, is due to a fungus bearing the name Cercospora 

 apii, Fr It has long been known in this country and 

 is prominent among our destructive fungi. The appear- 

 ance of a leaflet of celery attacked by the blight is shown 

 in figure i. Experiments made at the station grounds 

 demonstrate beyond question that the blight can be 

 checked by spraying with the ammoniacal carbonate of 

 copper, even after the fungus has become well estab- 

 lished upon the plants, and that this treatment may 

 make all the difference between a fair crop and one that 

 is too poor to harvest for market. 



' ' Treatment should begin early. Very likely the period 

 of greatest susceptibility to the spores of the blight is 

 while the seedling is quite small. At this time and be- 

 fore the plants are set in the field the spraying could be 

 done quickly and effectively. It is even possible that 

 there may be a gain in beginning with the seed itself and 

 soaking it in a fungicide of proper strength before sow- 

 ing. It is also possible that some other compound than 

 the one used in these experiments will prove more ef- 

 fective, such as the sulphide of potassium. 



"Another celery disease is the celery leaf -spot (Phyl- 

 losticta Apii, Hals.). There will be no trouble in distin- 



FiG. 2.— Portion of Leaf Affected with Celery- 

 Blight {Septoria Petroselini var. Apii, B. & C. 



guishing between the two diseases even when they grow 

 upon the same leaf. The phyllosticta differs in the na- 

 ture of the spot, which begins as a dull-brown patch, 

 never becoming of the light ashy color so characteristic 

 of the cercospora in one of its stages. In the phyllosticta 



