438 



Insect, Fungus, and other Pests. [sept., 



in spring when the buds are opening out and the mites are 

 exposed would probably account for many of the mites. A 

 spray suggested is composed of 2' lb. of sulphur, 25 lb. of soft 

 soap, and 50 gallons of water ; or the lime and sulphur treat- 

 ment recommended in the revised Leaflet No. 1 against the 

 black currant mite could be tried if practicable. The mite 

 has recently been found infesting the fruit and causing it to 

 fall prematurely ; attacked fruit should be gathered and burnt. 

 The pest is believed to spread very slowly, but one of the trees 

 at Hunstanton (a " Marie Louise "), which bore an excellent 

 crop in 1906, and then appeared to be unaffected, was observed 

 to be going wrong just as the fruit was setting in 1907, and all 

 the fruits but one dropped off. This has again occurred in the 

 present season. A tree of the same age and variety has never 

 borne blossoms, and this tree seemed almost untouched by the 

 mite in the spring of 1908, but by the middle of August appeared 

 to be nearly as bad as its neighbour side by side with it. 



Oats from Newcastle-on-Tyne were badly infested with eel- 

 worms, Tylenchus devastatrix (Leaflet No. 46 and Journal, 

 July, 1907, p. 224) ,; specimens of limes from York and Bos- 

 combe were attacked by gall mites (see Journal, July, 1908, 

 p. 277) ; gooseberries from Stockbridge, West Wickham (Kent) 

 and Southampton with Red Spiders (Leaflet No. 41) ; and ivy 

 from Oakham with the Red Spider of the ivy : this pest may 

 be very destructive. 



Fungi. — Damping off of Seedlings. — An inquiry as to the 

 damping off of seedlings was received from Thornton Heath, 

 (Croydon). The term "damping off" is applied to a disease 

 of seedlings, characterised by the falling over and dying of the 

 plantlets, due to the destruction of the fundamental tissue 

 of the stem just above ground by a fungus called Pythium de 

 Baryanum: Seedlings of cruciferous plants are more especially 

 attacked, but the fungus also attacks maize, millet, clover, 

 mangold and cucumber. Conidia, sporangia and sexually 

 produced oospores are formed by the fungus, but never in the 

 tissues of the hosts, always on its surface, or on the adjoining soil, 

 if sufficiently wet. . 



The conidia form one or two germ tubes almost immediately 

 after they are mature, or, under certain circumstances, after 

 a longer or shorter period of time, extending even to several 



