ON PESTS GENERALLY. 



II03 



lor which he was indebted to the Journal of the Pharmaceutical 

 Society. Cut some long strips of brown-paper, bend them over 

 like a conduplicate leaf, and smear on one side a mixture of 

 treacle, foot-sugar, and beer. They will crowd to this feast, when 

 the papers may be lifted and shaken over a vessel of boiling 

 water. Small flower-pots similarly treated on the inside will 

 prove equally as attractive. 



Vegetable Foes. 



Compared with Animal Pests those belonging to the Vegetable 

 group are numerically insignificant, yet they are even more 

 insidious, as well as more difficult to cope with because, as 

 regards their life-histories, so much remains to be perfected. 

 Vegetable pathology, though no new science, is yet in its infancy. 

 More than half a century ago there were earnest workers in the 

 field, as evidenced by the more stable literature of the day, as 

 well as by the record in the more ephemeral gardening press. 

 Until the last twenty years, however — at any rate, so far as this 

 country is concerned — there have been few who have attempted 

 to follow in the lead that Berkeley established in the case of 

 parasitic fungi. These, of all Vegetable Pests, are the most com- 

 plicated to the average gardener, as they are also the most 

 numerous, and the most disastrous and far-reaching in their 

 effects. As a proof of this latter, one has but to instance the 

 Sleeping Disease of Tomatoes {Fusarium lycopersici), of which 

 so much has lately been heard, both in Guernsey and in this 

 country, where a whole season's crop may have to be sacrificed 

 owing to the seed having been obtained from a diseased 

 source. 



To many gardeners the methods by which fungoid diseases 

 are reproduced are absolutely unknown, and such visitations as 

 -Mildew of various kinds are attributed to chance, or oftener to 

 weather influences. Then there is a still larger section who 

 regard such diseases as "not proven," or their injurious properties 

 as having been exaggerated. Even to-day there are thousands 

 .who believe that the disease of Apple and other trees, popularly 

 called Canker, may be remedied by improving the soil, or by 

 keeping the roots out of the sub-soil. That such treatment will 

 benefit trees under certain conditions there cannot be a shadow 

 of a doubt, but that it will cure Canker proper is incorrect. 

 Canker is due to the attack of a specific fungus, usually 

 Nectria ditissijiia, which gains access by means of a wound. 

 Once there the disease rapidly spreads, and when ready to 

 produce its fruits, or spores, it causes the bark to crack ; or 

 again, to be distorted in the way shown at Fig. 718, disclosing 

 the affected parts. In spring, if such trees be examined even 

 without the aid of a glass, the deep red perithecia (spore-bearing 

 cases) will be detected. 



