SUBSEQUENT CARE OF THE PLANT 167 



squnsh-buu: or stink-butr, ainl tin- Ifuf-lioppers). 

 We may classify injuiious insects apiiii, without 

 roftMvnco to- their mode of takiiiji: foo*!, iiit«» 

 those which live and feed on the outsid«' of tlx- 

 plant, and those which, as borers and apph'- 

 wornis, burrow and feed inside the tissue 



292. Of funufous pests, the farmer uiay lecotj- 

 nize two j^roups,— thos«« which live wholly on the 

 outside of the host (as the po\v(|fry mildfw ot' 

 the j^'ape, pea mildew), and thos«» which live 

 wholly or in part inside the tissues (as apple- 

 scab, black-knot, potato mildew). ^fost inju- 

 rious funiri are of the latter kind. Fungous 

 troubles are n«'arly always marked by <lclniitely 

 diseased spots on the leav«'s or twii^'s. 



293. Physi(^l<»«^ical or c»»nstitMtion;il troubles 

 are those winch affect the whole plant or an 

 entire leaf or branch, and the cause of which is 

 not appan^nt on the exterior. These troubles 

 may be due to j^erms or bacteria workinu: within 

 the tissues (as pear-blii,dit ) , or to some dilliculty 

 in the nutrition of the plant. Th«'S«' troubles 

 are generally not marked by <lciinitely disc»ased 

 spots or blemishes, but by tlie jifradinil dyin^ of 

 an entire leaf, branch or |ilant. 



36. The pfrirnlivis and trnwilies 



294. Keepinj; the plants vii^orous and healthy 

 IS tlie first step toward^; '* i.tr..! ,,f posts mim! 



