Jano 18, 1868. ] 



JOURNAL 01' UOIiTIOUIiTUlUS, AJfjp, COTTAGK GABDENEK 



4U 



SUGGESTIONS AS TO THE CAUSES AND 

 PREVENTION OP IJCHENS ON FRUIT TREES. 



OME time ago a correspondent called atten- 

 tion to what threatened to prove a serious 

 evil both to fruit and forest trees — namely, 

 thoir becoming covered with a lichen of a 

 light gi-ey colour. This, he stated, had been 

 much on the increase of late years, and fears 

 were entertained tliat the growth of young 

 trees would be completely arrested, and that 

 premature old age would set in ; he asked 

 what could be done to check tlie mischief, 

 and whether its increase had been noticed in otlior locali- 

 ties as well as tliat he wrote from. These and similar 

 qiiesiions are fitting subjects for inquiry in the pages of 

 this Journal, and as the evil exists to a serious extent 

 here (Kent), I venture to make some remarks on the causes 

 which appear to favour the growth of lichen, and to offer 

 a few COD jectui'es as to its prevention. 



The evil is not a new one, for moss-grown trees have 

 probably existed over since trees arrived at an advanced 

 age ; but it is quite possible that many trees now become 

 covered witli moss at an earlier age tlian in former years. 

 and that they are much ali'ected by it iu localities where 

 at one time it was comparatively rare. It is certain that \ 

 the moss interferes with the healthy action, and checks ' 

 the due development of the plant supporting it, while it no ! 

 doubt hastens the death of the more aged specimen ; still [ 

 its growth and progress seem to be dependant on causes ] 

 difficult to comprehend, as trees occupying widely diti'erent i 

 positions are often alike affected, so that some other cause , 

 than locality must be sought for. 



Happening to be travelling in the western part of Lan- 

 cashire lately, I bad an opportunity of looliing over some 

 orchards of Apple and other trees n.t<lift'«rent plsces, and 

 although the climate is proverbially moist, and few fields 

 or enclosures were witliout water in a ditch, stream, or 

 pond, the trees were comparatively free from moss or 

 lichen; while at a very short distance from the place 

 whence I write ti'ees of the same description are covered 

 witli it, althotigh water could only be obtained by (ligf»ing 

 down loo feet or more; and, the situation being elevated, 

 tlie air may also Ixs said to be dry, Now, liero is a strong 

 argnment against moisture being the canse ; but I feel 

 convinced as regards the .Lanca^liire. trees that, besides Jts 

 presence, another cause kept the parasite at hay, and 1 

 believe that the strong sea breeze had much fo do with its 

 absence. In tlie case of the correapondeift reffcrre<l to, I am 

 inclined to believe that the want of moisture, or at least of 

 a sufficient quantity of if. Caused his. trees to be so. over- 

 grown with lichen, and one of the most likely theories would 

 seem to be tha^ the sijiljand ,(^mate (for both may be in 

 fault), were not fayourahle. fp .the.' Apple growing wiih 

 sufficient vigour to resist the atlac'ks of lliis parasite; 

 or, shall we say that the climate fend other things fa- 

 voured it^ growth more than that of tl)e stock which sup- 

 ported; it; One or other of these causes must have, been 

 at work ; but let ns e:5aBli5.e fh^ mattfr stiU-fnrOi<*x*ii4; 



take a third place into consideration, and this is one where 

 the lichen was also absent, and in a position where the tw* 

 was in anything radier than a boallhy condition, but it 

 may, perhaps, give us some insitiht into the cau.^ns whieh" 

 encourage the production of lichen and moss on trees. 



Having an opportunity of looking at the cmdition of 

 some Apple and other fruit trees, as well as of forest trees 

 and shrubs growing in the suburbs of a large mannfactnr 

 ing city, I failed to discover a particle of moss, allbongt 

 I he trees and shrubs could not be called healthy, and, in 

 i'act, were encrusted in soot as thick, probably, as the bark' 

 that covered them. Here the case was plain enough, the 

 tree could drag on an existence in spite of the soot, but the 

 moss could not, the impurities of the atmosphere wc*e 

 fatal to it : hence its non-appearance. I will not say that- 

 its dirty substitute is not the worse evil of the two. 



Let us now examine the causes which contribute to tlie- 

 prodnction of lichen, and on considering the three cases 

 which I have given it would appear that a clear pnre- 

 atmosphere free from saline or smoky matters tends to 

 encourai;e it, and I am inclined to think that both an 

 excess and deficiency of moisture are also favourable to 

 it, I am not in a position to affirm this with certainty a» 

 regards living objects, but as to those which are not so, I 

 will observe that the p<irk here is surrounded by a close 

 oak paling about li feet high. The palings bcinsr cleft 

 and standing upright last a great many years, and I have' 

 often pointed them out to painters as a proof that theii- 

 so-called preservative mixtures failed to keep any descrip 

 tion of outside timber work so long as these slender strips 

 which had no such covering. The Silver Moss, as it is 

 commonly called, has more or less covered these (lalinge 

 jus', as it did the branches of Apple and other trees, and 

 on a portion of the fence which passes through some damp 

 clayey ground overluing by trees, the moss exists in great-er 

 abundance than where ilie fence is on liigh or open groundr 

 This may be easily accounted for. A stagnant atmosphere, 

 whether moistordry, is iu general favourable to the prowth 

 of lichens, hut more so when ihe air is moist; and this 

 leads me to think that the muss is as much indebted to the 

 atmosphere for an existence as to the bodv it is jrrowiug on 

 as in the case of the oak palings, which in some instances 

 are densely covered with a thick beard 1 ' inch Ion,?, the 

 support it can receive from Ibe wood must be very sniaU ; for 

 although the moss probably to some extent hastens ilie de- 

 cay of the oak, tliis la.sts so many years as to prove tbdt the 

 amount of its substance wliicli it Itas given to vej:elatjoij 

 must have been very small. I'ossiblvtha destriictioaof the 

 wood may have been counLorbjilanced in some degrrn by UtC 

 preservative effect which a clayey soil is said to hrtve on 

 Oak timber. Posts of it li^red in tbe pronnd are s*iid to 

 stand longer in a clayey soil ilntn in rt dry sandy or rjravellj 

 one. As palings densely covered witli this lirheti win 

 last a great many years, I imiigiiiG that the Jielimj is as 

 mneh indebted to the atmoapbcn; for its existence aft to the 

 wood on which it is growing, and tliat its pre,switte u,n Apple 

 trees is, after all, not s.i di'iriuifii'iil as nii)^ht.l,>e su|if«>8ed: 

 W* ought act, hotveyer. to be st).tit,lWd wjUi llus-t4'in»ioo, 

 fta theM'Oan 'Wdly be; a 4«ubt,ijiat.a di«."a)thjMreej«iilw«t 



U Smiooi oadw «a9Mqaa;..iiKauU9)<*yfk<ilXXai^'90ia> saiusgida': 



