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February, 1910 



THE CANADIAN HORTICULTURIST 



39 



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Lime-Sulphur vs. Bordeaux 



(Continued from page 1) 

 Hme-6ulphur, especially commercial lime- 

 sulphur, can control apple scab in a very 

 satisfactory way, in fact just about as well 

 as Bordeaux. 



One point, however, has scarcely been 

 suflBciently well tested yet, viz., whether or 

 not as good results can be secured in wet 

 seasons. The last two summers have been 

 dry and have given the wash a good chance. 

 It is almost certain that a soluble substance 

 like commercial lime-sulphur would wash off 

 more rapidly than Bordeaux. If so, its 

 efficiency would be lessened unless an ex- 

 tra application were made. 



PE.4R SCAB 



On pear scab I have not got definite 

 data from any experiments except my own. 

 In the college orchard at Guelph there are 

 six or seven Flemish Beauty trees near 

 each other in three rows. Two trees in 

 the middle row were chosen. The fruit 

 and leaves of these were both very scabby 

 last jear. They were sprayed this summer 

 at the proper dates mentioned above with 

 Vanco lime-sulphur. The first application 

 was of the strength one to nine, the second 

 one to twenty-five, but as this burned the 

 *oliage considerably the other two were each 

 made one to fifty. In September, when 

 picked, the pears were absolutely free from 

 scab as were also the leaves. All the sur- 

 rounding trees which had received three ap- 

 plications of Bordeaux had considerable 

 scab on both the fruit and leaves. Probab- 

 ly if they had got the first application (the 

 one omitted) they would also have been 

 quite clean. However, the experiment 

 showed clearly that commercial lime-sulphur 

 would control pear scab even on Flemish 

 Beauty trees. 



LEAF SPOT 



As for leaf spot, Dr. Brooks has been 

 making a close study of the cause and rem- 

 edy for this disease. He finds that the 

 regular sprayings with either Bordeaux or 

 lime-sulphur will control it quite satisfac- 

 torily. This is valuable information be- 

 cause Professor Scott and Dr. Brooks have 

 both demonstrated that the disease which 

 causes most of these small round spots on 

 the leaves is also the cause of the back 

 rot caijker, and so a wash that will control 

 it in one form will also control it in any 

 other. The leaf spot seldom does much 

 damage to the leaves but its prevalence will 

 help to spread the cankers which are very 

 serious and require special care. There- 

 fore, its control is of importance. 



CANKERS 



There is not time here to discuss the prop- 

 er method of treatment for cankers but as 



already said "the first spraying must be in 

 the spring before the buds burst as the 

 spores spread very early and must not get 

 a chance to germinate. Lime-sulphur of 

 the regular home-boiled type has been well 

 tested this year for the spring application 

 and those who have used it think it vastly 

 superior as a spring treatment to Bordeaux. 

 The summer applications, as said above, 

 should be the same as for apple scab, and 

 either Bordpaiix or lime-sulphur, prefer- 

 ably the commercial form, may be used. 

 As the cankers occur on the trunks and 

 branches these will require to be very care- 

 fully sprayed in districts where cankers 

 abound. Badly infested orchards treated 

 in this way this year (1909) show no new 

 infections and a great improvement in the 

 health of the trees. 



BALDWIN SPOT 



Tests made by Brooks showed that Bald- 

 win spot could also be controlled by these 

 forms of lime-sulphur or by Bordeaux if 

 applied at the proper dates mentioned. 



The Use of Bordeaux Mixture 



Some important things about the use of 

 Bordeaux mixture have been determined 

 through experiments conducted by the Il- 

 linois Agricultural Experiment Station and 

 recorded in bulletin No. 135. A few of them 

 are : 



1. Injury to foliage of apple trees follow- 

 ing application of Bordeaux mixture is of 

 common occurrence. Much of the injury re- 

 ported or observed is preventable. The prin- 

 cipal sources of injury as determined by ob- 

 servation are: — (1) Use of impure or im- 

 proper materials. (2) Carelessness in mak- 

 ing the mixtures. (3) Improper and ineffec- 

 tive application. 



The first two of these sources of difficulty 

 can be entirely eliminated and the third 

 greatly mitigated by reasonable attention 

 and supervision. Formulas must be respect- 

 ed and small details of practice must receive 

 attention in order to attain best results. But 

 when all precautions have been taken injury 

 sometimes results. These non-preventable in- 

 juries are associated with unfortunate weath- 

 er conditions and particularly with the ac- 

 tion of rain and dew. 



2. The adhesiveness of Bordeaux mixture 

 depends very much upon the manner of 

 making and upon the character of the lime 

 used. Variation in the proi^ortions of cop- 

 per sulphate and lime beyond certain well- 

 defined limits decreases adhesiveness. With 

 lime of good quality a close approximation 

 of equal parts of copper sulphate and lime 

 gives greatest adhesiveness. There is decided 

 advantage in the maintenance of an excess 

 of lime upon the foliage, but this must be 



accomplished by subsequent applications and 

 not by increasing the amount in the original 

 mixture. 



3. No definite experiments regarding the 

 accumulation of copper in the soil under 

 sprayed trees have been conducted, but from 

 results reported of experiments of others it 

 does not appear that there is danger from 

 this source. There is no evidence at hand 

 that in any way associates browning or yel- 

 lowing of foliage with copper in the soil. 



4. The two classes of leaf injury considered 

 are, "brown-spotting" and "yellowing." 

 Brown-spotting is the more common injury. 

 Yellowing, when it appears in epidemic form 

 is the more serious of the two because affect- 

 ed leaves are entirely destroyed. Not all 

 brown-spotting is due to spraying. Other 

 causes are, frosts, winds accompanying cold 

 spring storms, fungi and insects. Leaf injur- 

 ies are most common and most serious in 

 neglected orchards. 



5. The ideal spray compound that is per- 

 fectly effective and at the same time per- 

 fectly harmless on all occasions and undei 

 all conditions has not yet been discovered. 

 Bordeaux mixture most nearly approximates 

 the ideal, but its harmlessness can not be 

 absolutely depended upon. 



6. Injuries to foliage do sometimes follow 

 applications of Bordeaux mixture and ap- 

 pear to be unavoidable. There are differ- 

 ences of opinion as to the exact manner in 

 which injuries are inflicted. 



7. The value of Bordeaux mixture as a 

 fungicide depends upon the contained cop- 

 per. The action is preventive and not cura- 

 tive. It follows that early application with 

 the one aim of defence gives infinitely bet- 

 ter results than later application intended 

 to check ravages already begun. 



8. The causes of yellowing of leaves of ap- 

 ple trees are obscure and not well under- 

 stood. From observations extending over five 

 seasons it seems certain that there are sever- 

 al causes which may operate singly, or to- 

 gether. Recurrent epidemics of yellowing ap- 

 pear to have no direct relation to wet or 

 dry periods, or to other weather conditions. 

 The experiments made do not establish any 

 direct and positive connection between 

 sprayincr with well-made Bordeaux mixture 

 and yellowing of leaves, but do show tha* 

 improperly made mixtures may cause yellow- 

 ing and that yellowing results from use of 

 simple solutions of copper sulphate. 



9. Health V bark of apple trees is imperm- 

 eable to Bordeaux mixture and solutions of 

 Conner sulnbate. Conper sulphate solutions 

 are absorbed through wounds and promptly 

 kill the leaves which then become brown 

 Numerous exnerimonts in which copper siil 

 phate and solutions were injected through 

 roots and through holes bored in trunks of 



I 



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