12 



SCIENTIFIC AGRICULTURE 



September. 1921 



On the fruit the dust causes a certain 

 amount of russetting similar in nature to 

 that produced by a Bordeaux spray. Tliis 

 russetting, however, is not as s'^rious as 

 that produced by the spray, due in part, 

 in all probability, to the larger excess of 

 lime present. Also this russetting is almost 

 all caused by the application of dust at 

 the period immediately following the fall- 

 ing of the blossoms, as is the case with 

 Bordeaux spray. The russetting is in no 

 case serious and is reduced to a negligible 

 quantity by the substitution of the sulphur 

 for thi's one application. The foregoing 

 table shows the percentage of russetting 

 produced on Wagener apples by applica- 

 tions of various dusts and sprays at differ- 

 ent periods. 



The last spray combination on the table, 

 giving 10.3^7c of russetted apples, is from 

 the 1919 Nova Scotia Spray Calendar and 

 is in general and very satisfactory use. So 

 it is obvious that four applications of dust 

 would be expected to give slightly more 

 russetting than the spray calendar, and 

 that the substitution of sulphur dust for 

 the calyx application would give about 

 half the russetting of that produced by 

 following the Spray Calendar. 

 Control of Insects and Fung:! by Means of 

 Dusts containing Copper and 

 Arsenic. 



The cumulative evidence to be gathered 

 from the observation of hundreds of 



orchards treated with various materials, 

 is more impressive to the observer than 

 several experimental orchards. A survey 

 of the Annapolis Valley led to the con- 

 clusion that for 1920 the copper-arsenic 

 dust of 31/2 - 11/4 formula was the equal 

 of Bordeaux spray in fungus control but 

 slightly inferior in insect control. In 

 that particular year both seemed some- 

 what superior to 90-10 sulphur-leatl 

 arsenate dust. Areas treated with any of 

 the three materials were much superior 

 to areas which had received no treatment. 



During the past several years in the 

 cour.s.e of these investigations, the writers 

 have used several hundred small plots of 

 two trees or so to a plot. On all these 

 areas where the per cent of ars.?inic in the 

 dust was 1% or more the control of biting 

 insects was good. It is to be regretted 

 that no opportunity has been found for 

 testing the material in the control of an 

 epidemic outbreak of codling moth. This 

 insect, never very prevalent in Nova 

 Scotia, has lately been particularly coii- 

 spicuous by its absence. 



The chii^f experimental area for these 

 materials used by the writers has consist- 

 ed, for the past few years, of a fifteen 

 acre block of orchard of the Gravenstein 

 varicfty, situated in Berwick and owned 

 by Mr. S. B. Chute. Unfortunately, foi 

 experimental purposes, insect pests have 

 not been numerous in this orchard but 



Table 1. 

 Material 



Results from S. B. Chute's Orchard, 



No. of 

 apples 

 counted 



Clean Scab 



Unsprayed . . 5,500 

 Sprayed as per 

 1919 Nova Scotia 

 Spray Calendar 5,500 



Dusted with 

 3-1 copper 



Arsenic dust 5,500 

 Dusted with 

 90-10 sulphur- 

 lead arsenate 



dust 5,500 



Dusted with 

 commercial 

 Bordeaux . . 5,r)00 



p.c. 

 0.19 



77.89 



73.49 



85.29 



67.82 



p.c. 



98.81 



Russ- 

 etted 

 p.c. 

 0.16 



Bud- 

 moth 



p.c. 



2.98 



Cod- 

 ling 

 moth 



p.c. 



0.11 



1919. 

 Green 



fruit Tussock 

 worm moth 



21.14 2.16 1.58 0.16 



20.45 0.23 



11.4 



:7.9 



2.09 



3.32 



2.32 



1.96 



0.0- 



0.01 



p.c. 

 3.12 



0.89 



2.14 



1.9 



2.51 



p.c. 

 0.78 



0.07 



0.27 



0.03 



