Page 20 



ature between Carpinteria and Santa 

 Ana, while not very great, accounts for 

 the difference in life history. 



Feeding Habits 



Many of the larva; that appear early 

 in the spring enter the nut at the calyx 

 end, but after the nuts attain some size 

 and are large enough to come into more 

 or less contact, protection is afforded 

 at this point, and for the remainder of 

 the season most larvae enter where two 

 nuts are in contact. The nuts that are 

 attacked early in the season, while they 

 are still immature, fall to the ground, 

 and these are not accounted for at har- 

 vest time. Up to the middle of July the 

 larvae as a rule bore directly toward the 

 center of the nut. Up to this time the 

 shell has not hardened to any extent. 

 From the middle of July on, however, 

 the shell is so hard that the larvae can 

 not make their way through the shell, 

 and the only place they can enter the 

 nut is through the suture at the base. 

 They may enter the husk where two 

 nuts are in contact as usual, but when 

 the shell is reached they bore along the 

 shell more or less at random. The ma- 

 jority of them sooner or later find the 

 suture, where they enter and feed on 

 the meat of the nut. Some that do not 

 find the suture may complete their de- 

 velopment in the husk of the nut alone. 



Control 



The control of the codling moth in 

 walnuts must necessarily follow in gen- 

 eral the methods that have been de- 

 termined upon, after extensive investi- 

 gation, in the case of the same insect 

 in the apple. There are certain differ- 

 ences and difficulties, however, in the 

 case of the walnut. The large size of 

 the walnut trees presents greater diffi- 

 culty in reaching all parts. There is 

 no calyx cup to fill, as in the apple, and 

 it is also necessary to get the poison 

 where two nuts are in contact. 



Banding 



Burlap bands placed around the tree 

 trunk serve as a place where larvae re- 

 pair to undergo pupation. While some 

 of the worms enter here, there is not a 

 sufficient number to afford satisfactory 

 commercial control. Since after the 

 first month or so the worms enter the 

 band almost continuously it is neces- 

 sary that the bands be removed and in- 

 sects beneath killed, in order for the 

 bands to be effective. To avoid the 

 trouble of attending to the bands every 

 couple of weeks the improved band, 

 which was first used by E. H. Siegler in 

 Colorado, was used. This consists of 

 the ordinary burlap band, over which 

 is placed twelve-mesh mosquito wire 

 netting. This sort of a band allows the 

 worms to enter through the meshes of 

 the screen when they go under the 

 burlap band to spin their cocoons as 

 usual, but when the moth emerges it is 

 unable to make its way out through the 

 screen through which the larva 

 entered. Hence such a band serves as a 

 permanent trap. While these bands 

 check a few of the insects there still 

 may be a heavy percentage of infesta- 

 tion on the same tree. 



BETTER FRUIT 



Spraying 

 Spraying is the method of control 

 generally relied upon for the codling 

 moth in the apple and it proved to be 

 satisfactory the past year in the control 

 of the same insect in the walnut. A 

 considerable amount of spray material 

 is necessary to cover a tree, and this 

 would seem to be a serious objection to 

 spraying. An average sized walnut tree 

 will require 25 gallons of spray to cover 

 it thoroughly. The largest trees may 

 require as much as 35 gallons. Good 

 sized apple trees may be covered with 

 eight or ten gallons, but the tree basis 

 is not the proper way to make the com- 

 parison. While the walnut tree re- 

 quires much more material there are 

 fewer trees to the acre, so that on an 

 acre basis there is not much difference 

 between the amount of material needed 

 for walnut and apple spraying. If a 

 walnut tree requires 25 gallons and 

 there are 20 trees to the acre, the 

 amount of spray material per acre will 

 be 500 gallons. If an apple tree re- 

 quires eight gallons of spray and there 

 are 60 trees to the acre the amount of 

 material per acre will be 480 gallons. 



Dusting 



A large acreage was dusted during the 

 past season (1919) for the codling moth, 

 that is, arsenate of lead was applied 

 dry rather than being mixed with water 

 and used as a liquid. The dry material 

 has been used with success in some sec- 

 tions on the apple. Dusting in the 

 Santa Ana and Carpinteria sections has 

 resulted in a considerable reduction of 

 wormy nuts. The chief objection dur- 

 ing the past year was due probably to 

 lack of thoroughness in covering the 

 tree. While the aphis is readily killed 

 by the dust, in the case of the codling 

 moth it is necessary to have the arseni- 

 cal on every nut on the tree for good 

 control. Another objection to the kind 

 of dust that was used last year was the 

 injury that resulted to the tree. The 

 walnut tree is very susceptible to in- 

 jury by spray materials, and hence only 

 the most neutral materials can be used 

 with safety. 



Fortunately the objection of injury 

 to the tree may be easily and completely 

 overcome by using basic or neutral ar- 

 senate of lead, rather than the standard 

 or acid arsenate of lead that was gener- 

 ally used during 1919. Where the writer 

 employed the liquid spray, basic arse- 

 nate of lead was used with no injury 

 whatever. Some of the second applica- 

 tions of dust also consisted of this mate- 

 rial and no injury was done. Basic 

 arsenate of lead is not as powerful a 

 poison as the acid arsenate, hence is 

 slower acting on the larvae. In the case 

 of the walnut, however, if the poison 

 kills the larvae eventually it would be 

 satisfactory, because a small burrow in 

 the husk alone will not affect the nut, 

 whereas the same injury would mar the 

 apple. 



Time of Application 



Based upon life-history studies of the 

 codling moth in the walnut conducted 

 last year, the first application should be 

 made during the last week of May and 

 the first week or two of June. The 



July, 1920 



second application should be made 

 about July 15. These dates are just 

 previous to the time when the maxi- 

 mum number of larvae of the two im- 

 portant broods enter the nuts. This ap- 

 plies to the Santa Ana district. At Car- 

 pinteria the time of appearance of the 

 broods is strikingly different from that 

 at Santa Ana. At Santa Ana the great- 

 est injury is done by the summer brood 

 in July and August, while at Carpin- 

 teria most injury is done by the spring 

 brood in the latter half of July. There 

 is, therefore, practically a full brood 

 less at Carpinteria, and on this account 

 one application ought to be sufficient. 

 The time for making this application 

 at Carpinteria would be the latter part 

 of June or the first part of July. 



Results of Dusting, 1919 



A very complete survey of the area 

 infested with the walnut codling moth 

 was made as the nuts were harvested 

 at Santa Ana, and also at Carpinteria. 

 More than 200,000 nuts, representing 

 some 5,000 pounds, were separately ex- 

 amined. Counts were made with each 

 pick in most cases, and a reliable figure 

 representing the percentage of infesta- 

 tion was secured from over 100 or- 

 chards, about one-half of which were 

 dusted and one-half were not dusted. 



TABLE I.— SURVEY OF SANTA ANA AREA. 

 Per cent 

 wormy 

 General average all orchards dusted.... 4.73 

 General average orchards not dusted. . . . 6.33 

 Highest pet. in single orchard dusted... 10 

 Highest pet. single orchard not dusted. .21.9 



Lowest pet. single orchard dusted 8 



Lowest pet. single orchard not dusted. . .33 



TABLE II.— SURVEY OF CARPINTERIA AREA 



General average orchards dusted 4.2 



General average orchards not dusted. . . 9.7 



Highest pet. single orchard dusted 6.6 



Highest pet. single orchard not dusted.. 15. 8 



Lowest pet. single orchard dusted 7 



Lowest pet. single orchard not dusted.. .8 



Referring to the figures given in 

 Tables I and II, it is assumed that most 

 of the heavily infested orchards were 

 dusted. That was the case at least at 

 Carpinteria. One orchard well toward 

 the center of the infested area in that 

 section, however, was left untreated 

 and another not treated until very late. 

 These two orchards, only, furnish the 

 figures "9.7," for "not dusted," under 

 Carpinteria. If counts were made just 

 outside the infested district at Carpin- 

 teria they would show practically no 

 infestation, whether dusted or not. 



At Santa Ana, however, many or- 

 chards were not dusted that were dis- 

 tributed among the dusted orchards and 

 were in general area of infestation. Ap- 

 proximately an equal number of de- 

 terminations was made also between 

 dusted and not dusted orchards, so that 

 the figures should be fairly reliable. 



Cement Coated Wire Nails 



If your dealer cannot or will not 

 supply you with Nails, we probably 

 can do so. 



A. C. RULOFSON CO. 

 Monadnock Building, San Francisco 



rlON BETTER FRl'IT 



