Page 12 



BETTER FRUIT 



February 



stimuli, showing itself cither in the 

 form of increasing or retarding emer- 

 gence, occurred. A much greater vari- 

 ation in the emergence of the moths has 

 been noted where transfers from the 

 tree trunks were made during the 

 spiiiii,' of the year. The mortality of 

 spring transfers is also much higher. 

 making it often iliflicult to gather ac- 

 curate information. To facilitate the 

 stocking of cages, trees are usually 

 banded before the worms leave the 

 fruit. Many of the insects establish 

 themselves in the folds of the burlap 

 which is used and transferred to the 

 (aye, without disturbing them if their 

 cocoon has already been spun. Others 

 can be readily removed from the trunk 

 and be placed in the cages which have 

 been provided with bark, chips and 

 decaying bits of wood in which the 

 larvae readily establish themselves. To 

 determine development from some of 

 the worms which have not suffered 

 transferring, worm-infested apples are 

 placed in the cages; these are removed 

 as soon as the worms have left the fruit. 



The cages are distributed throughout 

 the valley at different altitudes. Com- 

 mercial apple orchards are found at 

 heights ranging form 100 to nearly 2,000 

 feet. The average seasonal variations 

 in the two extremes given has been 

 found to be from fifteen days to three 

 weeks for the first brood and about ten 

 days for the second. In the emergence 

 of the first brood a very definite pro- 

 gression from the lower to the higher 

 elevations occurs; it is much less pro- 

 nounced for the second, due probably to 

 the fact that summer temperatures 

 during the day at least are more nearly 

 uniform throughout the valley than are 

 the spring temperatures. 



As near normal orchard conditions as 

 can be determined are taken into con- 

 sideration when establishing the cages. 

 This particularly refers to sun ex- 

 posures, wind and rain that emergence 

 may be as nearly uniform to the sur- 

 rounding orchard conditions as pos- 

 sible. As far as time has permitted 

 breeding-cage observations and notes 

 have been checked against field obser- 

 vations. 



In comparing the dates of emergence 

 of the moths of the first brood over this 

 series of years there occurred a varia- 

 tion of a full month and a half. A rec- 

 ord was not obtained in 1914, but in 

 1915 the first moths issued in the cages 

 on April 27. In 1910 this phenomenon 

 occurred on May 26 and in 1917 on 

 June 15. The question that immediately 

 presents itself is: What factor or group 

 of factors is responsible for that very 

 marked variation. A study of the exist- 

 ing weather conditions during these 

 years assist to a large degree in supply- 

 ing the answer. 



Owing to the fact that the writer did 

 not arrive in Hood River until the 

 middle of July, 1914, observations were 

 not taken relative to the weather con- 

 ditions during the early season. How- 

 ever, a study of the daily weather re- 

 port indicates that the temperatures for 

 April, May and June for this year were 

 exceedingly mild. The mean average 

 temperature being much higher than in 

 any of the other three years under con- 



sideration, and is largely due to the fact 

 thai the average minimum temperatures 

 were uniformly higher during the three 

 months. The result was that codling 

 moths issued in large numbers early in 

 the season. This was followed by fa- 

 vorable weather conditions for egg 

 deposition and hatching. Mr. G. F. 

 Moznette, who made observations at 

 Hood River on the activities of the cod- 

 ling moth during the spring of 1914, 

 found eggs hatching in large numbers 

 in several orchards on June 5. On this 

 dale many of the worms had entered 

 the fruit. Summer weather during July 

 and August continued favorable for de- 

 velopment. The first worms were found 

 leaving the apples on June 24; pupae 

 were noted on July 7 and moths 

 emerged July 19. On July 27 the first 

 eggs of the second brood were found on 

 the fruit. The station gave out at this 

 time notices for growers to begin their 

 spraying operations for the control of 

 the second generation of worms. 



In 1915, during the months of April, 

 May and June, there was much more 

 fluctuation in the daily temperatures 

 than in the corresponding time during 

 1914. The average maximum tempera- 

 ture for 1915 was practically the same 

 as for 1914, but the minimum tempera- 

 tures were very much lower. In 1915, 

 due to this fluctuating daily tempera- 

 ture, breeding-cage observations seemed 

 of little importance when correlated 

 with liming of sprays for the control 

 of the first generation of worms. The 

 latter part of April and the first few 

 days of May were very warm, resulting 

 in the emergence of numerous moths in 

 the breeding cages on April 27 and the 

 days immediately following. At the 

 time the calyx spray was being applied 

 in an orchard in which the writer was 

 carrying on experimental work many 

 moths were flushed from the trees when 

 the spray was thrown into the foliage. 

 Following the 0th of May and continu- 

 ing throughout the remainder of the 

 month rainy, cold weather occurred. 

 The influence of these conditions not 

 only prevented emerged moths from 

 depositing eggs, but checked — practi- 

 cally stopped — emergence which had 

 begun on April 27. Eggs of the codling 

 moth were not found until May 28, one 

 month after the emergence of the first 

 insects. These were found plentifully 

 during the month of June and early in 

 July. The first hatching eggs were 

 noted on May 31. The average maxi- 

 mum temperature during July was 

 about six degrees below normal, which 

 apparently retarded the development of 

 the insects during this time. The first 

 moths of the second generation issued 

 July 26 and eggs were first noted August 

 10, fourteen days after the egg hatching 

 of 1914. Growers were advised to have 

 their spray on by the 12th, or fifteen 

 days later than was recommended the 

 preceding year. 



The year 1916 proved to be one of 

 more irregularities in the habits of the 

 codling moth than of any ever previ- 

 ously studied by the writer. Spring and 

 summer seasons were very far from 

 normal. The spring and early summer 

 was cold and accompanied by many 

 rainy days, and late summer, though 



fair weather prevailed, at no time did 

 it become warm. The first moths issued 

 in the breeding cages May 26, or at 

 practically the same lime eggs were 

 present on the trees during the two 

 preceding seasons. Emergence of moths 

 was at its height between the 6th and 

 15th of June. On June 10 the first eggs 

 of the season were observed. Begin- 

 ning with the 17th of June (at which 

 time egg deposition should have been 

 at its height) rainy-weather conditions 

 set in, which continued until July 4. 

 During this time temperatures were 

 very low, there being only five days 

 during this period at which time the 

 thermometer registered above 60 de- 

 grees at sunset (the theoretical mini- 

 mum temperature required by the cod- 

 ling moth for the deposition of eggs). 

 Of these five days, three registered 62 

 degrees. Eggs of the first generation 

 were found present on the fruit as late 

 as the 8th of August, but at no time dur- 

 ing the summer were they numerous. 



Moths of the second generation were 

 found for the first time on August 18, 

 exactly one month later than in 1914 

 and twenty-two days later than in 1915. 

 But very few second-brood moths ap- 

 peared in 1916; for the most part but 

 one generation occurred. This definite 

 statement can be made due to results 

 of breeding experiments conducted to 

 determine this point. Those worms 

 which resulted from eggs deposited 

 prior to the cold, rainy weather which 

 extended from June 16 to July 4 pro- 

 duced second-generation insects; those 

 insects resulting from eggs deposited 

 following this cold period failed to un- 

 dergo any changes after they left the 

 fruit and remained as larvae on the 

 trees until the spring of 1917. 



The year 1917 was productive of still 

 different irregularities in codling-moth 

 behavior. The past season has been 

 one accompanied by heavy losses in 

 many Xorthwestern apple-growing sec- 

 tions due to the great numbers of 

 worms. Hood River was apparently 

 more fortunate than most of the sec- 

 tions in this respect, but nevertheless 

 losses resulting in a good many or- 

 chards were serious. 



In 1917 the early season was very 

 backward; March, April and May were 

 quite cold, accompanied by many days 

 of rain. This prevailing condition had 

 a very marked influence on plant de- 

 velopment; leaf buds on the apple trees 

 did not begin to burst till the first of 

 May. At this time during the years 

 1914 and 1915 the petals were falling, 

 followed shortly by the calyx spray. 

 Even after this late date foliage devel- 

 opment continued to be very slow ow^ 

 ing to the continued low temperatures. 

 The average maximum temperature for 

 the month of May was but 62 degrees. 

 A temperature of 70 degrees was not 

 reached until the last day of the month. 

 With the arrival of June weather condi- 

 tions changed; continued warm, settled 

 weather following June 4. The first 

 moth, however, did not emerge in the 

 cages until June 15. This observation 

 was checked up with orchard condi- 

 tions during this period and no moths 

 found to have issued under field condi- 

 tions up to this time. This date was 



