IQII 



BETTER FRUIT 



Page 77 



SOLVING THE PROBLEM OF THE CODLING MOTH 



BY E. P. TAYLOR, GRAND JUNCTION, COUNTY ENTOMOLOGIST AND HORTICULTURAL INSPECTOR OF MESA COUNTY, COLORADO 



ONE of the most common questions 

 heard, last summer and fall was: 

 "Why do we have so many wormy 

 apples? Is it the spray, or what is the 

 matter?'" 



Many have expressed their opinions as 

 to the cause, and I might repeat the con- 

 clusions I have formed, with an idea of 

 pointing out ways we may improve our 

 conditions another year. 



In the first place I do not think that the 

 quality of the arsenate of lead used this 

 season by our Grand Valley growers was 

 at fault in the main. As evidence of this 

 it may be cited that at least half a dozen 

 different brands of arsenate of lead were 

 used throughout the valley. and, with a 

 few exceptions, comparisons failed to 

 indicate that this was the source of the 

 trouble. I do not wish to convey the 

 idea that all arsenates of lead are the 

 same, and that it is not of greatest 

 importance each season for growers in 

 purchasing them to make sure of both 

 their total arsenic content and the 

 amount of free arsenic which will cause 

 burning. There were individual failures 

 in spraying in this valley last season, just 

 as there have been in other seasons, 

 from lack of thoroughness, disregard for 

 the timing of sprays in relation to the 

 life history of the moth, insufficient hand 

 and power spray outfits to cover the 

 orchards at the proper times and poor 

 kinds of spray pump accessories. I do 

 not think that these details were neg- 

 lected any more this year, proportion- 

 ately, than in the five years preceding, 

 for they have always been the bugaboos 

 of the ones who have been placed in the 

 position of advisers to fruit growers in 

 matters of codling moth spraying. 



Then why has the loss from codling 

 moth been greater this year than in 

 some j'ears before? The principal expla- 

 nation seems to lie in the superabun- 

 dance of worms this year, due to several 

 natural causes. A combination of these 

 natural conditions made codling moth 

 life very easy the past season, so easy 

 in fact that the moth proved a winner 

 in many cases against spraying methods 

 which had won the battle for growers in 

 previous j-ears. 



A high percentage of the hibernating 

 larvae came through the winter of 1909- 



10 alive, perhaps due, as some have sug- 

 gested, to a cold winter, with even 

 instead of varying temperatures. The 

 freezing and thawing conditions are more 

 destructive to hibernating larvae, it is 

 thought, than a prolonged and even win- 

 ter temperature, even though very cold. 



Adding still more to the odds of the 

 moth a comparative light crop of fruit 

 prevailed in many orchards, thus con- 

 centrating the attack, and, as a final 

 handicap for the worms, the season of 

 their breeding was hot and dry, almost 

 beyond precedent (a condition that is 

 most favorable for their multiplication). 

 The mean monthly temperatures for 

 Alay, June and July, 1810, exceeded these 

 months for the five preceding years. 



As a result of the natural conditions 

 favoring the moth, eggs were deposited 

 and worms hatched during the season in 

 numbers exceeding any record ever made 

 of this pest before. I have, for a num- 

 ber of years in codling moth work, made 

 sj-stematic observations in the orchards 

 for the eggs, and the enormous increase 

 in numbers of eggs encountered this 

 season was very apparent. Five years 

 ago, in this valley, when my observations 

 were kept up for over three months, 

 about 1,000 eggs were tabulated. This 

 j'ear had an attempt been made to record 

 the eggs seen I am afraid I would have 

 been yet engaged, with a goodly clerical 

 force, footing up the totals. Just as an 

 example of a few counts made this sea- 

 son the following may be given from my 

 notes of August 25 in an orchard which 

 had been sprayed. The eggs were found 

 with but a few moments' search either 

 upon the fruit itself or upon the leaves 

 or twigs about it. Many of the empty 

 shells had possibh' been washed or 

 blown away before counting, but the fol- 

 lowing still remained: Two Winesaps, 

 48 eggs and shells; one Jonathan, 52; one 

 Winesap, 14: one Jonathan, 61; tv.o Jon- 

 athans, 108; one Jonathan, 57. 



About the eight apples at least 340 

 codling moth eggs had been deposited, 

 or an average of 42 eggs per apple. 

 Under such conditions is it strange that 

 a few worms should have escaped even 

 the most thorough spraj'ers? One worm 

 biting through the skin out of the 42 

 eggs makes a specked apple and one 



into the flesh a wormy apple. As a 

 result of such an onslought of codling 

 moth, here is what happened in a few 

 unsprayed orchards. 



On June 18, in an unsprayed Ben 

 Davis orchard, 97.2% of the apples still 

 upon the trees were already wormy by 

 the first brood worms, with an average 

 of more than three worm holes per 

 apple. On the same day counts made in 

 an unsprayed Winesap orchard gave 

 96.6% wormy, and a third unsprayed 

 orchard on July 1 gave 96.8% wormy, 

 both including only the fruit still upon 

 the trees. In the last case the average 

 worm holes per apple was more than 

 three. These three instances cite the 

 damage done by first brood worms alone. 



In the season of 1906 the writer, under 

 the direction of Professor Gillette, con- 

 ducted very extensive spraying experi- 

 ments in four separate orchards of the 

 Grand Valley, detailed records being 

 tabulated at the end of the season involv- 



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