April. 1920 



BETTER FRUIT 



Page 7 



Dusting and the Spray Gun in Calyx Worm Control 



EVER since the late Dr. A. J. Cook 

 carried on some calyx worm con- 

 trol experiments in Michigan a 

 half century ago entomologists have 

 argued relative to the way and in the 

 amounts this poison becomes estab- 

 lished in the calyx cups. The correct 

 type of nozzle and the kind of spray 

 necessary to accomplish best results 

 have been a much mooted question. In 

 this connection some of our more en- 

 thusiastic colleagues have even gone so 

 far as to believe that one well-timed 

 calyx application would be sufTicient to 

 handle the codling moth under ordinary 

 seasons of infestation. 



Observations made by investigators in 

 different parts of the country during 

 recent years have pointed out that the 

 percentage of calyx entrants is a very 

 variable factor during different sea- 

 sons in different .sections. It has been 

 the writer's observation that during 

 some seasons a very high percentage of 

 the worms enter through the calyx and 

 during others the reverse would be true. 

 During the past season the worms en- 

 tered in about equal proportions 

 through the calyx and side on Spitzen- 

 bergs, while in Newtowns, side en- 

 trants occurred in a much larger pro- 

 portion. From information that I have 

 received from various sources a condi- 

 tion of this sort was quite general 

 throughout the Northwest during the 

 past year. 



It is not ray purpose to in any way 

 depreciate the importance of the calyx 

 application in the minds of orchardists. 

 The more stress that we can lay upon 

 this and the cover sprays the better 

 will be the results. However, over- 

 emphasis of the calyx application has 

 been harmful in that it has had a tend- 

 ency to depreciate (in the minds of the 

 growers) the value of cover sprays and 

 much worminess has been the result. 



The writer has been keeping in very 

 close touch with codling moth activities 

 in Hood River for six years. During 

 the past four years experimental work 

 with dust and sprays of various sorts 

 have been under observation. 



The dusting method of applying ar- 

 senate of lead and sulphur to apples for 

 the control of various insects and plant 

 diseases created much interest follow- 

 ing the publication of the work of Red- 

 dick and Crosby (Bulletins 334 and 369, 

 Agricultural Experiment Station, Cor- 

 nell University) in 1914 and 1915. The 

 results of their work indicated that 

 apple insects and diseases of import- 

 ance in the East, other than San Jose 

 scale and the various apple aphids 

 could be controlled in about the same 

 degree as with the liquid. In the West 

 we have to add to this list of uncon- 

 trollable troubles, powdery mildew, 

 anthracnose, and the leaf roUcr as well 

 as a few minor insect pests. This fact 

 places very decided limit upon the 

 general utility of the method and makes 

 it a means of general control that we 

 cannot recommend. 



The results of Reddick and Crosby 



By Leroy Childs, Entomologist and Pathologist, Hood River Experiment Station 



are especially interesting to me as I complish results. Several of nur grow- 



have been able to duplicate their re- ers have used the dusting method; for 



suits with scab and codling moth con- the most part their work has been done 



trol during the four years of the inves- regardless of air movement. In 1918 

 To the entomologist working 



tigation. 



on codling moth control, these results 

 should be decidedly significant. Red- 

 dick and Crosby do not go into the 

 critical analysis of the proportions of 

 calyx and side worms yet their good 

 results indicate that they accomplished 

 calyx worm control. How can the ad- 

 vocate of the so-called driving calyx 

 spray explain this control? The writ- 

 er's work shiws that this control is 

 very decidedly accomplished. The dust 

 cannot be driven. Quiet air-atmosphere 

 is the carrying medium used in placing 

 the dust particles on the surfaces which 

 require protection. A wonderful coat- 

 ing can be given a tree even to its up- 

 permost branches. Upper and under- 

 surfaces of the leaves as well as the 

 fruit alike are covered. This air con- 

 veyor being in motion a slight breeze, 

 very light, upsets the plans of proced- 

 ure! A breeze makes it almost impos- 

 sible to hit the tops and even if this 



the condition of the fruit in one of 

 these orchards was checked up; a 33 

 per cent injury from the codling moth 

 was found. None of the growers of the 

 valley have depended upon the system 

 during the past year. On account of 

 the many handicaps and difficulties en- 

 countered I do not recommend the 

 method to our growers except those lo- 

 cated on steep hillsides and in sections 

 where sufTicient water for spraying is 

 difficult to obtain. 



The results, however, that have been 

 obtained in calyx worm control have a 

 very decided bearing on the results that 

 can be expected with the spray gun 

 when properly used. For this reason I 

 will discuss some of the results that 

 have been obtained in seasons past with 

 both dust and liquid applications. These 

 results are summarized on the accom- 

 panying chart. In 1917 the unsprayed 

 check trees in an orchard which had 

 been quite wormy for several seasons, 



Apple blossoms just after the 



falling of petals; best time to 



spray for codling moth. 



were accomplished the particles are 

 moved past the surfaces so fast that 

 only a very small percentage sticks. 

 The remainder passes on and is wasted 

 for the most part. When the air is 

 quiet these particles will hover for a 

 long time over a tree and gradually 

 settle. Air currents destroy the plan of 

 the system and applications made under 

 such conditions can only result in dis- 

 aster. 



In order to avoid windy conditions it 

 was found necessary to dust very early 

 in the mornings; a calm usually occurs 

 in most sections of the valley during 

 this period of the day. However, with 

 us during the spring months it is not 

 uncommon for a wind of varying de- 

 gree to occur continuously for several 

 days at a time. Many times in the carry- 

 ing out of the experimental work the 

 dusting had to be postponed for more 

 favorable weather. We are all familiar 

 with the fact that .successful applica- 

 tions of spray cannot be delayed to any 

 great extent and at the same time ac- 



Almost too late for the most efTective 



treatment. Observe that the calyx cup 



is nearly closed. 



developed an infestation of 65.13 per 

 cent. Of this infestation 31.68 per cent 

 were side worms and 68.32 per cent 

 were calyx worms. The variety used 

 in this set of experiments were Arkan- 

 sas Blacks. This ratio did not hold true 

 in all varieties. In an orchard of 

 Spitzenbergs this ratio was 66.96 per 

 cent side worms and 33.04 per cent 

 calyx worms. In a Newtown block 

 this ratio was 61.54 per cent to 38.46 

 per cent side and calyx worms respect- 

 ively. In the block of Arkansas Blacks 

 two dust experiments were checked 

 against two blocks of trees sprayed 

 with twelve foot rods. In experiments 

 number 1 and 3 an early September ap- 

 plication was omitted, resulting in a 

 much more wormy condition than oc- 

 curred in experiments 2 and 4. These 

 different experiments are cited to show, 

 that regardless of this marked differ- 

 ence in worminess the general relation 

 of side and cahx worms remains fairly 

 constant, though with the increase in 

 total worminess the chances of calyx 



