Page 8 



BETTER FRUIT 



Febniarv 



usually migrates from the young wood 

 growth down the trunk to the roots of 

 the tree, and this migration may extend 

 over a period of two or more months, 

 being most noticeable with the advent 

 of the first cold nights in the early fall. 

 All the individuals of this generation 

 do not go to the roots, but some remain 

 above ground and produce a generation 

 of winged forms known as the sixth 

 generation or fall migrant, which may 

 be found about the trees in late fall 

 but generally migrates to elm trees, 

 where they settle upon the bark and 

 produce true sexual forms, the females 

 of which deposit a single egg each in 

 the crevice of the bark, where the egg 

 passes the winter. 



It should be understood from the out- 

 set that means of controlling this insect 

 must either be very thorough, which 

 would also be expensive if the work is 

 successfully done in a short time, or 

 else that control measures must be 

 practiced for a considerable length of 

 time, which, with this special insect, 

 usually involves careful work for at 

 least three full consecutive seasons. 

 Obviously, the more of the fall migrant 

 that can be killed before they go to the 

 ground or migrate to other places the 

 better. Following this, the next prac- 

 tical means is to kill, by the use of con- 

 tact insecticides, during June, July and 

 August, as many as possible of those 

 insects which can be found on the trees 

 (luring that time. Specific direction in 

 this regard will be given in the latter 

 part of this paper after brief mention 

 of the other two species of aphids 

 under consideration. 



The green apple aphis, usually known 

 as the leaf-curling aphis, is in many 

 orchards, especially on young trees, the 

 most noticeable species of the three 

 under consideration. Eggs are de- 

 posited in the fall of the year usually 

 on the young wood growth and water- 

 sprouts, sometimes in great numbers. 

 These eggs pass the winter as such, 

 hatching in the spring of the year 

 about the time wood growth starts. All 

 eggs are generally hatched by the time 

 the buds are open. From those forms 

 hatching from the over-wintering eggs 

 is started the production of an enor- 

 mous number of individuals, which 

 goes on for generation after generation 

 for two months, or sometimes longer if 

 the weather remains comparatively 

 cool. Roughly speaking, about twenty- 

 five days are required for the develop- 

 ment of a single individual. The green 

 apple aphis does some injury to the 

 fruit by puncturing the skin, but its 

 chief injury is caused from feeding on 

 the foliage, resulting in curling, dwarf- 

 ing and often killing the leaves to such 

 an extent as to prevent further wood 

 growth on the twigs attacked. 



The rosy apple aphis is primarily a 

 pest of the fruit. Injury from this 

 species results in producing the so- 

 called cluster apples, which are knotty, 

 misshapen and of little or no commer- 

 cial value. This is caused by the feed- 

 ing of this species while the fruit is 

 small. This species also feeds to some 

 extent on the foliage and is undoubt- 

 edly quite a factor in aiding the spread 

 of pear blight. This is also equally 



true with the green apple aphis pre- 

 viously mentioned. The eggs of the 

 rosy apple aphis generally hatch a 

 little later in the season than those of 

 the green apple aphis. This species is 

 particularly noticeable on the leaves 

 around the fruit clusters and on the 

 stems of the fruit. This species usually 

 disappears from the trees by mid- 

 summer, but appears again in small 

 numbers in the late fall where eggs are 

 deposited on the trunk and older 

 growth, but are not generally as plen- 

 tiful as eggs of the green apple aphis. 



The control of these species will 

 now be considered collectively in con- 

 junction with other spraying work nec- 

 essary in commercially profitable apple 

 orchards. During the dormant or win- 

 ter season, many of the eggs of the 

 green apple aphis can be killed by 

 spraying the trees with lime and sul- 

 phur solution or with a good con- 

 centrated oil spray at the same time 

 the work is done for scale control. In 

 the use of these sprays, however, it is 

 essential for success that the spray be 

 applied in fair weather, and if rain fol- 

 lows within three or four days after 

 spraying the application should be re- 

 peated. 'WTien the cluster buds begin 

 opening in the spring it is time to do 

 any spraying that is to be applied, if 

 success is expected, for controlling the 

 rosy apple aphis. The greatest part of 

 the injury done to the fruit by this 

 species is caused before the petals fall 

 from the trees. For this work, after 

 the cluster buds open but before bloom- 

 ing, distilliale oil emulsion, 3% con- 

 centration, can be effectively and safely 

 used, or a combination of whale-oil 

 soap and nicotine such as Black- 

 Leaf "40" may be applied. All apple 

 orchards infested with mildew should 

 be sprayed with atomic sulphur at the 

 same time. The atomic sulphur may be 

 safely and effectively combined at the 

 rate of 12 pounds for each 200 gallons 

 of spray with the distillate oil emul- 

 sion or with the nicotine used at this 

 time for aphis control. 



As soon as JLhe petals fall from the 

 trees, it is time to spray with arsenate 

 of lead for codling-moth control. 

 Dilute the distillate oil emulsion at the 

 rate of 5 gallons for each 200-gallon 

 tank of spray, adding the four pounds 

 of arsenate of lead paste or two pounds 

 of arsenate of lead powder for codling- 

 moth control. If mildew is present or 

 likely to cause injury, add 12 pounds 

 of atomic sulphur for each 200-gallon 

 tank of the diluted emulsion and arse- 

 nate of lead. These three materials 

 can be safely and effectively mixed 

 togetlier in the same spray tank. The 

 distillate oil emulsion used at this time 

 should effectively kill any and all green 

 aphis or rosy apple aphis which may 

 not have been killed by the application 

 before blooming. By the time of the 

 second application of arsenate of lead 

 for codling-moth control, about three 

 weeks after the petals fall, it is likely 

 that many specimens of the woolly 

 apple aphis will be present on the trees. 

 Also at this lime it is (lueslionalile if 

 the distillate oil emulsion can l)e safely 

 used as strong as recommended for the 

 earlier applications. Therefore at this 



three-weeks' spray use three gallons 

 of concentrated distillate oil emulsion 

 for each 200-gallon tank of spray, and 

 after this has been diluted in water 

 add the arsenate of lead, and, if mildew 

 is present, the atomic sulphur and one 

 pint of Black-Leaf "40" for each 200 

 gallons of spray. If these directions 

 are followed up to this time, all of the 

 green aphis and rosy apple aphis pres- 

 ent should have been killed and mil- 

 dew under effective control. 



At the time of the third application 

 for codling-moth control, the woolly 

 aphis will very likely be most abundant 

 and it is important that the spraying 

 be most carefully and thoroughly 

 applied. Use the distillate oil emul- 

 sion, Black-Leaf "40" and arsenate of 

 lead as directed at the time of the sec- 

 ond application for codling-moth con- 

 trol. If at this time the woolly aphis 

 is present in large colonies or clusters 

 on the limbs and scarred places of the 

 bark, it will be necessary to hold the 

 nozzles close to the clusters of aphis 

 and apply the spray with sufTicient 

 pressure to break up and practically 

 wash off these colonies. Those grow- 

 ers who make a fourth application of 

 arsenate of lead for codling-moth con- 

 trol should by all means use the dis- 

 tillate oil emulsion and Black-Leaf 

 "40" in conjunction with the arsenate 

 of lead if the woolly aphis is present 

 in the orchard. Fruitgrowers must not 

 expect to eliminate woolly aphis by 

 one or two applications in one season. 

 This summer work of combining dis- 

 tillate oil emulsion with arsenate of 

 lead should be practiced for at least 

 three consecutive seasons. In those 

 orchards where the fruit is picked 

 early in the fall a great deal of good 

 can be sometimes accomplished by 

 spraying the trees with a winter spray 

 of oil just as soon as the fruit has been 

 harvested. This would kill any scale 

 insects that might be present and will 

 also, if properly applied, kill all woolly 

 aphis present on the trunks and limbs 

 of the trees before they have migrated 

 to the ground or other trees. 



In conclusion 1 may say that con- 

 siderable benefit will result from a 

 careful control of these aphids aside 

 from eliminating the injury done 

 directly to the tree, foliage and fruit. 

 The aphis family is undoubtedly Ihe 

 greatest factor in disseminating and 

 scattering fireblight. It is unnecessary 

 to warn you of the injury and loss 

 caused by this disease, but please bear 

 in mind that the spraying schedule pre- 

 viously outlined, if carefully and thor- 

 oughly practiced each year, will very 

 materially lessen the spread of blight 

 and greatly reduce the amount of 

 blight cutting now necessary in many 

 orchards because there will be fewer 

 blight infections. 



The Oregon State Horticultural Soci- 

 ety, the oldest horticultural society in 

 the Northwest, held its thirty-first 

 annual meeting in Hood River, Decem- 

 ber 11-13. The meeting was well 

 attended. The addresses and dis- 

 cussions were extremely interesting, 

 instructive and valuable. 



