- 8 - 



The authors concluded 

 on firmness and shelf-life 

 of yields and fruit size, 

 indicated that the highest 

 from the medium K (0.66 lb 

 proper balance of K and Mg 



high yields but also for good quality 



that the unfavorable influence of Mg 

 must be considered against the increase 

 Yield data (presented in another paper) 

 ields over a number of years resulted 

 high Mg (0.24 lb.) treatment. A 

 apparently is essential not only for 



yie' 



*************** 



GREEN APPLE APHID - ITS LIFE HISTORY AND CONTROL 



Gary L. Jensen 

 Department of Entomology 



Green apple aphids are found more often than any other aphid 

 on apple foliage. Apple cultivars most seriously infested are 

 Baldwin, Red and Golden Delicious, Cortland, Gravenstein, and Green- 

 ing, but Mcintosh also often serves as an important host of migrat- 

 ing aphids. Additional hosts of the apple aphid include pear, haw- 

 thorn, crabapple, quince, and possibly other members of the rose 

 fami ly . 



Green apple aphids may infest terminals and water sprouts of 

 fruit trees throughout the growing season. Since winged migratory 

 forms of this insect appear in every generation, rei nf estation and 

 buildup to damaging numbers can occur yery rapidly under favorable 

 conditions. Relatively cool weather with an abundance of rainfall, 

 such as occurred in the summer of 1970, favors succulent tree growth 

 and thus provides favorable conditions for heavy infestation of 

 green apple aphids. 



Injuries to apple trees by these aphids may appear as follows. 

 (l)Terminal leaves are stunted and distorted, and terminal growth 

 may be crooked and shortened. (2)Fruit and leaves may become black 

 and smutted due to the growth of sooty mold on the honeydew secre- 

 ted by the aphids. (3)With severe infestations, aphids may feed on 

 the fruit causing gnarling and dimpling of the fruit. 



Several natural enemies of aphids, including small parasitic 

 wasps, the larvae of syrphid flies and lace wing flies, and both 

 larvae and adults of lady beetles prey upon them and thus can gov- 

 ern buildup of aphids. However, most modern-day insecticides used 

 in apple orchards severely restrict these natural predators and 

 therefore make chemical control of measures necessary. These meas- 

 ures may be a part of the regular summer schedule, but regardless 

 of the spray program followed earlier in the season, growers need 

 to watch for aphid buildup in early- and mid-summer. An understand- 

 ing of the life-cycle and possible control measures should help in 

 combatting the green apple aphid. 



