NURSERY AND ORCHARD INSECT PESTS 9 



are planted. However, it should be remembered that in recent years most 

 new infestations in orchards come from other infested orchards in the vicinity 

 rather than on the young trees from the nursery. 



While the scale has done much injury to fruit growing it is now possible to 

 control it very effectively and in good orchard management it is no longer 

 feared as a dangerous scourge. The above discussion of the pest on apple holds 

 true for other tree fruits as well. 



Other Scale Insects. The oyster shell scale, the scurfy scale and the 

 Forbes scale are also at times common on apple trees in the nursery and in the 

 orchard. Neither of these, however, are likely to cause serious injury to bear- 

 ing trees. In the nursery, on the other hand, they are undesirable and at times 

 decidedly injurious. The scurfy scale has a light-colored flaky, armor, the 

 oyster shell has a dark oyster-shell-shaped armor and the Forbes a circular 

 armor with a shiny orange-colored center or exuvae. 



CONTROL. In the propagation of nursery stock select scions free from 

 scales. Where nursery stock shows infestation do not use it in filling orders. 

 To most fruit growers a scale is a scale and a nurseryman does not want the 

 name of distributing scale infested stock. Dipping nursery stock in a miscible 

 oil or fumigating with hydrocyanic acid gas will prevent the possibility of 

 spread of these scales on the stock. In the orchard where these scales are 

 troublesome a dormant spray as for the San Jose scale is helpful, especially for 

 the Forbes scale and spring applications of contact sprays as for plant lice, just 

 when the young scales are crawling is very effective in controlling the scurfy 

 and oyster-shell scales, since they pass the winter in the egg stage. 



Buffalo Tree-hopper (Ceresa bubalus). In old neglected orchards the 

 bark of small limbs and twigs is often found to be badly pitted and roughened. 

 This is caused by this small insect. In the fall, by means of a small drill or 

 ovipositor, the female places her eggs under the bark and this causes small scars 

 on the bark. The injury is similar to the work of the Cicada, tho the punctures 

 do not go beyond the bark. These eggs hatch in the spring and the young 

 nymphs soon leave the twigs and feed on the sap of herbaceous plants, grass 

 and the like about the orchard. The only damage done is due to the egg lay- 

 ing and in severe cases it may be considerable. Certain varieties suffer more 

 than others. 



In the nursery this injury is usually slight, tho it may be quite noticeable 

 especially on scion trees in places where surrounding conditions are favorable 

 for breeding. 



CONTROL. Where this pest is abundant clean culture in the orchard and 

 surrounding fields will help to check the pest and its injury. Repeated mowing 

 of grass and weeds in the orchard will help where cultivation is not advisable. 



Periodical Cicada (Tibicen septendecim).This peculiar insect, as is well 

 known, reappears at definite intervals in the form of broods. One form re- 

 appears every thirteen years and the second every seventeen years. In Mis- 

 souri several broods appear, tho only the two heavy 13-year broods are of special 

 importance. One of these appeared in the spring of 1920 and will next appear 

 in the spring of 1933. The second appeared last in the spring of 1911 and will 

 next appear in the spring of 1924. These two broods are sufficiently heavy and 

 widely distributed as to cause a certain amount of damage to the fruit-bearing 

 twigs of apples and other fruits over most of the state. This is especially true 



