Wild plums of several species seem to be favorite feeding grounds for the tent caterpillar[193] (Malacosoma americana Fabricius), but cultivated plums are not so often attacked; the spraying with arsenites usually given for the curculio is fatal to this pest as well. The spring canker-worm[194] (Paleacrita vernata Peck) and the fall canker-worm[195] (Alsophila pometaria Harris) are other caterpillars which often do much damage unless checked by destructive measures, of which the best are the arsenical sprays. The larvæ of a considerable number of other moths and butterflies are often found on plum foliage but seldom in such numbers as to require systematic destruction.
The eye-spotted bud-moth[196] (Tmetocera ocellana Schiffermuller) is a rather serious pest in plum nurseries where the larvæ eat into the young buds at the time they are opening, often destroying the shoots. Sometimes the larvæ are found destroying buds on old trees. The arsenical sprays are used to destroy this pest. The peach twig-moth (Anarsia lineatella Zeller) is now and then found in plum twigs but is seldom classed as a plum pest.
The clover mite[197] (Bryobia pratensis Garman) formerly considered a serious pest of the plum only in the far West, is now abundant in plum orchards in New York. It can be controlled by applications of lime and sulphur. The bumble-flower beetle[198] (Euphoria inda Linnaeus) is reported by Goff to be occasionally very injurious to plums in Wisconsin. Remedies seem not to have been tried. The larvæ of the cherry slug[199] (Selandria cerasi Peck) is not infrequently found doing damage to plum foliage and occasionally the larvæ of one or two other saw-flies feed on the plum. These are all overcome by the use of arsenical sprays. At least one of the curious insects know as “case-bearers” attacks the plums. The troublesome one is the pistol case-bearer[200] (Coleophora malivorella Riley), which is not often a pest but has sometimes done considerable damage. Attempts to check this insect with the arsenical sprays have usually proved successful. The plum tree is a host-plant of the hop aphis[201] (Phorodon humuli Schrank). So much does this insect feed on the plum that the destruction of plum trees in the vicinity of hop fields is recommended to hop-growers by Riley.
CHAPTER III
LEADING VARIETIES OF PLUMS.
ABUNDANCE
ABUNDANCE
Prunus triflora
1. Am. Pom. Soc. Rpt. 96. 1887. 2. Am. Gard. 9:360. 1888. 3. Ga. Hort. Soc. Rpt. 51, 52, 53, 99. 1889. 4. Bailey Ann. Hort. 103. 1889. 5. Am. Pom. Soc. Rpt. 106, 125. 1891. 6. Am. Gard. 13:700. 1892. 7. Rural N. Y. 52:666. 1893. 8. Cornell Sta. Bul. 62:19, 27, 32. 1894. 9. Tex. Sta. Bul. 32:488. 1894. 10. Rev. Hort. 160. 1895. 11. Mich. Sta. Bul. 118:52. 1895. 12. Cornell Sta. Bul. 106:41, 43, 44, 47, 48, 49. 1896. 13. Va. Sta. Bul. 67:96. 1896. 14. Cornell Sta. Bul. 131:195. 1897. 15. Ibid. 139:37, 38, 39, 40. 1897. 16. Am. Pom. Soc. Cat. 26. 1897. 17. Cornell Sta. Bul. 175:141, 142, 143. 1899. 18. Waugh Plum Cult. 132, 135. 1901. 19. Mich. Sta. Bul. 169:242, 248. 1899. 20. Ont. Fruit Exp. Sta. Rpt. 15. 1902. 21. Ohio Sta. Bul. 162:254, 255. 1905. 22. Texas Nur. Co. Cat. 9. 1907. 23. Ga. Sta. Bul. 68:7, 28. 1905.