Pollination of Japanese Plums

New Zealand Journal of Agriculture, Volume 87, Issue 1, 15 July 1953, Page 20

Pollination of Japanese Plums

By

A. T. J. WATTS,

Stone Fruit Specialist, Department of Agriculture, Christchurch

SOME varieties of Japanese plum are self-fertile, that is, they will set a crop without being pollinated by another variety, but many are only partially self-fertile, and when bef^e"i. , ’„v’f d s " O s , .t Set V ’“'l “T 0,h "5 se ) f - !t ' r!le a " must be ■ oross-pollmated before any fruit ,s set. Very few home gardeners have room for more than one or two trees ot any kind ot stone truit, so that more thought must be given to the choice of varieties, or combinations of varieties, to ensure satisfactory crops than would be necessary in a large mixed planting.

AS far as is known, any of the standard varieties of Japanese plums grown in New Zealand will pollinate any other variety successfully, provided their flowering periods overlap sufficiently; there are no incompatible groups, though some varieties are better pollinators than others. However, in addition to blossoming dates several other factors must be taken into consideration to ensure regular cropping. Very often bees are present in only small numbers early in the season, and lack of competition may allow individual bees to concentrate on a small area, perhaps only one tree, so that there is no crosspollination, especially if trees are far apart. Sometimes, too, flowers of other plants (including weeds and cover crops) may be more attractive sources of pollen or nectar, so that fruit blossom is neglected. Nutrition of the tree is important; if insufficient food, especially nitrogen, is not available to the tree at blossoming time, the set is likely to be poor. If a single tree consistently bears little or no fruit and lack of a pollinator is thought to be the cause, there are several methods of overcoming this. The most satisfactory way is to plant a tree of a known pollinator close to the existing tree; if this is impracticable, several small branches in the top of the tree may be worked

over to a pollinating variety by grafting. As a temporary expedient, when the tree is in blossom, small flowering branches of a pollinator may be placed in tins or jars of water and hung up in the tree or placed close to it; these bouquets should be fairly high, as blossom on the ground or in the lower parts of the tree is less likely to be visited by . bees. . The table at right lists the pollinators believed to be effective for most of the commonly growing Japanese plums. Many of these are of local or Australian origin, and little work has yet been done on their compatibilities or pollination r e q u i rements; most of the

information is therefore based on observations of growers and Instructors of the Horticulture Division. Another point that restricts their value is that time of blossoming is influenced by many factors, including soil, climate, rootstocks, and cultural methods. The degree of overlap in the flowering dates of any two varieties will also vary from district to district and even from season to season in the one district. The list should therefore be regarded as making suggestions only, not as embodying recommendations applicable under all conditions.

SF Believed to be self-fertile. Sf Believed to be partially self-fertile. SS Believed to be self-sterile.

oo dciwvcu lu uv oun-aiuinc. * Any ; cultural treatment which reduces the vigour of Purple King appears to assist setting.

No. Variety Fertility Suggested pollinators 1. Alpha . . SS 2, 4, 17, 19, 29, 31 2 Billington .. SS 1, 7, 12, 14, 19, 24, 27, 28, 29, 31 3. Booth’s .. 12, 19 4. Burbank .’.' SF 1, 7, 8, 11, 16, 23, 24, 26 ' 5. Doris .. .. 7, 16, 17, 19, 23, 27 6. Duff’s Early Jewel .’.’ SF • 7. Early . Sultan 2, 4, 5, 12, 17 8. Elephant Heart (Masterpiece) .. .. SS 4, 12, 23 9. Epoch 12 10. Eord’s Early .. 17 11. Formosa :; Sf 4, 16, 19, 26 12. George Wilson (Omega) SF 1, 3, 7, 8, 9, 14, 18, 23, 25 13. Hermosillo 31 14. Mariposa :; SS 2, 12, 23 15. Narrabeen 19, 22 16. October Purple 4, 5, 11, 17, 26 17. *Purple King 1, 5, 10, 16, 21, 24, 30, 31 18. Improved Purple King 12, 27 19. Santa Rosa .. SF 1, 2, 3, 5, 11, 15, 20, 22, 24 20. Satsuma . . SF 19 21. Sharp’s Early .. . . SF 17, 31 22. Shiro 15, 19, 26 23. Sultan " Sf 4, 5, 8, 12, 14 24. Vaile’s Early .. 2, 4, 17, 19 25. Victory .. 12 26. Wickson " SS 4, 11, 16, 22 27. Wilson’s Early .. .. SF 2, 5, 18 28. Wright’s Delicious .. SF 2 29. Wright’s Early .. .. SF 1, 2 Other Species 30. Evan’s Early (European) 31. South Australian Cherry Plum (Myrobalan)